US Anny Corps 

of Engineers 

Institute for 

Water Resources 

NATIONAL ECONOMIC DEVELOPMENT 

PROCEDURES MANUAL 

COASTAL STORM DAMAGE AND EROSION 

SEPTEMBER 1991 IWR Report 91-R ... 6 
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4. TITLE AND SUBTITLE 5. FUNDING NUMBERS 

National Economic Development Procedures Ma;lUal Coc:stal 

Storm Damage and Erosion 

6. AUTHOR(S) 

L. Leigh Skaggs and Frank L. McDonald, Editors 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION 

USACE, Water Resources Support Center REPORT NUMBER 

Institute for Water Resources 91-R-6 7701 Telegraph Road, Casey Building IWR Report 

Ft. Belvoi.r, VA 22060-5586 

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U.S. Army Corps of 

AGENCY REPORT NUMBER 

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13. ABSTRACT (Maximum 200 words) 

The purpose of this manual is to provide a description of coastal storm damage 

erosion prevention benefit evaluation procedures based on principles included. The 

U.S. Water Resources Council's Economic and Environmental PrinciEles and Guidelines 

for Water and Related Land Resources ImElementation Studies. The report presents 

selected, specific procedures for the entire process of benefit estimation and is 

intended for use in project feasibility planning and evalution. It is intended to 

serve as a reference guide to questions posed by an economic analyst in conducting 

a coastal storm damage and erosion prevention benefit evaluation. 

14. SUBJECT TERMS 

Coastal Storm Damage, Long-Term Erosion, Lost Benefit Analysis, 

National Economic Development Benefits 

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 

DF REPORT OF THIS PAGE OF ABSTRACT 

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20. LIMITATION OF ABSTRACT 

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Standard Form 298 (Rev 2-89) P'E"~(nbed by ANS,I S,td l39·18 lY8·10Z 
SEPTEMBER 1991 

NATIONAL ECONOMIC DEVELOPMENT PROCEDURES MANUAL 

COASTAL STORM DAMAGE AND EROSION 

Edited by 

L. LEIGH SKAGGS 

FRANK L. McDONALD 

U.S. ARMY CORPS OF ENGINEERS 

WATER RESOURCES SUPPORT CENTER 

INSTITUTE FOR WATER RESOURCES 

FORT BELVOIR, VIRGINIA 22060-5586 

IWR REPORT 91-R-6 

PREFACE 

This manual is part of a series of comprehensive guides designed to 

assist in the calculation of National Economic Development Benefits. It was 

sponsored by Headquarters, U.S. Army Corps of Engineers (HQUSACE), as part of 

the Planning Methodologies Research Program. Mr. Robert Daniel, Chief of the 

Economic and Social Analysis Branch (CECW-PD), Mr. William Hunt, Economist 

(CECW-PD), and Mr. John Housley, Senior Coastal Engineer (CECW-PF) served as 

Technical Monitors. Mr. William J. Hansen of the Institute for Water 

Resources (CEWRC-IWR-R) was the study manager. Mr. L. Leigh Skaggs, also of 

the Institute for Water Resources (CEWRC-IWR-R), and Mr. Frank L. McDonald 

(CENPD-PL-EC) served as primary editors. 

The manual is the product of work and review by many individuals. A 

first draft was prepared by a team of authors from the North Pacific Division 

(CENPD), including Mr. Frank McDonald, Mr. Ken Boire (CENPD-PL-EC), Mr. Steve 

Chesser (CENPP-PL-CH), Ms. Mona King (CENPP-PL-EE), Mr. Brent Mahan 

(CENPA-EN-PL), Mr. Ken Eisses (CENPA-EN-HH), Mr. Tom White (CENPD-PL-EC), and 

Mr. Ed Woodruff (CENPD-PL-EC). That draft was based on an annotated outline 

developed by a group of Corps planners, economists, and coastal engineers at 

an Issues Identification Workshop hosted by Jacksonville District (CESAJ) in 

February 1989. Workshop participants included Mr. Ken Claseman (CECW-PD), Mr. 

John Housley (CECW-PF), Mr. Phil Thorpe (CENAP-PL-PE), Mr. David Timpy (CENAPPL-PP), Mr. Chris Glanz (CENCD-PL), Mr. Charles Joyce (CENED-PL), Mr. Ed 

iii 
O'Leary (CENED-PL-I), Mr. Ken.Boire (CENPD-PL-EC), Mr. Harry Shoudy (CESAD-PDE), Mr. Gerald Melton (CESAC-EN-PE), Mr. David Schmidt (CESAJ-PL), Mr. Frank 

Incaprera (CESWG-PL-S), Dr. C. Linwood Vincent (CEWES-CP-C), Dr. David Moser 

(CEWRC-IWR-R), Mr. William Hansen (CEWRC-IWR-R), and Dr. Mark Dunning (CEWRCIWR-R). 

The manual was subsequently reviewed by engineers and social scientists 

from several Corps Major Subordinate Commands and District Commands. Valuable 

comments and suggestions were received from Mr. Frank McDonald (CENPD-PL-EC), 

Mr. Harry Shoudy (CEBRH), Dr. C. Linwood Vincent (CEWES-CP-C), Mr. Thomas 

Richardson (CEWES-CD), Mr. Richard Rodakowski (CELMS-PD-U), Mr. Adrian J. 

Combe (CELMN-ED-HC), Mr. Ken Claseman (CESAM-PD-FE), Mr. Matthew Laws (CESAMPM), Ms. Mona J. King (CESAM-PD), Mr. J. Thomas Jarrett (CESAW-EN-C), and Ms. 

Anna Zacher (CESPL-PD-CS). The final report was drafted by Mr. L. Leigh 

Skaggs and Mr. William J. Hansen of IWR. 

iv 
TABLE OF CONTENTS 

PREFACE . . . . iii 

LIST OF TABLES viii 

LIST OF FIGURES viii 

CHAPTER I 

INTRODUCTION . . . . . . . . 1 

PURPOSE AND OBJECTIVES 1 

SCOPE . . . . . . . . . 2 

INTENDED AUDIENCE . . . 3 

NATIONAL ECONOMIC DEVELOPMENT (NED) BENEFITS 4 

OTHER ACCOUNTS . . . . . . . 6 

ENVIRONMENTAL QUALITY . 6 

REGIONAL ECONOMIC DEVELOPMENT 6 

OTHER SOCIAL EFFECTS . . . . 7 

INTERRELATIONSHIP WITH OTHER MANUALS 7 

INTERFACE WITH OTHER DISCIPLINES 14 

OVERVIEW OF REMAINDER OF MANUAL 14 

CHAPTER II 

STORM CONDITIONS AND SHORELINE RESPONSE 17 

INTRODUCTION . . . . . 17 

DEFINITIONS . . . . . . 18 

BASIC COASTAL PROCESSES 25 

WAVES . . 25 

TIDES . . . . . . 25 

CURRENTS . . . . 26 

LITTORAL TRANSPORT 26 

STORMS . . . . . . 28 

TSUNAMIS AND EARTHQUAKES 28 

LAKE LEVELS . . . 29 

SHORELINE RESPONSES . . 29 

SHORELINE EROSION 30 

STORM DAMAGE 35 

FLOODING . . . . 36 

COASTAL ENGINEERING CONSIDERATIONS 37 

STORM CONDITIONS 38 

Waves . . . . . . . . . 38 

Storm Surge . . . . . . 39 

DETERMINING EXTREME STORM EVENT FREQUENCY 41 

SHORELINE GEOMETRY . . . . . . . . . . . 41 

LONG-TERM EROSION . . . . . . . . . . . . 42 

RELATIONSHIP OF SHORELINE ANALYSIS TO NED BENEFITS EVALUATION 43 

MODELS OF SHORELINE CHANGE . . . . . . . 44 

HISTORICAL SHORELINE CHANGE METHOD 44 

PREDICTIVE MODELS . . . . . . . . . 45 

v 
CHAPTER III 

DESCRIPTION OF PROJECTS AND BENEFITS 

AUTHORITIES . . . 

OVERVIEW ........ . 

TYPES OF PROJECTS . . . . . SHORELINE ENGINEERING 

Beach Nourishment 

Groins . . . . . 

Seawalls, Bulkheads, and Revetments 

Offshore Breakwaters 

Sand Bypassing . . . . . . 

Dune Building . . . . . . . 

BUILDING AND LAND USE MANAGEMENT 

Setback Requirements 

Relocation . . . . . . . 

Construction Requirements 

Land Acquisition . . . . 

BENEFIT CATEGORIES . . . . . . . . . STORM DAMAGE ALLEVIATION BENEFIT CATEGORIES 

Wave Damage Reduction Benefits 

Inundation Reduction Benefits 

Physical Damage . . . 

Non-Physical Damage . . . . . 

Other Benefits . . . . . . . 

EROSION PROTECTION BENEFIT CATEGORIES 

Loss of Land 

Structural Damage Prevention 

Emergency Costs . . . . . . . 

Reduced Maintenance Of Existing Structures 

Incidental Benefits . . . . . . 

Enhancement Of Property Values 

SYSTEMS ANALYSIS AND DOWNDRIFT IMPACTS 

CHAPTER IV 

ESTIMATING NED BENEFITS . . . . . . 

STEP ONE: DELINEATE THE STUDY AREA 

EXAMPLE . . . . . . . . STEP TWO: DEFINE THE PROBLEM 

EXAMPLE . . . . . . . 

STEP THREE: SELECT PLANNING SHORELINE REACHES 

EXAMPLE ............... . STEP FOUR: ESTABLISH FREQUENCY RELATIONSHIPS 

EXAMPLE . . . . . . . . . . STEP FIVE: OUTLINE AREA AFFECTED 

EXAMPLE .... ' ..... . STEP SIX: INVENTORY EXISTING CONDITIONS 

EXAMPLE . . . . : . . . . . . . . 

STEP SEVEN: DETERMINING MOST LIKELY WITH- AND WITHOUT-PROJECT 

CONDITIONS . . . . . . . . . . . . FACTORS TO CONSIDER . . . . . . . . Response to Long-Term Erosion 

Response to Storm Damage 

vi 

51 

51 

52 

52 

53 

53 

54 

54 

56 

57 

58 

58 

59 

60 

61 

61 

62 

62 

62 

62 

63 

65 

67 

68 

68 

68 

69 

69 

69 

70 

71 

75 

76 

79 

79 

81 

82 

85 

86 • 

89 

93 

94 

94 

95 

96 

98 

98 

99 
DATA SOURCES . . . . . . . . . . . . . . . . . . . . . DISTINCTION BETWEEN STORM AND LONG-TERM EROSION DAMAGE 

EXAMPLE ............. . STEP EIGHT: DEVELOP DAMAGE RELATIONSHIPS 

GENERALIZED FUNCTIONS . . . . . 

DAMAGE VALUATION . . . . . . . . . 

EVALUATION OF COMMERCIAL LOSSES. . 

EVALUATION OF DIRECT PHYSICAL LOSSES 

EVALUATION OF LAND LOSS . . . . . 

EVALUATION OF PUBLIC DAMAGES 

EVALUATION OF NON-PHYSICAL LOSSES 

EXAMPLE . . . . . . . . . . . . . CALCULATING BENEFITS . . . . . . . . . 

STEP NINE: CALCULATE DAMAGE-FREQUENCY RELATIONSHIPS 

TRADITIONAL TECHNIQUE . . . . . . . . MONTE CARLO TECHNIQUE . . . . . . . . 

EXAMPLE .............. . STEP TEN: CALCULATE EXPECTED ANNUAL DAMAGES 

TRADITIONAL TECHNIQUE . . . . . . . . 

MONTE CARLO TECHNIQUE . . . . . . . . 

EXAMPLE .............. . STEP ELEVEN: ESTIMATE STORM DAMAGE REDUCTION AND EROSION 

PREVENTION BENEFITS . . . . . . . . . 

EXAMPLE ................... . Storm Damage Reduction Benefits. . . . . 

Erosion Prevention Benefits . . . . . . . 

Benefits from Reduction of Public Damages 

Other Benefits 

Summary of Benefits . . . . . . . . . . . 

CHAPTER V 

DOCUMENTATION . . . . . 

PLANNING REPORTS 

TYPES OF REPORTS 

FEASIBILITY REPORTS 

REEVALUATION REPORTS 

SUPPORTING DOCUMENTATION 

DETAIL AND DISPLAY 

DETAIL 

DISPLAYS 

.. 

APPENDIX A: COASTAL STORM DAMAGE AND BEACH EROSION CONTROL 

POLICIES AND AUTHORITIES . . . . . . . . . . 

APPENDIX B: AN EXAMPLE OF NED ECONOMIC BENEFITS ANALYSIS 

APPENDIX C: AN EXAMPLE OF SHORELINE DAMAGE ASSESSMENT 

APPENDIX D: AN EXAMPLE OF THE USE OF MONTE CARLO ANALYSIS 

vii 

. . 

'. 

.' 

100 

101 

103 

105 

111 

111 

113 

114 

114 

116 

117 

118 

120 

122 

123 

123 

124 

128 

128 

129 

130 

131 

131 

131 

133 

133 

134 

134 

135 

135 

135 

136 . 138 

138 

139 

139 

139 

145 

157 

253 

267 
LIST OF TABLES 

Table 1. CAUSES OF EROSION ....... . 30 

Table 2. POTENTIAL DATA SOURCES BY SUBJECT 101 

Table 3. VARIABLES THAT INFLUENCE DAMAGE RELATIONSHIPS 109 

Table A-I. SHORE OWNERSHIP AND LEVELS OF FEDERAL PARTICIPATION 150 

LIST OF FIGURES 

Figure 1. COASTAL AREA TERMINOLOGY . . . . . . . 

Figure 2. SCHEMATIC DIAGRAM OF STORM WAVE ATTACK 

ON BEACH AND DUNE 

Figure 3. RUBBLE-MOUND GROINS 

Figure 4. DETACHED BREAKWATER 

Figure 5. PLANNING REACHES AND LITTORAL CELLS 

Figure 6. COMBINED EXCEEDANCE FREQUENCY CURVE, 

WAVE HEIGHT AND TIDE . . . . . . . 

Figure 7. MAXIMUM RECESSION-FREQUENCY CURVES FOR COMBINED 

. ,19 

34 

55 

57 

78 

....•... 87 

NORTHEASTERS AND HURRICANES . . . . . . . . . . . . . . . 92 

viii 
CHAPTER I 

INTRODUCTION 

PURPOSE AND OBJECTIVES 

The purpose of this manual is to serve as a comprehensive guide for 

calculating National Economic Development (NED) benefits primarily for coastal 

and lake shore storm damage reduction and shore protection projects. This 

document presents selected, specific procedures for the entire process of 

benefit estimation. It is intended to serve as a reference guide to questions 

posed by the economic analyst. As a practical guide, the manual attempts to 

emphasize "what to look for" and "what to do," rather than "why do it." 

Suggestions from economists, planners, coastal engineers, and other reviewers 

within the U.S. Army Corps of Engineers (Corps) were incorporated. 

The procedures found in this manual are not the sole methods by which 

analyses may be performed and regulations and guidance followed. There are 

many valid ways to execute the necessary analyses. There are more 

uncertainties and variables in coastal storm damage prevention and beach 

erosion control studies than with most other types of planning studies. Each 

study can be considered unique because of the varied interactions of storms, 

coastal shapes, tidal fluctuations, coastal geology, and offshore geometry. 

Methods should be selected according to requirements of the type of project 

and planning document, local conditions and needs, availability of 

information, funding level to perform the study, and procedures that have been 

successfully employed within the District or by others in the past. 

The fact that a particular procedure is not referenced in this document 

should not be construed as disapproval of that procedure. To the contrary, a 

1 
general theme woven into the comprehensive nature of this document is to 

encourage innovation of procedures. 

This manual is based on the conceptual framework of the Economic and 

Environmental Principles and Guidelines for Water and Related Land Resources 

Implementation Studies (P&G). It neither duplicates nor supersedes P&G, but 

rather elaborates and provides' references for how the guidance of that 

document can be carried out. It is part of a series of NED Procedures 

Manuals, including the Urban Flood Damage Manual (IWR Report 88-R-2), the 

Agricultural Flood Damage Manual (IWR Report 87-R-lO), and the Recreation 

Manual, Volumes I and II (IWR Reports 86-R-4 and 86-R-S). This manual often 

refers to other manuals in the series, and the user should be familiar with, 

or have access to, these reports. 

SCOPE 

This manual is limited to discussion of procedures for estimating the 

economic affects of coastal storm damage and erosion and computing NED 

benefits for shore protection projects. Many of the damaging forces also act 

upon harbdrs, marshes, and other wetlands. Although there has been no attempt 

to specifically address those areas in this manual, many of the techniques 

described would still be applicable. 

The report covers all stages of the planning process. As such, a 

summary of coastal processes and discussion of some shoreline change models 

are included, but only to assist in communication between economists, coastal 

engineers, and other planners. This discussion should not be construed as an 

2 
attempt to supplant other sources of coastal information, such as the w.ellaccepted Shore Protection Manual (SPM).l 

The procedures covered in this manual are applicable to reconnaissance 

reports, Continuing Authority detailed project studies, pre-authorization 

feasibility reports and other economic studies. The methodology used in 

preparing these reports will differ only in detail. 

INTENDED AUDIENCE 

The authors of this volume did not expect that analysts would be 

assigned to a coastal storm damage study without some exposure to more 

traditional flood control studies. It is assumed, therefore, that the reader 

will have some knowledge of such concepts as flood frequency, depth-damage 

functions, plan formulation and benefit evaluation. 

The manual is primarily designed for economists and planners concerned 

with economic analysis of Corps coastal storm damage projects. Planners, 

particularly project managers, must be able to understand and expl~in .the 

process of benefit calculation, and the manual provides information to help 

determine which alternatives are promising enough to carryon to the later 

planning phases. This report should also be useful to hydrologists, hydraulic 

engineers and anyone else involved in shore protection or coastal storm damage 

issues. Distribution to non-Federal sponsors is encouraged whether or not 

they intend to take an active part in the economic analysis. 

1 Coastal Engineering Research Center, Shore Protection Manual, 

(Vicksburg, Mississippi: Waterways Experiment Station, U. S. Army Corps of 

Engineers, 1984). 

3 
NATIONAL ECONOMIC DEVELOPMENT (NED) :BENEFITS 

National Economic Development benefits are defined by P&G as increases 

in the economic value of the goods and services that result directly from a 

project. NED benefits are increases in national wealth, regardless of where 

in the United States they may occur. The NED measurement concept differs from 

regional analysis in the sense that in the NED approach, transfers from one 

region to another become zero unless an efficiency gain is produced for the 

nation as a whole. It follows that a project may be economically attractive 

from the regional perspective, but unwise from the NED view. In contrast, 

because problems or projects may impact areas many miles away, a .project that 

is highly attractive from the NED perspective may not look as attractive from 

the viewpoint of the local sponsor.2 

Because our concern is with the Federal interest, the NED analysis 

counts all benefits and all costs wherever they occur. Therefore, to the 

extent there are economic effects other than those specifically intended, they 

must be identified and taken into account. As an example, if shore. protection 

has an impact on recreation use, this must be considered and displayed even if 

recreation is not a project purpose. 

NED costs are the opportunity costs of diverting resources from another 

source to implement the project. Uncompensated economic losses from 

detrimental proj e.ct effects are also economic costs. As an example, if a 

project indicates mitigation is needed but incremental cost analysis finds 

some project effects will not be fully mitigated, the unmitigated losses will 

be evaluated and included as an economic cost in addition to cost of the 

2 In this case, it may be appropriate to expand the scope of the "local 

sponsor" either to more communities, or to a larger body, such as a county or 

a state agency. 

4 
mitigation plan. Conversely, if measures associated with a project have 

effects above those required to maintain the status quo and result in 

enhancement, the net gain should be counted as a benefit. A project is 

considered economically feasible if the NED benefits are greater than the NED 

costs. The benefit cost ratio would then be greater than one. 

The project with the highest net NED benefits (but not necessarily the 

highest benefit cost ratio), which is otherwise feasible from an engineering 

standpoint, environmentally sound, and publicly acceptable, is the NED plan. 

Specifically, the NED plan should be formulated in consideration of four 

criteria: completeness, the extent to which a given alternative plan provides 

and accounts for all necessary investments or actions to ensure the 

realization of the planned effects; effectiveness, the extent to which an 

alternative plan alleviates the specified problems and achieves the specified 

opportunities; efficiency, the extent to which an alternative plan is th~ most 

cost effective while protecting environmental resources; and acceptability, 

the compatibility of an alternative plan with existing laws, regulations, and 

public policies, and acceptance by the public and state and local entities. 

The NED plan is formulated in detail throughout the planning process 

(beyond the reconnaissance phase) and is given highest priority in selecting a 

Corps recommended plan. Local sponsors may request a plan other than the NED 

plan be implemented. However, in addition to cost sharing the NED plan, any 

incremental costs over the NED plan would be borne by the local sponsor. 

5 
OTHER. ACCOUNTS 

While four .accounts are described by the .P&G, this manual specifically 

addressel:l only the fjfED account. 'nle other three accounts (environmental. 

quality, regional economic qevelopment, and other social effects) contribute' 

to good planning, and are briefly described below. 

ENVIR~AL 9l1ALITX 

Environmental, Quality (EQ) effects. a:re very important. to plan 

formula.tion .•. The N.ational Environmental Policy Act of 1969 (NEPA), PL 91..,.90, 

requires that an environmenta.l impact statement assess the significant changes 

in the environment that would result from an investment of Federal funds. EQ 

effects are assessed as to their magnitude, location, duration, reversibility, 

fr~qq.enqy.,and.:t1;le long::-term productivity of an area 's value as a resource. 

The objectives of environmental evaluation are to affect.the formulation of 

plans.t.o ayoi4 detrime:ntal impacts,totake. advantage of opportunities for 

enhancemellt and protection of. resources, and to aid in dete.rmining a 

mitigation plan, that .. will offset environmentally detrimental proj ect. effects. 

Guidelines,t,o environmental quality. evalua.tion can be found in Chapter Three 

.of,E&G. a'(ld .Chapter Seven; of Engineering Regulation (ER) 1105-2 .... 100, 28 

December 1990. 

REGIONAL ECONOMIC DEVEUOPMENT 

'. Regional Economic .. Development (RED) benefits refer to economic gains 

from ,a project,in a. specific geographic area. These gains are me~sured by the 

net increase~.of income and. employment. RED benefits include transfers or 

redls,tributionof wealth. from other regions of the country as well as . 

6 
increases in national wealth incident to that specific region. While RED 

benefits not otherwise included in NED benefits cannot be used in determining 

the costs and benefits of the NED plan, they can be extremely helpful to the 

local sponsor in assessing the value and financial feasibility of the project. 

A detailed description of the RED aC!oountcan be found in SR 1105-2-100, pages 

5-20 ... 5-22. 

A complete evaluation of the regional economic development account 

should cOr'lsider the net gain to regional income and employment. The 'ValUe of 

economic activity that would not occur because of the project should be 

subtracted in the computation of net RED benefits. 

omER SoclAL EFFECTS 

The Other Social Effects (OSE) account includes those impacts which are 

not incorporated in the other three accounts, but are still important enough 

to have a bearing on the decision-making process, OSE impacts are primarily 

impacts that can be quantified, but are not amenable to assignmer'lt of any 

monetary value. OSE includes changes in risks to life and health, community 

vitality, displacement, fiscal health, as well as the geographic and 

demographic distribution of income and employment impacts. The OSE accour'lt is 

further described in ER 1105-2-100, pages 5-22 - 5·23. 

INTERRElATIONSHIP VIm omER MANUALS 

This manual is limited to discussion of procedures for estimating the 

national economic effects of computing NED benefits for shore protection and 

storm damage reduction projects. These projects may range from small, 

single-purpose projects to parts of major, mUlti-purpose projects. Included 

7 
is a discussion of some of the advantages and drawbacks of various benefit 

calculation methods. Much of the methodology for gathering, analyzing, and 

presenting basic damage information is contained in the Agricultural and Urban 

Flood Damage NED manuals. We have attempted to minimize duplication of that 

information and concentrate on areas unique to shore protection and storm 

damage reduction. Major areas of difference are described below. 

A. CAUSE OF FLOODING - Although not a prerequisite to coastal flooding, 

ocean effects eroding the natural protection (e.g., dunes, beach or 

barrier islands) over a period of months or years may increase the 

susceptibility of a shoreline to flooding or increase the severity of 

flooding from a given storm event. The cause of coastal flooding is 

often related to ocean water being driven overland by the force of wind, 

waves, and high tides. Rainfall, however, may also have a major impact 

on coastal flooding when conventional drainage or storm sewer systems 

are blocked by storm surge. Rainwater ponds during the storm duration 

and releases slowly as the storm surge drops. Flood damages in riverine 

environments are normally caused by precipitation and snowmelt which 

result in high flows in channels of insufficient capacity. Natural 

protection (i.e., channel capacity) is usually assumed to remain 

relatively constant over the period of analysis. 

B. FLOOD VELOCITY - In riverine flooding, velocity is determined by 

stream gradient, flood plain characteristics, natural storage and the 

volume of water. Coastal storm flood velocity is determined by wind and 

tidal action and can have potentially significant effects, especially 

8 
where such natural or man-made features as closely-spaced buildings, 

beach access roads, parallel jetties, and discontinuities in shore 

protection structures form conduits for the passage of flood waters. In 

addition, high winds accompanying the coastal flood velocities often 

cause catastrophic property damage not directly related to flood waters 

or preventable by controlling flood impacts. 

C. FLOOD PREDICTABILITY - In most coastal areas, erosion and storm 

damage records are less frequently available and less reliable than 

those for stream flows. Coastal storms, including hurricanes, can be 

very localized and arise with little warning. Hurricane warning 

forecasts and evacuation plans are well developed in many coastal areas, 

but the na.ture of these storms can promote uncertainties in terms of 

location of landfall, maximum winds, and maximum sutge flood heights. 

Another category of coastal storms, northeasters, are typically broad in 

their area of influence and follow general storm tracks that, while not 

predictable, can be anticipated. 

Flood predictability in riverine flooding is characterized by, and 

displayed in, frequency curves or tables. The display indicates how 

often a given annual peak flow or stage is exceeded. The more 

historical information from past floods available, the more certainty 

there is in the frequency analysis. Gathering and recording information 

on precipitation, temperature and river levels is more institutionalized 

than gathering and recording of coastal storm events. Coastal events 

may be linked to .a combination of events such as local wind-driven 

9 
waves, ocean swells, extremely high tides, and high river flows in 

adjacent coastal streams. 

D. EROSION LOSSES OF A SINGLE EVENT - River bank erosion is 6ften not 

storm- or flood-related. Bank erosion in meandering streams, for 

example, is likely to be very evident during low flow periods. Erosion 

can be flood-related in the sense high flows can result in saturation of 

materials, washouts, bank cave-ins, loss of natural protection, 

overtopping of armor, or avulsion (the sudden cut off of land by floods, 

currents, or ehanges in the course of a river). In river flooding it is 

difficult to establish a reliable link between a predicted flow or water 

level and consequential erosion, while water levels and storm durations 

are major factors in coastal erosion models. Erosion is identified with 

/ 

a single event against a background of a long-term series of events over 

time. 

E. LONG~TERM EROSION LOSSES - In the riverine environment, erosion 

(usually bank erosion) is sometimes predicted as a function of flow, but 

more often is a result of repeated cycles of high and low flows over a 

period of years. In the coastal environment, beach profiles often shift 

both in and out seasonally as well as in response to storms, making 

annual (and seasonal) changes a "normal" situation. This long-term 

normal situation is an appropriate and necessary consideration in 

establishing the without-project condition, and against which stormrelated changes must be compared. 

10 
F. DOUBLE COUNTING OF DAMAGE PREVENTED ON LANDS LOST TO EROSION -

Double counting of damages is usually not a major factor for flood 

damage studies, but may be a major issue for storm damage or erosion 

prevention s.tudies. Double counting is usually a cOrtsequence of first 

counting a property as damaged by a storm event ~nd also counting it as 

damaged in the long-term erosion category. Most double counting can .be 

avoided by establishing stage-damage relationships for various points in 

the planning period (usually :> or 10 years as appropriate to the 

severity of the long-term erosion problem). If the st~ge-damage 

relationship is periodically recalculated .to subtract property lost to 

erosion, then average annual inundation damages will not be claimed for 

property no longer in the inventory of damageable improvements. 

G. TIDAL EFFECTS - Tides impact the flooding problem in riverine flood 

studies in a predictable manner since the effects are usually taken into 

account in backwater calculations. Tides may also be a major factor in 

storm damage and erosion loss studies, but tidal levels are just one 

parameter incorporated into coastal stage-frequency curves. 

Determination of frequency of water surface elevation must consider 

effects of wind, tide, precipitation, and any other impact, not just 

precipitation and runoff. 

H. SALT-WATER EFFECTS - The effects of salt water are nearly always a 

factor with coastal .storm flood damage studies, although seldom a major 

factor with riverine flooding. 

11 
I. EFFECTS OF SUBSIDENCE AND MARSH DETERIORATION - Natural processes or 

man-made events can cause land subsidence and marsh deterioration. 

While less significant in most inland riverine situations, the long-term 

effects of the decrease in land elevations or sea-level rise are very 

significant in low-lying coastal areas. Coastal storm damage and 

erosion studies will therefore treat subsidence and sea-level rise with 

greater signfficance. The results of the study should frame conclusions 

in a way that demonstrates sensitivity to these issues. 

J. ROLE OF SIMULATIONS IN THE ANALYSIS - Monte Carlo simulation 

(described subsequently in this report) and other simulation techniques 

are convenient procedures in coastal storm damage analysis for weaving 

together the joint probabilities of independent causal events. They 

work well for problems with multiple variables which can best be 

described by a series of independent probability functions such as 

tides, high winds and other offshore storms, as well as for situations 

where some or all of the variables are interdependent. Traditional 

analysis techniques are usually adequate for most riverine flood damage 

studies where the stage-damage, stage-discharge, discharge-frequency, 

and damage-frequency curves are more easily established. 

K. THE FEDERAL INTEREST - Flood damage prevention problems are clearly 

in the Federal interest where benefits are widespread, and have been a 

long standing priority of the Corps. In contrast, solutions to erosion 

problems are often identified as not being in the Federal interest 

because they are not characterized as storm-related and/or having 

12 
widespread benefits. It is undoubtedly recognized that the benefits for 

erosion and storm damage are often interrelated; frequently long-term 

erosion must be halted to accomplish storm damage prevention. 

Nevertheless, the fact remains that the costs of constructing projects 

for beach erosion control must be assigned to hurricane and storm damage 

reduction and recreation purposes. 3 Therefore, projects which 

demonstrate erosion damage prevention benefits to be storm-related, and 

that the erosion is, to an identifiable extent, storm-caused, will 

likely receive higher priority. 

L. IMPACT ON LAND USE AND LAND VALUE - Coastal storm damage prevention 

can result in an increase in usable beach area, Care must be taken to 

avoid double counting of beneficial effects, such as estimating benefits 

from both enhanced land value and increased recreational value, since 

both are different ways of measuring the same values. Coastal storm 

damage protection projects may either increase or decrease adjacent land 

values. Increases in land values due to a change in land use resulting 

from a project are evaluated as location benefits, while decreases in 

value are project costs. Corps projects are not formulated for land 

development, so it is important to distinguish the portion of benefits 

that are related to land development or enhancement. Widespread 

benefits for multiple users, derived from protection of improvements 

that provide for at least 50 percent of the justification of the 

3 As specified in PL 99-662, Section 103(d). See "Appendix A, Coastal 

Storm Damage and Beach Erosion Control Policies and Authorities" for greater 

detail. 

13 
project, will be a sq1id basis for showing Federal interest and a Corps 

role. 

INTERFACE WITH OTHER DISCIPLINES 

Coastal storm damage and erosion studies require very close coordination 

between the study manager, the coastal engineer, the economist, and the 

environmental specialists involved in the study. Assumptions made by any of 

the participants may affect the other disciplines more than with any other 

type of study. For example, if the economist assumes that an individual owner 

will construct a bulkhead to protect part of his property, the bulkhead may 

affect the littoral transport and erosion rates updrift or downdrift, thereby 

potentially affecting nearby development and/or any protective measures under 

consideration. Similarly, the coastal engineer may determine that the 

bulkhead will not be effective at all, in which case the damages assumed in 

the without-project condition and for any proposed project will be affected. 

If the economist assumes a structure will be removed or relocated rather than 

being replaced or repaired, then long-term erosion may be affected, or it may 

cause the environmentalist to further assume long-term development of some 

significant environmental effect which would not otherwise occur. 

OVERVIEW OF REMAINDER OF MANUAL 

Chapter II. Chapter II gives a brief introduction to the principles of 

coastal engineering and shoreline responses to storms and long-term erosion. 

It is intended only as a source of background information for those with 

limited exposure to coastal storm damage prevention and shore protection 

studies and the relevant terminology. Those readers interested in a more 

14 
detailed technical presentation should consult the Coastal Engineering 

Research Center's Shore Protection Manual. 

Chapter III. Chapter III provides a basic outline of the types of 

projects and various benefit categories. Emphasis is placed on differences 

between storm and long-term erosion damage. Brief descriptions of alternative 

types of projects are provided again, only as background information, to 

improve communication: 

Chapter IV. Chapter IV provides a step-by-step guide for estimating NED 

benefits. Eleven discrete steps are described, from delineation of the study 

area and establishing present and future conditions both with- and withoutproject to calculation of benefits. A practical methodology for conducting 

each step is explained, including how both the traditional evaluation 

procedures and simulation (Monte Carlo) methodologies can be used. An example 

of the methods employed in an actual storm damage reduction and beach erosion 

control project is presented. 

Chapter V. Chapter V discusses the suggested minimum amount of 

documentation needed for various types of reports and studies. 

Appendices A through C provide additional technical information on 

coastal storm damage and beach erosion control policies and authorities; an 

example of NED economic benefits analysis from an actual planning study; and 

an example of shoreline damage assessment using Monte Carlo simulation from 

another planning study. 

15 
CHAPTER II 

STORK CONDITIONS AND SHORELINE RESPONSE 

INTRODUCTION 

This chapter describes the basic coastal processes and the coastal 

engineering principles and models used in evaluating storm damages and 

long-term erosion. The definitions and physical mechanisms are explained in 

relatively non-technical terms to provide some of the information necessary 

for non-coastal specialists to be able to work with coastal professionals to 

assess coastal storm damages and erosion. It is not intended to supplement or 

act as a substitute for the Shore Protestion Manual (SPM)l or other technical 

references. The reader is encouraged to refer to that manual for more 

detailed explanations. 

The field of coastal engineering encompasses a variety of disciplines, a 

wide range of environmental conditions, and more uncertainty than most 

hydrologic engineering. Shorelines respond dynamically to ocean tidal forces, 

Great Lakes water levels, wind-generated waves, and large-scale currents. 

Cycles of erosion and accretion may vary from hours to decades. It is 

important to understand both the coastal processes and the shoreline responses 

before attempting an engineering solution. 

One goal of this chapter is to provide sufficient information to enable 

economists and planners to understand the engineering solutions proposed by 

the coastal professionals. Because of the technical nature of much of the 

discussion in this chapter, a short glossary is provided to standardize the 

1 Coastal Engineering Research Center, Shore Protection Manual, 

(Vicksburg, Mississippi: Waterways Experiment Station, U. S. Army Corps of 

Engineers, 1984). 

17 
definitions of some common terms. Figure 1 provides a general illustration of 

some of the technical terms found in the glossary. 

DEFINITIONS 

Accretion - The buildup of land on a beach ,either due to natural forces 

(deposition by water or air) or in response to structures or fill. 

Backshore - The part of the shore, (between foreshore and dunes) acted upon by 

waves only during severe storms, especially when combined with 

exceptionally high water. The backshore is composed of berms. 

Bathymetry - The measurement of the depths of water in oceans, seas, and lakes 

and the information derived from such measurements. 

Beach - The narrow strip of shore land in immediate contact with the sea 

is called a beach when unconsolidated sediments, usually sand, are 

present. 

Beach Fill - The artificial building up and/or widening of the beach by direct 

Berm -

Breaker -

placement of fill material on the shore. 

A nearly horizontal part of the beach formed by the deposit of 

material by wave action. Some beaches have no berms, others have 

one or several. 

A breaking wave, for example, on a shore or over a reef. 

Breakwater - A structure built to block or reduce the wave energy in the lee 

of the structure thereby reducing the wave energy available to 

attack the beach or shore. 

Bulkhead - A wall-like structure usually built of wood, steel, or concrete, 

designed primarily to retain or prevent sliding of the upland 

area. Bulkheads are often used in harbor and sheltered water 

18 
I-' 

\0 

Coast 

Dune 

Beach 

Coastal Area 

Beach or Shore Nearshore Zone 

(Defines area of nearshore currents) 

Backshore Foreshore Inshore or shoreface 

BI u f f 

(Extends through breaker zone) 

or 

Surf Zone 

High water level Crest 

ordinary low water level 

Plunge point I 

Figure 1. Coastal Area Terminology 

O

Bo

Source: Shore Protection Manual, (Vicksburg, MS: Waterways Ex

Station, 1984). 
areas to protect the upland from wave and current action. 

Deflation - The removal of loose material from a beach or other land surface 

by wind action. 

Diffraction - The transmission of energy laterally along a wave crest. When 

waves approach a barrier, such as a breakwater, diffraction is 

manifested by the creation of waves in the sheltered region within 

the barrier's shadow. 

Dune -

Erosion -

Fetch -

A common feature of sandy coasts composed of wind-blown sand, 

generally in long ridges paralleiing the shore and usually above 

the level of storm waves. 

The loss of beach or dune material by the action of wind, waves, 

and currents. 

The area in which waves are generated by a wind having a fairly 

constant direction and speed. 

Foreshore - The part of the shore lying between the upper limit of wave wash 

at high tide and the ordinary low-water mark, that is ordinarily 

traversed by the up rush and backrush of waves as the tides rise 

and fall. 

Groin -

Headland 

Hindcast 

A structure usually built perpendicular to the shore to stabilize 

shoreline position and minimize erosion by trapping longshore 

moving sediment. 

A high, steep-faced promontory extending into the sea. 

The determination through empirical relations or numerical models 

of wave heights, periods, directions, and such factors as storm 

surge from historical weather charts or other historical records. 

20 
Inshore Zone - The zone of variable width extending from the low water line 

through the breaker zone. 

Jetty - A structure usually built at the mouths of rivers or tidal inlets 

to stabilize a navigation channel and assist in maintaining 

project depths by preventing shoaling of littoral materials. 

Littoral transport - The movement of sedimentary material due to waves and 

currents either parallel to the shore (longshore transport) or 

perpendicular to the shore (cross-shore or on-offshore transport). 

The sedimentary material per se is called littoral drift. The 

seaward limit of sediment transport defines the littoral zone. 

Littoral cell - An area of the coast defined by natural headlands or features 

which limit littoral transport into or out of the cell. 

Morphology - The shape of the shore, nearshore, and offshore surface contours. 

Neap Tide - A tide occurring every two weeks having a minimum range between 

successive high tides and low tides. 

Nearshore Zone - An indefinite zone extending seaward from the shoreline well 

beyond the breaker zone. It defines the area of nearshore 

currents. 

Overwash - That portion of the wave uprush that carries over the crest of a 

berm or a structure. 

Plunge Point - The final breaking point of the waves just before they rush up 

on the beach. 

Reach - The primary economic analysis sub-unit. The shoreline and 

associated upland areas are divided into reaches throughout which 

geomorphic structures, erosion conditions, or human development 

patterns can remain relatively constant. 

21 
Recession - In this manual,the landward movement of the shoreline during a 

storm due to the transport of sediment, excluding the effect of 

post-storm accretion. Recession may also refer to the net 

landward movement of the shoreline over a specified period of 

time. 

Refraction - The bending of waves by currents or underwater surface contours. 

Revetment - A veneer of stone, 'concrete, or other material built along a bank 

or shore to prevent loss of land and damage to landward structures 

caused by wave action or currents. 

Riprap -

Runup -

Rubble orquarrystone, usually well graded within a wide size 

limit, randomly placed along a structure or shore to prevent wave 

and current erosion. 

The up rush of water along a beach or structure due to breaking 

waves. If this exceeds the height of the beach or structure, 

overtopping occurs. 

Shoaling - The gradual process of a bay, inlet, or channel becoming 

shallower, usually caused by sediment deposition. 

Shoaling coefficients - The ratio of the height of a wave in water of a given 

depth to its height 'in deep water. 

Seawall - A structure similar to, but more substantial than, a revetment. 

It is usually constructed of pour-in-place concrete. Seawalls are 

generally built in areas where a high degree of protection is 

warranted. 

Sediment budget - The process of estimating or quantifying the sediment 

contributions and losses within a littoral cell to determine if 

beach erosion or a,ccretion should naturally occur. 

22 
Seiche -

Setup .,.. 

An oscillation of the surface of an enclosed or semi-enclosed body 

of water that varies in period from a few minutes to several 

hours. 

Increase in water surface elevation at the shoreline independent 

of astronomical tides due to onshore transport of water by wave 

action (wave setup), or winds (wind setup). 

Spring Tide - A tide occurring every two weeks having a maximum range betwe.en 

successive high and low tides. 

Storm surge - A rise in local water level above the astronomical tide level 

due to a combination of wind and low atmospheric pressure during a 

storm or hurricane (also called storm tide). 

Storm Track - The path fol-lowed by the center of low pressure of a storm. 

Surf Zone - The area between the outermost breaker and the limit of wave 

uprush. 

Surge Barrier - Structures built across the entrances of bays, lagoons, 

sounds, and estuaries to block the progression of storm setup or 

surge into these areas. These barriers generally consist of dikes 

with circulation and/or navigation openings which are left open 

during fair weather and closed when coastal storms threaten to 

flood the area. 

Swell -

Tide -

'Wind-generated waves that have traveled out of their generating 

area, usually characterized by regular, long periods and flat 

crests. 

The periodic rise and fall of the ocean caused by the 

gravitational forces of the sun and the moon; The maximum height 

reached by water during each rising tide is called. high tide or 

23 
Tsunami -

Waves -

high water and the minimum level is called low tide or low water. 

On some coasts this occurs once a day (diurnal tide) while on 

other coasts this occurs twice a day (semi-diurnal tide). When 

one high tide is higher it is called Higher High Water (HHW) and 

the lowest tide is called Lower Low Water (LLW). When HHW or LLW 

is averaged over a 19-year period the datum is called Mean Higher 

High Water (MHHW) or Mean Lower Low Water (MLLW). 

A long period ocean wave produced by an undersea earthquake or 

volcanic eruption, often mistakenly called a tidal wave. 

Changes in the elevation of water in the ocean caused by the 

motion of currents and wind action. The average height of the 

highest one-third of the waves usually measured by observing the 

vertical distance between a crest and the preceding trough is 

called significant wave height. The wave conditions to which a 

shore or structure will be subjected is usually derived by 

combining deepwater wave statistics for height, period, and 

direction with computed refraction and shoaling coefficients. 

Wave Height -The vertical distance between a wave crest and the preceding 

trough. 

Wavelength - The horizontal distance between similar points on two successive 

waves measured perpendicular to the crest. 

Wave Period - The time it takes two successive wave crests to pass a fixed 

point. 

24 
BASIC COASTAL PROCESSES 

This section describes the physical environment that is responsible for 

shoreline responses such as erosion, flooding, storm damages or accretion. 

Much of this material is extracted from the Shore Protection Manual or other 

Corps publications. Basic coastal processes include such forces as waves, 

tides, currents, littoral transport, storm surges, seiche, hurricanes; 

tsunamis and the interaction of these forces with shore features and other 

factors affecting shore stability. 

WAVES 

Most of the energy delivered to the shore by the ocean originates from 

the wind acting on the ocean to produce waves. Wave characteristics are 

determined by the wind direction, wind speed, wind duration, how far the wind 

blows over water, and how far the wave travels before reaching land. Waves 

generated locally by wind action are called sea; those generated elsewhere, 

swell. Sea waves are generally steep (high ratio of wave height to length), 

while swell are usually flatter. In cases where sea and swell exist 

simultaneously, the sea will have shorter periods. Both can have large, 

damaging heights. 

TIDES 

Changes in water level elevations due to gravitational forces of the 

moon and sun occur regularly enough to predict mathematically for most points 

on the coast. The tide usually has two high levels and two low levels per day 

(semi-diurnal) or one high and one low per day (diurnal). The range from high 

to low tide varies with time of the month or season. Spring tides have the 

25 
highest ~ange ~ud nea~ tides the lowest. Tidal range also varies with the 

location along the coast or the distance up a river or estuary from the coast. 

CURRENTS .. 

Curren{:s,can be generated by either winds or waves or may be part of 

largeroc~an.circul~tion patterns. Onshore (a direction landward from the 

sea) or offshor~ (a direction seawardf;-:Qm the land) winds also directly 

produce currents which tend to be at right angles to the winddirection~ 

LongshQr~ currents. can also be produced by waves approaching the shore at an 

o1lngle. Lon$shQre curr.ents are important in the transport of sediment away 

from or towar,dthe. project sit.e. Tidal currents are important in shallow 

water near tidal inlets. River discharge may also produce nearshore currents. 

LITTORAL TRANSPORT 

Littora~. transport, the movement of sedimentary material (Le., littoral 

drift) in the littora1-.~o:he by waves and currents, has a tremendous impact on 

coastal morphology. The process has both a longshore and an onshore-offshore 

component. The former bas an average net direction parallel to the .shoreline, 

whereas the latter has an average net direction perpendicular to the shore. 

The quanti~ication of sedime~t transportation, erosion, and deposition for· a 

selected srg~ent of the c?,ast is, l<n:ow:n as a sediment budget. While the. 

boundaries for the sediment budget are deterxpined by th~ area under study, the 

time scale of interest, and study purposes, separate budgets may be needed for 

distinct littoral cells (e.g., between inlets that separate eroding and 

accreting beach segments). 

26 
Processes that increase the quantity of sediment within the bell are 

called sources, while those that decrease the quantity are called sinks. 

Longshore transport can function as both a source and a sink for the littoral 

cell. Point sources or point sinks (tidal inlets often function as the 

latter) add or subtract sediment across a limited part of the cell. Line 

sources or line sinks (an example of the latter would be wind·trarisport 

landward from the beaches of a low barrier island) add or subtract sediment 

across an extended segment of a littoral cell. In a complete sediment budget, 

the difference between the sand added by all sources and the sartd removed by 

all sinks should be zero. In the usual case, a sediment budget calculation is 

made to estimate an unknown erosion or deposition rate, which is the 

difference resulting from equating known sources and sinks. 

The relative importance of elements in the sediment budget varies with 

locality and with the boundaries of the particular littoral cell. On many 

shores, the gross longshore trartsport rate significantly exceeds other volume 

rates in the sediment budget, but if the beach is approximately in 

equilibrium, this may not be easily noticed. The erosion of beaches and 

cliffs and river contributions are the principal known natural sources of· 

beach sediment in most localities. Inlets, lagoons, and deep watet in the 

longshore direction comprise the principal known natural si"oks for beach 

sediment. Of potential, but usually unknown, importance as either a source or 

a sink is the offshore zone seaward of" the beach. ~ \ 

27 
STORKS 

Whether they are called hurricanes, cyclones, tropical storms, 

northeasters, or other names, storms2 and their associated winds, waves, and 

inundation are responsible for most of the destructive coastal damage and 

short~term erosion that occurs. It is'important to note, however, that major 

storms,such as hurricaI)es, may cause.massive damage and flooding with little· 

accompanying beach.~rosion. Some important characteristics in assessing 

potential storm damage include the storm track, landfall location, storm surge 

elevation, storm intensity, wave height, frequency of occurrence, duration, 

and related meteorological factors such as wind and rainfall. 

TSUNAMIS AND EARTl'IQUAKES 

Tsunam~s, sometimes mistakenly termed tidal waves, are very long-period 

waves generated by seismic events such as earthquakes. The waves are capable 

of traveling thousands of miles from the originating seismic .. event. Tsunamis 

occur rarely, but they can be very destructive to affected coastlines. 

2 The definition of a "storm" is not absolute. According to the Shore 

Protection Manual, a storm is an atmospheric disturbanc.e characterized by high 

winds which mayor may not be accompanied by precipitation. Storms are 

categorized by their wind vel()city and region of origin. For example, 

hurricanes are tropical storms having winds in excess of 73 miles per hour; 

northeasters are extratropicalstorms, having. strong winds (no velocity 

threshold, however) blowing from the northeast quadrant that occur along the 

Atlantic coast of the U.S. 

While there is no universally-accepted set of minimum conditions that 

define storms, in coastal settings a l3torm can b.e defined as a period during 

which wave heights exceed a critical value. In this manual, a generally 

accepted, albeit arbitrary,dis1;:inctiotl between storm damage events and 

erosion damage events is used: a one year exceedance frequency. That'is, 

damages resulting from waves w.ith .exceeqatlce. frequencies of less than or. equal ") 

to one year are characterized as erosion damages, while damages resulting from 

waves with exceedance frequencies of greater than one year constitute storm 

damages. 

28 
Additionally, earthquake events per se are destructive processes that can 

significantly alter the coastal landscapes where they occur. 

LAKE LEVELS 

Lakes have insignificant tidal variations, but are subj ect t:oseasonal' 

and annual hydrologic changes in water level, and to water level changes 

caused by wind setup, barometric pressure variations, and sEdc'he .. 

SHORELINE RESPONSES 

The shoreline responses most often of concern are beach erosion and 

storm damage. Storm erosion refers to the loss of beach or dUne material by 

waves and high water levels associated with storms, while storm damage implies 

physical- damage (other than caused by land loss) to structures and other 

facilities due to any combination of winds, waveS, tides, and intense 

rainfall. Storm damage and erosion occur along other types of shorelines, but 

are more critical on beaches. Beaches can be described by .their material, 

width, slope, and by the presence of features such as bars, dunes, headlands 

or inlets. Beaches may be on offshore barrier islands, on the mainland, 

lakeshores, or along the margins of an estuary -or river. The presence and 

type of beach isa dynamic response to the availability of sediments and the 

ocean forces. Under static conditions the beach can naturally absorb the 

ocean forces and maintain stability. If conditions change, the beach wilt 

become unstable and will erode or accrete in order to re-establish stability. 

For example, if sediment supply is diminiShed <whether caused by man-made or 

natural forces), or abnormal storm conditions occur, -the beach erO'des. 

29 
SHORELINE EROSION 

There are both short-term and long-term causes of shoreline erosion. 

Erosion may be natural or man-induced. The most common type of short-term 

erosion is from storms which can produce rapid, dramatic erosion. Long~term 

eroBionmay be less noticeable, but may ultimately have more severe 

consequences. Table 1 lists the various causes of erosion. 

NATURAL 

MAN-MADE 

TABLE 1 

CAUSES OF EROSION 

SHORT-TERM 

Storm Waves (Large Wave 

Height and/or Short Wave 

Period) 

Storm Surge 

Overwash 

Flooding 

Rip Currents 

Underflow 

Ice Flows (on the Great Lakes) 

Navigation Inlets 

Seawalls, Groins, Jetties, 

and Other Structural 

Features 

LONG-TERM 

Sea Level Rise 

Decreased Sediment Supply 

Deflation 

Littoral Transport Loss 

Sorting of Beach Sediment 

Flooding 

Rip Currents 

Subsidence (Compaction) 

Navigation Inlets 

Seawalls, Groins, and Other 

Structural Features 

Aquifer Depletion 

Damming of Rivers 

Sand Mining 

Dune Destabilization 

Man-induced erosion is commonly unplanned and results from unexpected 

consequences of coastal or upland development. While natural channel 

entrances have a substantial capacity to modify sediment transport in their 

vicinity, artificially dredged channel entrances, structurally modified for 

navigational purposes, have a much greater potential for affecting the 

adjacent shores. Impacts vary with the characteristics of a particular 

entrance. Effects can extend miles from the entrance channel and are greatest 

where there is substantial net longshore sediment transport. Examples of 

30 
significant shoreline erosion caused by structural modification of inlets and 

entrance channels exist at Oc.ean City, Maryland; St .. Mary's River, Georgia; 

and.Port Canaveral, Florida. Primary impacts have included interruption of 

longshore sediment transport. recession or landward migration of down drift 

beaches, and loss of littoral sediments from the nearshore system: Offshore 

disposal of beach-quality sand dredged from inlets acts to compound the 

adverse impacts on adjacent shorelines. The loss of beach materials due to 

sand mining for construction purposes has a similar consequence. 

Long-term erosion from a sealevel rise due to global warming may be 

considered either natural or man-induced. Similarly, subsidence of land 

surfaces also results in beach erosion. A drop in nearshore elevation due to 

subsidence is equivalent to a sea level rise of the same magnitude; the beach 

profile is thrown out of equilibrium by the creation of a sand sink offshore, 

and this induces offshore sediment transport and shore recession. Examples of 

naturally-caused subsidence occur in the Mississippi River delta, where the 

weight of the accumulated sediment causes continued compaction and sinking, 

and in areas of seismic activity, where earthquakes can result in rapid 

downward displacement of the land surface. Man-induced subsidence can be 

caused by the mining of hydrocarbons and by water extraction for agricultural, 

municipal, and industrial uses. An example of subsidence due to the former 

exists in the Terminal Island-Long Beach region in California; an example due 

to the latter at the southern end of San Francisco Bay; and an example of 

subsidence due to both in the Houston-Galveston Bay area, Texas. 

Coastal erosion may also result from man-made modifications in upstream 

river valleys, where the. building of levees and dams for flood and debris 

control, water supply, and hydroelectric power can have unintended detrimental 

31 
effects by cutt~ng off supplies . of s.ediment to the coast. This problem is 

particularly ev!,.de~t on the U.S. Pacific coast, where rivers historically have 

been a maj or so.urce of sand for coastal beaches. Infrequent large floods are 

responsft;>le for depositing large quantities of sand at river mouth deltas. a.nd 

waves and c~rrents act upon this.episodic source, gradually transporting the 

sand along the coast. 

Other. sourc~s of human-induced erosion are shoreline protective works 

such as groins, s.eawalls, and breakwaters, which are built to stabilize 

beaches and control. erosion, but which may actually induce downdrift beach 

.erosion. Because no new sand is created, their purpose is to redistribute. 

sand along and across the be.ach profile. However, this modification of the 

normal. littoral transport mechanism m~y have negative ramifications downdrift. 

While the use of properly engineered structures has proven successful where. 

correctly designed, constructed, and maintained, their effects on adjacent 

shores must be carefully evaluate~. 

Beaches respond to wave action differently under normal and storm 

conditions. When nor~al conditions prevail, the wave energy is easily 

dissipated by the beach's natural defense mechanisms. During storm 

conditions, however, the increased wave energy exerted by the storm requires 

an extraordinary response, such as the sacrifice of large sections of beach 

and dune materi,al through erosion. .In time the beach may recover, but ofte~ 

not w.ithout a permanent loss of this littoral material. 

Under normal wave conditions, the beach's first line of defense is the 

form of the sloping nearshore bottom. Waves break, expending some of their 

energy in turbulence and the tr~nsport of bottom sediment, at a depth 

generally defined by the breaking wave formula (a water depth equal to about 

32 
1.3 times the wave height). Most of the rest ·of the water's energy is spent 

in rushing up the beach slope between normal high and low tides (between th$ 

mean high water and mean low water levels). Above the high tide, beach 

sediment affected by the wind is moved shoreward into dunes .. The result is a 

relatively stable profile (Figure 2A). If there is an increase in the 

incoming wave energy, the beach profile will adjqst tp absorb that energy, 

usually by the seaward transport of beach material to an area where the bottom 

water velocities are sufficiently reduced to cause sediment deposition. 

Eventually enough material is deposited to form offshore bars,. which cause the 

incoming waves to break further seaward, dissipating their energy over a wider 

surf zone. 

The subtle changes in the beach which occur during normal conditions 

may, depending on whether more sediment or beach material is removed or added, 

result in accretion, a stable profile, or erosion. The effects of storms, 

however, are often devastating in terms of shoreline erosion. During a storm 

event, high winds and high water levels (storm surge) combine with steep waves 

which may bypass the offshore bars to break directly on the beach (Figure 2B). 

The increased energy contained in the storm waves is spent eroding part of the 

beach, berm, and sometimes dune (crest recession and lowering in Figures 2C 

and 2D), which are now exposed to wave attack by virtue of the storm surge. 

The eroded material is transported farther offshore where it i.s deposited to 

form a deeper offshore bar. This bar eventually grows large enough to break 

incoming waves, thereby dissipating some of the waves' energy over a wider 

surf zone (Figure 2C). However, this offshore bar may be too deep to affect 

normal waves after the storm, and additional beach material is eroded to 

reestablish the normal offshore bar. Where there is ample sediment supply the 

33 
Profile A - Normal wave action 

Profile B - Initial attack of 

storm waves 

c. 

Profile C - Storm wave attack 

of foredune 

D. 

Profile 0 - Atfer storm wave attack. 

normal wave action 

Prol i Ie A 

___ M.H.W., 

Profile ,A 

Figure 2. Schematic Diagram of Storm Wave Attack on Beach and Dune. 

Source: Shore Protection Manual, (Vicksburg, MS: Waterways Experiment 

Station, 1984), 

34 
beach is rebuilt (accretes) during the period between storms, but if sediment 

supply is limited or storms are too frequent, the beach suffers a net loss of 

sediment. 

At coastal sites having no dunes or low protective dunes, or when the 

storm conditions are particularly severe, the storm surge and wave action may 

succeed in c9mpletely overtopping the dunes causing extensive coastal 

flooding. When this occurs, beach and dune sediments are swept landward by 

the water, and in the case of barrier islands, are deposited as overwash fans 

on the backshore or in the lagoon. This process results in a loss of sand 

from the dynamic beach system. Often, stormoverwash and storm flooding 

return flow will erode enough sand to cut a new tidal inlet through the 

barrier island. Depending on various factors, the new inlet may become a 

permanent feature of the coastline. 

STORM DAMAGE 

In addition to beach erosion, storm damage may occur to any structure 

located close enough to the water to be undermined or directly attacked by 

waves. In areas with an inadequate protective dune system, the dune may be 

breached or overtopped. If this occurs on a barrier island or spit, beach and 

dune sediments are carried landward and deposited on the backshore, in 

marshes, or in the bay. In severe instances, enough erosion occurs for a new 

inlet to be cut through the barrier. Inlet formation is most often caused, 

however, by trapped storm surge water creating a blowout from the bayside 

rather than erosion from the ocean side. Where low lying areas are protected 

by a dune system, a breach or overtopping may cause extensive flooding. In 

some areas with erodible formations such as sea cliffs behind the beach, loss 

35 
of bea~hsediment may result in wave action undermining the adjacent upland 

causing catastrophic landslides or rec.ession. Normal, long-term wave 

conditions may then rebuild a beach from. the new material or, conversely, 

transporl: the sediments out of the littoral cell. 

Long~term.beach stability and resistance to storm damages are related to 

the geologic andgeomor.phic features of the littoral cell. On the New England 

and Pacific coasts, resistant headlands may minimize storm wave attack, \Vhile 

on other coasts, offshore rocks and reefs and orientation of the shoreline may 

lessen the effects of storm waves. Many parts of the Great Lakes shoreline 

have a clay bed overlain by varying quantities of sands, cobbles, and 

boulders. Erosion. of the clay lakebed, when water levels are 10w3 , does 

little percept1bleeconomic damage but it sets the stage for damages when 

water levels rise. On sandy coasts, the supply of sand may be the major 

factor contributing to beach stability. A major interruption in the littoral 

cell sand transport, as at. a dredged: tidal inlet or a naturally-occurring 

littoral sink, may cause serious sbort-term er()sion which may lead to severe 

long-term storm damage. ,This vulnerability occurs if there is insufficient 

beach sand to rebuild the eroded bea.ch so it Can withstand storm attack. The 

severity of damage may vary along the shoreline depending upon the location 

and orientation of headlat)ds, inlets, structures or offshore features. 

FLOODING. 

Flooding is a common effect of coastal storms due to the superposition 

of tide, surge, wind, and waves, coupled with erosion of .the beach and dune~ 

3 Great Lake~ water levels fluctuate slowly·over a range of several feet 

with a time scale of several years. 

36 
It may occur along any section of low-lying coast. Coasts with barrier 

islands or beach/dune systems have some degree of protection from flooding. 

If storm damage or long~term erosion results in a breach of these natural 

protection features, more severe flooding can occur behind them. Inthis 

case,it is important to determine the height and width of protective dunes 

and.compare them to predicted storm elevations and expected erosion~ ·As with 

artificial dikes or levees, any breach in the protective dune can result in 

flooding the entire area behind. 

COASTAL ENGINEERING CONSIDERATIONS 

This section discusses the general approaches to predicting storm damage 

and long~term erosion. Storm erosion is primarily caused by waves and the 

high water levels associated with storms. Storm damage can be caused by any 

combination of wind, waves, water levels, and intense rainfall reSUlting in 

physical damage (other than caused by land loss) to structures and other 

facilities. The severity of storm erosion or damage is related to the length 

of time the higher energy waves occur in conjunction with elevated water 

levels. There are other factors which also influence the severity, including 

nearshore morphology, prior storm effects, and the presence or absence of 

erosion control structures, such as revetments or groins. Because of the 

complex nature of storm effects on the beach and the difficulty of collecting 

field data during storm events, there is no one standard storm damage or 

erosion analysis procedure. Rather, several storm erosion models are used 

throughout the Corps as the basis for evaluation. The approach used depends 

in large part upon the expertise of the coastal analyst and the availability 

:of data. The primary data required for storm damages relate to storm 

37 
conditions· and shoreline geometry. Long-term erosion requires historic data 

and information on littoral transport. In all cases, the frequency of extreme 

storm events needs to be determined. Technical Report CERC-87-l, "Sources of 

Coastaltngineering Information," is a useful reference guide. 4 

STORM CONDITIONS 

The most important storm conditions affectiIJ,g erosion or damage at a 

given location are ~ he.ight, Parioci, and direction, and the height and 

duration of storm surge. These variables (described below) are significant in 

ultimately describing .erosion and sto.rm damage frequencies. In riverine 

environments the discharge-elevation and discharge-frequency curves provide 

the basis for the elevation-frequency curve and ultimately the damagefrequency curve. In. coastal setting.s the storm-frequency curve and the 

relationship of storm surge and wave heights to shoreline erosion provide the 

basis for erosion-frequency and storm damage-frequency curves. 

Waves. Knowledge of incident wave conditions is essential for 

determining shoreline response. Wave conditions at the project site are 

frequently unknown and must be derived from either nearby measurements or from 

deepwater wave information. 5 Statistical analysis of available nearby wave 

climate data can provide mean wave height and period and direction of 

4. Coastal Engineering Research Center, Sources of Coastal Engineering 

Information, Technical Report CERC-87-l, (Vicksburg, MS: Waterways Experiment 

Station, 1987). 

5 The Wave Information Study (WIS), an,ongoing research effort performed 

by the Coastal Engineering Research Center, contains a database of hindcasted 

wave characteristics (height, period, and direction) for deepwater (ocean 

basin), continental shelf, and nearshore areas adjacent to all U.S. coasts. 

38 
deepwater waves approaching the shoreline. Nearshore wave height and 

direction can be measured directly or predicted from offshore data using a 

variety of numerical methods. Seasonal and long--term changes in wave climate 

are variable enough to require many years of data to determine the :fr.equency· 

of extreme waves. Hindcasting, sometimes calibrated by gauge data, is the 

technique most often used in frequency determination. .', 

The project wave conditions of interest include the height, direction, 

and period of the largest waves, the frequency of occurrence, and the 

duration. Extreme wave conditions associated with the sO:-or lOO~year storm 

are also' 'necessary and can be predicted from long-'term wind records as wave 

hindcasts. Deepwater wave statistics are available for most of the U.S. 

coast. These must be mathematically transformed to account for the shoaling 

and refraction ·effects of the offshore geometry and diffraction effects of'any 

offshore islands or structures. There are standard procedures available to do 

this, including computer programs such as the Automated Coastal Engineering 

System (ACES), Version 105, design and analysis system. 

Storm Surge. Storm surge is an increase in water level above the. normal 

astronomical tide due' to a combination of wind stres's,. wave setup, low 

barometric pressure, and offshore bathymetric contours. Wind stress is the 

vertical rise in the still-water level of a body of water due 'to the ',friction 

of winds blowing over the surface of the water. W'ave setup ,is the increase'!in 

water surface elevation at the shoreline due to onshore transport of water by 

wave action. An intense low atmospheric pressure condition may also 'cause the 

water surface levels to rise, while the offshore bathymetric profile impa~tS 

storm surge when a constant volume of water moving toward the. shore. is forced 

39 
upward by shallow or constricted bottom contours, raising the water surface 

elevation. 

The highest water levels during a storm occur when the storm surge 

combines with high tide, although the storm surge may persist through several 

tidal cycles. The normal tidal elevation is available from the predicted tide 

or actual measurements. Historic measurements, when available, are the best 

way to determine the extreme tide level and frequency of occurrence. However, 

if sufficient stage records are lacking, numerical analysis based on the joint 

probability of the random mixing of astronomical tides, northeasters, and 

hurricanes may be used to develop a stage-frequency curve. 6 In some cases, 

long-term water level change due to sea level rise, land subsidence, uplift, 

. or a combination, can be determined from long-term records. 

During most storms, low barometric pressure causes a rise in water level 

proportional to the magnitude of the low pressure. This may be a foot or more 

and can be estimated from historic water level records or calculated from 

empirical relations or numerical models. Storms also have high winds which 

can cause a rise in water level by forcing water towards the shore. This can 

usually be predicted using meteorological data. Wave setup increases the 

water surface elevation near the shoreline due to the effects of breaking 

waves. 

6 Observed tide levels normally only provide information on the magnitude 

of the more frequent events and are therefore used to calibrate the lower end 

of the stage-frequency curve. 

40 
DETERMINING EXTREME STORM EVENT FREQUENCY 

Hurricanes, tropical storms, northeasters or any recurring intense 

storms usually represent the most severe storm damage potential. These storms 

are usually associated with extremely large waves and/or high surge levels. 

Both wave height and surge level may be available from historic re~ords. More 

commonly, however, they will have to be estimated based on a combination of 

other records. The most common procedure is to use available hindc~st data to 

statistically derive the storm frequency relationship based upon s~ch 

parameters as maximum surge height, maximum storm still water level, or 

meteorological characteristics. When available, long-term water. level records 

can be used to develop an ocean stage-frequency relationship for water 

elevation and a surge-duration relationship. Both the height and duration of 

storm surge are necessary to characterize storm intensity. 

SHORELINE GEOMETRY 

The shoreline factors that most affect storm erosion are the size of 

sediments and the· shape of the beach profile. The slope of the beach is 

directly related to the grain size of beach sediments and, therefore, in most 

models of shoreline change, grain size is not required if slope data are 

available. The offshore slope and shape of contours affect incoming waves and 

cause variations in severity of erosion along the shoreline. Representative 

beach profile surveys may be available for the area extending from the depth 

of offshore transport (roughly the offshore bar) to the top of the existing 

dune. Because of the dynamic nature of the shoreline as shown in Figure 2, 

beach profiles need to be surveyed at different times of the year to reflect 

41 
different erosion conditions. These can be combined to give a representative 

profile for normal, pre-storm conditions. 

LONG-TERM, 'ERosIoN' 

", ! AS~tHment budget analysis for sources of beach material, pathways of ' 

transport, and deposition of eroded material is part of the assessment of 

short- or long-term erosion. The goal of the littoral analysis is to 

determine, the rate aod direction of ··1fttoraltransport· and quantify the effect 

of long-term erosion. Estimates'oferosion rates can be extracted from 

historical 'data such as aerial photo analysis,old maps, and surveys. One of 

the most widely used methods, employed'by many state coastal management 

programs requiring setbacks for new construction, is to extrapolate trends in 

shotelirte change from historical maps. Examination of historic data on 

dredging 'quantities may also be used in the development of the sediment budget 

for the area. The direction of transport is commonly inferred from historic 

changes in thesnoreline, especially where structures or tidal inlets occur •. 

The use of tidal inlet:behavior as an indicator of the prevalent direction of 

sediment transport must be used with'caution, however, as many inlets are.! 

known,to'niigrate opposite to the predominate transpart direction. Scour or 

fill 'at jetties orgroins,indicating direction of transport, can be seen on ( 

aerial photos . Dredging quantities at inlets may give' sonle estimate of rate 

of transport, although :the:materials dredged :from ocean bar 'channels'may be a:' 

combination (jfboth longshoresediment'transport and re-suspension of6cean 

bar matedalS'.' HiStoric bathymetric . comparisons and beach profile data ,may be 

used to es'timate .. gerieraT volumechariges. 

42 
A sediment budget attempts to balance sediment input and losses in the 

problem area. The result shows whether there should be a net long-term 

erosion or accretion. Longshore transport potential can be calculated from 

incident directional wave statistics; when properly applied and. combined with 

measured volume changes, these techniques provide reasonable and realis.tic 

estimates of longshore sediment transport. 

REIATIO~SHIP OF SHORELINE ANALYSIS TO NED BENEFITS EVALUATION 

Coastal engineering analysis obviously has a major role to play in the 

calculation of NED benefits. Most projects involve some recommended 

alternatives to alleviate one or more perceived problems. The determination 

of benefits is based on damages prevented or erosion c~:mtrolled w.ith the 

project, versus the without-project conditions. The damages are associated 

with a zone of impact caused by elevated storm tides, high waves, high winds, 

and shoreline recession that occur during a severe storm, exacerbated by the 

effects of long-term erosion. The objective is, therefore, development. of a 

set of relationships, using available data and models, to predict future 

various with- and without-project conditions. The shoreline responses, 

including the amount of erosion and related expected damages, would be based 

on the frequency of such parameters as storm surge elevations, storm duration, 

and wave heights. In some cases, multiple storm parameters have been combined 

to develop stage-frequency relationships for an area. For example, in the Sea 

Bright to Ocean Township, New Jersey beach erosion control project cited in 

Chapter IV of this manual, a range of erosion losses were developed which 

could be expected to occur for a given storm still water (stage) level. 

However, there is no one best relationship or model for all beach erosion 

43 
cases. In all cases, the study team will have to exercise professional 

judgement. Some of the models for quantifying and predicting shoreline change 

are described below. 

MODELS OF SHORELINE CHANGE 

HISTORICAL SHORELINE CHANGE METHOD 

The historical shoreline change method is based on an analysis of the 

long-term database of shoreline location, which must also take into account 

the effects of human interferences (e.g., beach nourishment, navigation' 

channels, dredging projects, seawalls, and groins). This analysis provides an 

average rate of shoreline evolution as well as a distribution of the 

fluctuations around the trend caused by seasonal variations .and episodic st~rm 

events. The existing database of shoreline locations is generally long-term 

and site specific. 

A wide variety of information on beach erosion exists for coastal and 

Great Lakes shorelines. The data, however, range from highly accurate 

engineering surveys to fairly general comparisons of historical photographs 

and maps at various scales. In addition to the Corps of Engineers, the 

National Oceanic and Atmospheric Administration (NOAA) and the u.S. Geological 

Survey (USGS) systematically collect coastal information. Further data are 

available from coastal states, local governments, universities, and private 

engineering and environmental consulting firms. Changes in shore position 

have been delineated using a wide range of methods, including field 

measurements of beach profiles, visual comparison of historic changes from 

44 
photographs,andquantitative .analysis of historical maps and vertical aerial 

phot()graphythrough various photogrammetric procedures. 

Extrapolation of trends based on historical shoreline change analysis 

must take into consideration the inherent variability in shoreline response 

based on differing coastal, processes, sSdimentary environments, and coastal 

exposures. Another factor is the time period of observation. The average 

rate of shoreline position change with respect to time may very likely differ 

for .. the same location for a lO-year versus a 20-year period because of, for 

example, the occurrence of extreme events (e.g., a hurricane) followed by a 

gradual beach rebuilding period'. In general, estimates of long-term erosion 

rates are more accurate " for longer periods of record and for higher trend 

rates. Furthermore,the straightforward projection of new shoreline positions 

based on historical change assumes that all oceanographic forces (e.g., waves, 

storm frequencies, sea level change) remain essentially constant. In summary, 

erosional trend rates can only be estliblished accurately in those areas where 

long-term shoreline positions are available or where trend rates are large. 

Where erosion rates are calcuLated to be in the low range (one foot or less 

per year), the reliability of this measurement is probably low due to natural 

fluctuations in the beach width. 7 

PREDICTIVE MODELS 

In recent.:years there has been substantial interest and much improvement 

in the development of calculation procedures, or models, for'. quantitative 

prediction of future shoreline changes. Such predictions are, obviously, a 

.l 1 

7 National Research Council, Managing Coastal Erosion, (Washington, DC: 

National Academy Press, 1990). 

45 
primaryinpue into the NED benefit analysis. As such, a brief overview of 

some recent modelling efforts is presented in the paragraphs below. It should 

be noted, however, that application and interpretation of these analytical and 

numerical mqdels does require substantial effort and skill. Technical advice 

on these predictive models can be obtained from the Coastal Engineering 

Research Center (CERC) at the Corps Waterways Experiment Station. 

Shoreline retreat can occur as a result of longshore sediment transp6rt, 

offshore sediment transport, or both. Offshore sediment transport is 

primarily responsible for shoreline retreat during storms, whereas long-term 

retreat can be caused by either, or by a combination, of these transport 

components. Individual models have tended to concentrate on shore response to 

longshore transport. Models are generally site specific for erosion and must 

be verified by the history of a particular site. 

Longshore models require two types of equations: 1) a transport 

equation relating the volumetric movement of sediment to the causative forces 

(e.g., waves and tides); and, 2) an equation that carries out the accounting 

of changes as a result of the sediment movement. Some of the earliest 

modeling efforts simplified the above equations for the case of longshore 

transport, thus allowing analytical solutions to be developed that provide 

considerable insight into the effects of individual parameters, such as wave 

height and direction. A report published by CERC8 summarizes a number of 

such solutions, including the effect of constructing a groin along the 

shoreline, the evolution of a beach nourishment project, and sediment changes 

8 M. Larson, H. Hanson, and N. Kraus, Analytical Solutions of the OneLine Model of Shoreline Change, Technical Report CERC-87-lS, (Vicksburg, MS: 

U.S. Army Engineer Waterways Experiment Station, Coastal Engineering Research 

Center, 1987). 

46 
from the transport of sediment to the coast by a river. In addition to 

analytical solutions, numerical solutions have been developed that allow 

specification of time-varying waves and tides. These models include the 

GENE.SIS model now used by the Corp.s. 

A primary objective in the development of cross-shore trans.port models 

is the estimation of a zone of impact caused by elevated storm tides and high 

waves occurring during a severe storm. Cross-shore transp.ort models are 

generally based on the concept that if the prevailing waves. and tides are of 

sufficient duration the profile will evolve to an equilibrium shape. The 

complexity of these models ranges from simple ones based on field and 

laboratory data to those that simulate profile evolution based on time-varying 

wave heights and storm surges as input. A report by the National Research 

Council, Manasins Coastal Erosion,7 provides a concise review of various 

cross-shore transport models, which are excerpted ~elow. 

An empirical model developed by Swart9 is based on large~scale wave 

tank tests. The procedure involves numer.ous empirical expressions that, when 

programmed, make the method relatively straightforward to apply. A profile 

response model based on a series of wave tank tests was also developed by 

Vellinga10 to evaluate the integrity of the Dutc? dikes against storms. The 

required parameters include wave height, storm tide, and grain size. The 

7 National Research Council, Managing Coastal Erosion, (Washington, DC: 

National Academy Press, 1990). 

9 D.H. Swart, "Predictive Equations Regarding Coastal Transports," in 

Proceedinss. Fifteenth International Conference on Coastal Engineering, (New 

York: ASCE, 1976), pp. 1113-1132. 

10 P. Vellinga, "Predictive Computational Modelling for Beach and Dune 

Erosion During Storm Surges," in Proceedinss of ASCE Specialty.~onfert=;nce 

Coastal Structures, (New York: ASCE, 1983), pp. 806-819. 

47 
method predicts the profile for a storm duration·of five hours; procedu.res are 

presented to evaluate storms of differing durations. 

A numerical model developed by Kriebel and Deanll allows time-varying 

input of storm tide and wave height and solves the equations governing crossshore sediment transport and continuity. The cross-shore sediment transport 

equation is based on the profile disequilibrium caused by elevated storm tide 

and wave height conditions. The model was evaluated against the sediment 

transport caused by Hurricane Eloise for Bay County, Florida. A simplified 

modification of this method is currently used by the Florida Department of 

Natural Resources in its implementation of the Coastal Construction Control 

Line program. 

An empirical method devised by Ba1si11ie12 models relationships for the 

average and maximum expected erosion caused by a storm based on storm tide 

rise time and peak storm tide. According to the National Research Council, 

Ba1si11ie's approach provides encouraging correlation with numerous field 

data. 

Finally, a model developed by Larson et a1. 13 was based on extensive 

correlations of wave, sediment, and profile characteristics. The beach. and 

nearshore profile is subdivided into four zones, each with different transport 

rate properties. The model has been applied to erosion of natural and 

11 D.L. Kriebel and R.G. Dean, "Numerical Simulation of Time-dependent 

Beach and Dune Erosion," Coastal Engineering, 1987, Vol. 9, pp. 221-245. 

12 J .H. Ba1si11ie, "Beach and Storm Erosion Due to Extreme Event Impact," 

Shore Beach, 1986, Vol. 54, No.4, pp. 22-36. 

13 M. Larson, N. Kraus, and T. Sunamura, "Beach Profile Change: 

Morphology, Transport Rate, and Numerical Simulation," in Proceedings. TwentyFirst International Conference on Coastal Engineering, (New York: ASCE, 

1988), pp. 1295-1309. 

48 
seawalled profiles. It is capable of predicting single and multiple bar 

formations. Comparisons and evaluations have been conducted with wave tank 

data, field data from Duck, North Carolina, and the Kriebel and Dean model. 

49 
CHAPTER. III 

DESCRIPTION OF PROJECTS AND BENEFITS 

AUTHORITIES 

There are a number of legislative authorities (both general and 

specific) under which the Corps provides coastal protection projects. 

Beginning with the River and Harbor Act of 1930, Congress has directed the 

Corps to carry out programs established to maintain the shorelines of the 

United States, including: 1) research to determine the causes of beach 

erosion; 2) investigations and studies of specific beach erosion problems; and 

3) construction of shore protection and beach restoration projects. The 

enactment of the Water Resources Development Act (WRDA) of 1986 established 

hurricane and storm damage reduction as project purposes. Among other 

changes, WRDA 1986 specified that beach erosion control costs be assigned to 

such "appropriate" project purposes as hurricane and storm damage reduction 

and recreation, with cost sharing in the same percentage as the purposes to 

which the costs were assigned. 

Individual coastal storm damage prevention or erosion control projects 

may be authorized by ~pecific Acts of Congress or granted under Sections 14, 

103, and 111 of the Continuing Authorities Program. Section 14 of PL 79-526 

authorizes emergency streambank and shoreline erosion protection for public' 

facilities and services, up to a maximum cost of $500,000 per project; Section 

103 of PL 87-874 authorizes Federal participation in the cost of beach erosion 

control for publicly owned property, up to a project maximum of $2 million; 

and Section 111 of PL 90-483 authorizes mitigation of shoreline erosion 

damages caused by Federal navigation projects, up to a maximum of $2 million 

51 
per mitigation project. See ER 1105-2-100, pages 3-1 - 3-23, for policies, 

procedures, and guidance affecting the Continuing Authorities Program. 

Appendix A discusses some of the most commonly used general authorities. 

OVERVIEW 

There are two major types of coastline protection projects in which the 

Corps is authorized to participate: coastal storm damage protection and longterm erosion protection. Coastal storms can cause damages from flooding, 

winds, wave impacts, salt spray, and sand and debris movement. In addition, 

storms can cause erosion of cliffs, bluffs, marshes, beaches, and dunes, which 

can lead to damages to protective structures, inland buildings, infrastructure 

and port and marina facilities. Long-term erosion generally occurs as a 

result of a deficit in the supply of littoral materials due to losses in 

natural or man-made sinks. Over time, the coastline retreats inland and 

unprotected land and improvements are washed away. 

TYPES OF PROJECTS 

Various options exist to reduce coastal storm damage and erosion hazards 

to public and private buildings and infrastructure. These options can be 

classified as shoreline engineering works or building and land use management 

techniques. Shoreline engineering includes both soft structural approaches 

(e.g., beach nourishment) and hard structural approaches (e.g., seawalls, 

revetments, groins, and offshore breakwaters). Building and land use 

management includes building and land use restrictions (e.g., setback 

requirements), and relocation of existing structures from eroding shores. 

Combinations of both engineering and management options are used on many 

52 
shorelines; however, engineering solutions tend to be employed on developed 

coasts, while the use of management solutions is encouraged on less developed 

coasts. 

SHORELINE ENGINEERING 

Beach Nourishment. Beach nourishment involves excavation from one site 

and placing large quantities of sand on an existing but retreating beach to 

advance the shoreline seaward. The material usually is placed on the beach at 

a slope steeper than the natural beach so there will be a period, of perhaps 

several years, during which profile equilibrium will occur. In addition, the 

extension of the shoreline will induce additional components of longshore 

sediment transport away from the original location. 

According to a report from the National Research Counci1,l the 

additional beach benefits from a beach nourishment project depend markedly on 

the quality of the sand placed. The same amount of material of varying sizes 

results in markedly differing equilibrated beach widths. Ideally, for 

greatest benefit, the sand should be as coarse or coarser than the native 

sand. However, current knowledge about sediment transport does not include 

adequate information concerning the influence of grain-size distribution. 

Many examples of both successful and unsuccessful beach nourishment 

projects exist. Successful projects include Miami Beach, Florida, where 14 

million cubic yards of sand were placed over a ten-mile beach during the 1976 

to 1981 period at a cost of $64 million. The first re-nourishment in 1987 

placed 300,000 cubic yards, which amounts to a loss rate of less than 0.3 

1 National Research Council, Managing Coastal Erosion, (Washington, DC: 

National Academy Press, 1990). 

53 
percent per year. The Indialantic Beach in Florida is regarded as an 

unsuccessful beach nou:rishment·project. Approximately 500,000 cubic yards of 

sand were placed along two miles of beach. One year after project 

construction, little volume remained within the portions of the profile 

encompassed by wading surveys. 

are structures bui).t perpendicular to the shore that may 

be constructed of timber, concrete, metal sheet piling, or rock (see Figure 

3). They may be built singly or in a series. Groins are intended to reduce 

longshore sediment transport; thus, when placed on an open coast, they widen 

the beach on the updrift side. Groins designed with heights that match the 

beach profile have less potential of causing downdrift beach erosion than a 

high profile and/or long structure that may divert water and sediment 

offshore. 

Groins have often been used improperly in the past, and some states have 

prohibited their construction. Groins used with care, however, have the 

potential to stabilize beach fills. A series of adjustable groins have been 

used in Deerfield Beach, Florida, whose upper elevations may be maintained 

slightly above the sand level. In this way, the structures can be adjusted to 

ensure that they function primarily to stabilize material in place rather than 

trap material in transport. A field of groins or groins placed as terminal 

structures might be particularly appropriate to retain material placed in a 

beach nourishment project. Additionally, a field of groins or a single, long 

terminal structure may be suitable near the end of a littoral cell, such as 

adjacent to a channel entrance. 

Seawalls. Bulkheads. and Revetments. Properly engineered seawalls, 

bulkheads, and revetments protect the land behind from erosion and wave 

54 
..... 

Figure 3. Rubble-mound Groins. 

attack. The differences between these protective, wall-like structures are 

mainly matters of purpose and scale. Seawalls normally are the most massive 

and defend against the full force of waves. Bulkheads are generally the next 

largest and are designed to retain fill and resist erosion. Revetments are 

usually the lightest because they are designed to protect shorelines again~t 

erosion by currents or light wave action. While these structures are built on 

eroding shorelines, they are often blamed for additional erosion that occurs. 

This may happen if they are not designed and constructed properly, which can 

cause adverse impacts on adjacent property. The only principle that is 

definitely established is the one of "sediment conservation." Coastal 

55 
armoring (e.g., a seawall or revetment) neither adds to nor removes sand from 

the sediment system but may be responsible for the redistribution of sand and 

can prevent sand from entering the system. Additionally, seawalls, bulkheads, 

and revetments are expensive and require proper maintenance. 

Offshore Breakwaters. Offshore or detached breakwaters are typically 

constructed from rock or concrete .armor units and protect the shoreline by 

reducing wave energy reaching it (see Figure 4). They also promote sediment 

deposition leeward of the structures. Most offshore breakwaters built for 

shore protection are segmented and detached; thus, they provide substantial 

protection to the shoreline without completely stopping longshore sand 

transport. They do not deflect and relocate currents, like breakwaters or 

jetties that project from the land. Unlike seawalls, revetments, and 

bulkheads, breakwaters aid in beach retention because they reduce wave energy. 

A main disadvantage is that they are more expensive to build than land-based 

structures. 

Submerged breakwaters, also known as artificial reefs, may be composed 

of sunken barges or ships or any heavy objects that break up wave action. 

They can cost much less than breakwaters that project above the water surface 

because they do not have to absorb the full wave impact, but merely cause 

storm waves to break and spill their energy in turbulence. 

Jetties are engineering structures built at the mouths of rivers or 

tidal"inlets to help deepen or stabilize a channel. While they are thus 

similar in appearance to groins or breakwaters attached to the shore, their 

purpose is not necessarily to protect the shoreline, but rather to prevent 

shoaling of a channel by littoral materials and to direct and confine stream 

or tidal flow. 

56 
Figure 4. Detached Breakwater. 

Sand Bypassing. Inlets, navigation channels, and harbor entrances all 

interrupt the natural flow of sediment transport along the shoreline. The 

interrupted flow of sand is diverted either offshore in ebb tide shoals, into 

bays or lagoons in flood tide shoals, or in navigation channels. They 

generally cause shoaling and downdrift migration of channels, which require 

frequent dredging in order to maintain safe navigation. As a result, erosion 

occurs downdrift of the interrupted coastline. Sand bypassing, by either a. 

fixed or floating pumping system, restores the natural flow of sand to the 

downdrift shorelines and reduces the need for channel dredging. In Florida, 

the use of two fixed bypassing plants for a period of 30 years suggests the 

57 
feasibility of such systems to alleviate human-induced erosion downdrift from 

inlet control structures. Floating dredge (temporary) bypass operations also 

have been used in the United States. One example is a Federal project at 

Channel Islands Harbor, CA, where over one million cubic yards of sand is 

bypassed on a biennial basis past two harbor entrances to restore eroding 

downdrift beaches. 

Dune Building. Natural sand dunes are formed by winds blowing onshore 

over the beach, transporting sand landward. Grasses and sometimes bushes grow 

on sand dunes, creating a natural barrier against sea attack. The dunes 

provide a reservoir of beach sand during severe storms and thus help prevent 

flood and wave damage to adjacent property. In areas where substantial dunes 

exist, the post-storm beach width can be greater than the pre-storm width. 

Attempts have been made to imitate nature by promoting the formation of 

artificial dunes. States where large-scale dune construction has been 

implemented include North Carolina, Texas, Florida, New Jersey, and Maryland. 

BUILDING AND LAND USE MANAGEMENT 

Since the advent of the National Flood Insurance Program (NFIP) in 1968, 

legal and institutional ("nonstructural") measures have become importaht 

mechanisms used to reduce the vulnerability of coastal and riverine structures 

to flood and erosion losses. Planners have often seen engineered responses to 

coastal erosion as unsuitable from an economic and environmental perspective, 

especially when used to protect privately-owned, lower density residential 

development. One approach to coasta'l management is to influence the location, 

elevation, and design of new or substantially redeveloped structures through 

public building and land use controls. 

58 
The NFIP, in particular, has fostered the adoption of floodplain 

management standards by some 1200 coastal communities nationally. Like their 

counterparts along inlan~ floodplains, these communities must require minimum 

elevation of new structures above estimated IOO-year flood ("base flood") 

levels that include the effect of wave heights. These land development 

restrictions generally have been held to be constitutional. 

Setback Requirements. Coastal construction standards ul1der the NFIP 

have emphasized elevation rather than horizontal displacement. New buildings, 

on substantial pilings up to 20 feet above grade, are a familiar site in 

recently built communities along the Atlantic and Gulf coasts. But horizontal 

displacement is required under the NFIP's minimum standards, only to the 

extent that new buildings in high hazard zones (V-zones) must be located 

landward of the reach of mean high tide and must not alter dunes or mangrove 

stands (44 Code of Federal Regulations Section 60.3(e». Even these 

requirements do not apply to coastal A-zones (e.g., bayside or other non-open 

ocean shorelines). 

A number of coastal states have established horizontal setbacks for new 

construction at the individual state level. According to NOAA, there are 

three basic approaches states have taken: 1) natural resource prote<:tion 

statutes; 2) fixed setback lines; and, 3) average annual recession rate 

setbacks. The first category includes states, such as Massachusetts and 

Wisconsin, that place limitations upon development in wetlands or on dune 

systems. These requirements are not specifically designed to address erosio.n. 

Fixed setback lines involve a minimum specified distance (e.g., 100 feet 

in Delaware) from a reference feature. Types of physical reference features 

include the seaward toe of primary dunes, line of vegetation, edge of eroding 

59 
bluff, mean high water, or a specified elevation contour. These features may 

move whenever erosion occurs. 

Several states use "average annual erosion rate" setbacks to mark the 

minimum setback.for new construction. Michigan and North Carolina impose a 

30-year setback on smaller structures; North Carolina also imposes a 60-year 

setback on larger ones. 

Relocation. According to the National Research Council,2 relocation of 

existing structures from eroding and/o; flood-prone shorelines has long been a 

neglected mechanism for responding to shoreline retreat. The technical 

feasibility of moving small or medium-sized structures has been established. 

Relocation as a widespread adjustment to shore erosion is most likely to be 

cost effective for smaller s.tructures, particularly one and two-story 

residential structures. Relocation encounters a number of institutional and 

economic impediments. Structures on deep lots may gain sufficient protection 

by relocating landward on the same lot. However, if sufficient space is not 

available on the same lot, a~ alternative site must be acquired and prepared. 

This increases the cost of relocat~on substantially. It may also incur 

problems of zoning; mortgage refinancing; and provision of sewer, water, and 

road access. The alternative site may lack the view and/or direct shoreline 

access that are often the reason for waterfront property ownership. 

However, a .. structure threatened by imminent collapse essentially is 

valueless and poses substantial potential costs to the community in terms of 

lost tax revenue, det.erioration related to abandonment, clearance of wreckage, 

casualty loss deductions from income tax liability, disaster relief payments, 

2 See Footnote 1, page 53. 

60 
and flood insurance loss payments. Relocation, therefore, may be a desirable 

public goal. 

Construction Reguirements. Damage to structures located along the 

shore, in some cases, can be reduced by relatively straightforward engineering 

and construction procedures to ensure the building's survivability during a 

severe storm event (e.g., the 100-year storm even~). Such requirements would 

include elevating the lower horizontal structural members above the 100-year 

wave crest elevation; embedding pilings on low dunes to an adequate depth to 

ensure structural integrity during a 100-year storm tide and associated 

erosional event; and reinforcing connections between structural members to 

withstand anticipated 100-year wind loading. A1thougp these construction 

guidelines would be required for new structures, retrofitting of existing 

structures may also be economically feasible. 

Land Acguisition. A land acquisition program is another strategy to 

cope with coastal erosion and storm damage management. This .is appropriate 

where erosion- or damage-prone areas can be acquired by government units and 

preserved for recreation, open space, or other appropriate public purposes. 

Such programs generally include specific criteria and priorities for 

acquisition, ident,ify funding sources, and set timetables for action. 

Potential Federal funding sources include Section 1362 of the National Flood 

Insurance Act, the Land and Water Conservation Fund, and Section 306A of the 

Federal Coastal Zone Management Act. The community plans also can identify 

state and local resources that will be devoted to this program. 

61 
BENEFIT CATEGORIES 

Since a project may protect against both storm damage and erosion, it is 

necessary to be able to evaluate the benefits of both types of protection, and 

to avoid double counting of benefits for all coastal protection projects. The 

remainder of this chapter discusses the potential benefit categories for storm 

damage prevention: and erosion protection. 

STORK DAMAGE ALLEVIATION BENEFIT CATEGORIES 

~ave Damage Reduction Benefits. In many areas, damages caused by wave 

action can be the most significant coastal effect. The force of tons of water 

against beach front structures can be more destructive than the damage caused 

by erosion .. This category of damage can also be the most tedious to 

determine, especially when damages are calculated on a structure-by-structure 

basis. Alternatively, a structural engineer familiar with the area may 

develop a matrix showing the percentage of the value of a particular structure 

type damaged by waves of a given magnitude. 

Inundation Reduction Benefits. Many benefits from storm damage 

alleviation projects come from the reduction of inundation damages from 

coastal flooding. Inundation reduction benefits include reduction of both 

physical and non-physical costs. These benefits include the saving of 

structures and contents from flood and salt water damage, and the alleviation 

of clean-up costs, production losses, flood fighting expenses, evacuation 

costs, emergency aid, and traffic rerouting. In agricultural areas, potential 

benefits from inundation reduction also include the reduction of damages to 

crops such as inundation damages and saline effects on the soil. Inundation 

62 
reduction benefits result from alleviation of a combination of the following 

physical and non-physical damages. 

Physical Damage. 

1. Urban Losses. On urbanh:ed coasts and suburban beach communities, 

physical damages include structural damages to buildings; loss of .contents of 

the buildings, including furnishings, equipment, decorations, raw materials, 

and processed material; and damage to streets, highways, railways, sewers, 

bridges, utility lines, bulkheads,· seawalls, boardwalks, piers, port and 

marina facilities and other infrastructure·. Physical damages are evaluated 

s~parately for residential, commercial, industrial, and public properties; and 

for transportation systems, utilities, and vehicles. Although inundation 

reduction dam~es are similar to those calculated for riverine flood damages, 

factors such as seasonality, wind effects, undermining potential and salt 

water effects must be taken into account. 

2. Agricultural Losses. For flooding in agricultural areas, damages are 

separated into crop and non-crop losses. Crop losses are determined by 

calculating the net income lost as a result of flooding. Losses may result 

from increased production costs and/or decreased crop yields which could last 

for several years if salt water permeates the soil. Non-crop losses are 

calculated for other agricultural properties, associated agricultural 

enterprises, and off-site sediment damages. 

Other agricultural properties include farm buildings, stored crops, 

movable machinery and vehicles, fixed equipment, fences, roads and railroads, 

drainage and irrigation ditches, livestock, pasture, seeds, pesticides, 

herbicides, and fertilizers. The procedures for the calculation of damage to 

buildings and roads are similar to the procedures for urban projects. 

63 
However, estimation procedures for other agricultural properties are unique 

and require specialized knowledge of inventory procedures, damage 

susceptibility and storm characteristics. More detailed information on the 

unique considerations important to the evaluation of non-crop farm losses is 

presented in Chapter VI of the NED Procedures Manual - Agricultural Flood 

Damage. 

Off-site sediment reduction benefits are based on the costs of removing 

sediment from facilities such as roads, culverts, and channels. The increased 

cost of providing goods and services (such as additional treatment costs for 

removing sediment or other contaminants from municipal water) are also a 

component of potential damage. 

The calculation of inundation reduction benefits is discussed in the 

Urban Flood Damage and Agricultural Flood Damage NED Procedures Manuals. For 

coastal storm damages, inundation damage curves must be adjusted to account 

for wave runup, salt water, and damages from sand, debris and ice. For 

example, an inundation event characterized by heavy sediment load (suspended 

sand and/or debris) is particularly damaging to the workings of mechanical 

equipment and drainage systems and creates cleanup problems. Likewise, salt 

water's corrosive effects will have greater impact on metal structures or 

equipment. Even though most damage assessment procedures focus on the depthdamage relationship, the incorporation of factors like sediment load or saline 

content may be accomplished by "add on" percentage factors. For example, 

estimates of total residential damages for a given area may need to be 

increased by a factor of ten percent to account for the corrosive effects of 

salt water. Such data may be obtained from historical information on damages 

or individual case studies. More detail on these procedures is provided in 

64 
Chapter IV of this manual. Estimation of damages due to wave attack must 

always be evaluated on an individual site basis, and requires knowledge or 

assumptions of wave regimes. 

Non-Physical Damage. 

1. Income Loss. Income loss is the loss of wages or net profits to 

businesses over and above physical storm damages. It results from a 

disruption of normal activities that cannot be recouped by other businesses or 

from the same business at another time. Prevention of income loss can be 

counted as a national benefit only to the extent that such loss cannot be 

offset by postponement of an activity or transfer of the activity to other 

establishments. Agricultural crop and aquaculture losses generally result in 

income losses. Most business activities, except those which are unique to a 

given area, or which exert a major impact on the total output of a given 

product or industry are -considered transferable to another area. Usually, 

tourism is not considered unique to an area, even though a given location may 

have sights not available anywhere else, because vacationers can and often 

will visit another location. To the extent the transferred business actually 

results in higher costs, there is a loss identified with the effect of storm 

damages. Higher costs can be the result of greater distances or the required 

use of less efficient facilities, resulting in higher unit costs. Even 

vacationers may be required to incur greater travel cost and/or out-of-pocket 

expenses for leisure time alternatives. 

2. Emergency Costs. Emergency costs include both those expenses that 

result from the risk of a storm and those expenses that result from the storm 

itself. Emergency costs include expenses for monitoring and forecastihg storm 

problems, emergency evacuation, storm fighting efforts such as sandbagging and 

65 
building closures, adm;nistrative costs of disaster relief (but not the relief 

itself, which is a transfer), public clean-up costs, and increased costs of 

police, fire and military patrol. Emergency costs should be determined by 

specific surveyor research and should not be estimated by application of 

arbitrary percentages of physical damage estimates. 

3. Te~porary Evacuation. Temporary evacuation costs inc1ud~ temporary 

lodging .and the additional costs of food, clothing and transportation offered 

to relieve the financial hardship experienced by storm victims during and 

immediately after a storm emergency. Often, temporary evacuation costs are 

included in emergency costs. If the victims of storm damage have insurance 

coverage, however ,.to help defray temporary evacuation and relocation costs, 

reductions in these costs .attributed to the storm damage alleviation project 

cannot be counted as benefits since insurance payments are transfers. 

4. Temporary Relocation. Temporary relocation includes the additional 

living expenses incurred by storm area residents who are forced to find 

temporary housing after a storm event. Homes may be made uninhabitable due 

to: 1) extended periods of inundation; 2) structural damage that is too 

severe to live with; 3) large deposits of sand and debri~; and, 4) 

disruption of utility services and transportation routes. In general, 

temporary relocation lasts longer than temporary evacuation. Care must. be 

taken to only include permanent residents (or seasonal residents when. the 

damages occur during periods tho~e people would normally reside in the area) 

in the temporary relocation. benefits. 

5. Transportation Delay Costs. Flooding can temporarily impede traffic 

by coverin& or destroying roads and bridges. Even the .threat of flooding and 

concern for .public safety may make it necessary to close roads and detour 

66 
traffic. Only those delays and road closures that could actually be avoided 

by the proposed project may be counted, as the presence of the damaging storms 

with or without a project may be sufficient to precipitate road closure or 

delays. Bridge and road damage may cause detours for several months until 

repairs can be made. 

6. Damages to Associated Agricultural Enterprises - Associated 

agricultural enterprises are defined in P&G as economic activities that may be 

affected by changed water supply or water management conditions. An example 

of this type of damage is delay in spring planting on non-flooded lands 

because of flooding or severing of access roads. 

7. Reduced maintenance of existing structures. Structures in the 

immediate vicinity of the shore may require more frequent maintenance because 

of ocean spray or frequent wave attack. Benefits can be claimed to the extent 

that a project would reduce the extra maintenance. 

8. Other Costs of Occupying the Storm Inundation Area. Other stor~ 

inundation area occupancy costs include: 1) erosion protection/storm-proofing 

costs incurred in construction of new development; 2) the administrative 

costs of flood insurance; and, 3) modifying the use of storm inundation area 

property because of the flood threat. 

Other Benefits. While inundation reduction benefits constitute a large 

portion of economic justification for storm damage projects, they do not 

measure the total economic gain for storm damage loss reduction. Location and 

intensification benefits represent increases in economic welfare because 

reduction in storm damage risk allows for higher economic use of the property. 

The following benefit categories are similar to urban flood control, and are 

described in more detail in the Urban Flood Damage manual: location benefits, 

67 
efficiency benefits, employment benefits, advanced bridge replacement 

benefits, and affluence benefits. 

EROSION PROTECTION BENEFIT CATEGORIES 

Measures for control or prevention of beach erosion may include tangible 

primary benefits from physical damages prevented, emergency and business costs 

avoided, enhancement of property values, improvement of fish and wildlife 

resources, and increased recreational usage. Benefits should be measured as 

the difference in these values under conditions expected with and without the 

proposed erosion control measures. 

Damages due to shore erosion include physical losses of land and beaeh, 

and associated damages to improvements such as roads, buildings and other 

facilities. The loss of protective structures or an increasing threat of 

storm damage may cause owners to defer maintenance of existing structures or 

construction of new (replacement) facilities with resulting depression of 

economic values. 

Loss of Land. The area of land that would be lost in the absence of the 

project over the period of evaluation may be estimated on the basis of the 

historical rate of shore erosion in cases of long-term erosion. In instances 

of erosion due to coastal storms, the area that would be lost may be estimated 

with coastal erosion models which predict rates of erosion for storms of 

various frequencies. Other factors which may tend to modify the rate of the 

loss, such as construction of other coastal works which would change the 

supply of beach material to the problem area, must be taken into account. 

Structural Damage Prevention. Structures are often more severely 

damaged by erosion of the land under them in coastal storms than in riverine 

68 
flooding situations. Actions taken as a result of this erosion-induced damage 

can include relocation of the remaining structures (if damage is not severe) 

or abandonment of the property. State or local coastal zoning ordinances may 

determine if an activity can be re-established in the same location. 

Emergency Costs. Emergency costs for erosion protection benefits are 

similar to inundation reduction benefits. If benefits are claimed for both 

inundation reduction and erosion protection, care must be exercised to 

separate emergency costs which can be prevented by each category from those 

which will be realized only if both types of damage are prevented. 

Reduced Maintenance Of Existing Structures. Structures in. the immediate 

vicinity of the shore may require more frequent maintenance because of 

recurring inc.idents of erosion. Benefits can be claimed to the extent that a 

project would reduce the extra maintenance. 

Incidental Benefits. Projects for the primary purpose of beach erosion 

control often result in incidental benefits to other purposes. These 

benefits, such as increased beach and shoreline recreational activities,3 

increased fish and wildlife habitat, reduction in shoaling at navigation 

projects, reduction in tidal flood damages, and incidental benefits to private 

property downdrift of a shore protection project, should be evaluated and 

credited to the beach erosion control project. While the level of effort and 

detail dedicated to these benefits are usually minor in comparison to other 

benefit categories, they should not be overlooked. For example, in some 

studies, downdrift effects can be substantial and need to be thoroughly 

investigated. 

3 Methods of evaluating recreation benefits are illustrated in IWR Report 

86-R-4, National Economic Development Procedures Manual - Recreation. 

69 
Enhancement bf Property Values. Location and intensification benefits 

attributable to an erosion control project result from increased use of land 

through either intensified activities or by changing to an economically 

higher-valued development than would occur in the absence of the project. 

Such benefits result because of the higher utilization made feasible by 

increased safety of investments in improvements. Land enhancement benefits 

are oVer and above benefits received from damage reduction. 

Land already developed for its highest potential usage is assumed not to 

increase in real value. However, lands on which structures are being 

permitted to deteriorate, or on which development has been precluded simply 

because of vulnerability to damage arising from beach erosion, are subject to 

a change to a higher usage with attendant increase in value as a result of 

protection. A realistic appraisal should be made of the immediate project 

area and adjacent zones to determine which lands have been retarded from their 

highest potential utilization because of the prospect of erosion damage. 

Location benefits should be evaluated only for lands which have a 

reasonable prospect of change in usage, whereas intensification benefits 

should be evaluated only for lands which have a reasonable prospect of 

remaining in the same land use but with intensified activity. Location and 

intensification benefits apply only to land values and not to the value of 

future improvements. 

If a project is expected to produce location or intensification 

benefits, separate damage calculations must be made for the without-project 

and the with-project conditions. The without-project calculations would then 

include all damages to property (including those expected to be displaced with 

a project) if no Federal action is undertaken, while the with-project 

70 
calculations would encompass damages to activities which would be in place 

with the project. The intensification/location benefits must be net of 

induced or residual damages to the increased development. 

SYSTEMS ANALYSIS AND DOWNDRIFT IMPACTS 

The term "Systems Analysis" is 1,.lsed to refer to an evaluation that takes 

into account the broad range of possible impacts induced by a Corps project on 

a region outside of the specific project area. In the case of coastal 

projects, a reduction or an increase in damages to neighboring properties or 

downdrift areas may result from the design and implementation of storm damage 

protection and navigation structures, and should be accounted for in the 

project analysis. 

Regional "downdrift impacts" may be. manifest in different ways. The use 

of beach nourishment as one alternative .means of providing storm damage 

reduction may result in direct shore protection benefits downdrift of the 

specific project area. On the other hand, induced storm damages can result 

from the construction of a levee or seawall, which can cause an increase in 

interior ponding. A jetty built to prevent shoaling of a navigation inlet may 

disrupt littoral transport, and deplete a beach downdrift.. Conversely, a sand 

by-pass operation designed to reduce shoaling of the entrance channel will 

also improve a downdrift beach. If dredging operations in a navigation 

channel result in depositing the material in deep water or upland, erosion may 

increase downdrift of the area, whereas using the material to replenish the 

downdrift beaches may improve littoral transport for many miles downdrift. 

Controlling erosion in one area may affect littoral transport and cause 

71 
increased erosion in a downdrift area which is dependent upon sand 

replenishment from the project site. 

Guidance for the analysis of downdrift shore protection benefits and 

costs induced by Corps projects is provided in EC 1105-2-191. According to 

the EC, "A systematic view is necessary for measuring these benefits and 

costs, and for deciding which combination of shoreline protection measures and 

navigation features are appropriate for a given region." The guidance 

requires that the documentation of the downdrift shore protection benefits and 

costs be based on a traditional approach in describing existing "with" and 

"without" project improvement conditions. However, the analysis should extend 

beyond the project site to provide a more comprehensive view of the shore 

including adjacent reaches bounded by natural features (e.g., bays, sounds, 

inlets, geomorphic features) that serve to substantially interrupt or limit 

the continuity of natural longshore littoral processes. 

A systems analysis approach as explained in EC 1105-2-191 should 

describe: 1) the physical processes, including development of sediment 

budgets, estimates of the effects and probability of occurrence of relevant 

storm events, and assessments of the magnitude of average annual changes in 

beach area and volume; 2) the existing "without-project" coastal alterations, 

involving the identification of man-made alterations to the shore and their 

contribution to the balance of littoral processes and shoreline changes; 3) 

anticipated shoreline changes, including estimates of future shore nourishment 

and dredging activities; and, 4) the economic benefits and costs of 

alternative protection projects, including assessments of the extent of 

damageable property through storm surge and wave damage, estimates of damage 

reduction benefits for various project alternatives, and evaluations of all 

72 
beneficial and adverse impacts for each project alternative in accordance with 

P~. 

In short, all effects must be measured, whether in the immediate project 

area or not. Therefore, it is imperative that updrift and downdrift areas be 

considered as part of the study area, and evaluated accordingly. After the 

coastal engineer has helped identify the magnitude and location of physical 

changes both updrift and downdrift, economic evaluation techniques employed 

for those areas are the same as those used for the immediate study area. 

73 
CHAPTER IV 

ESTIMATING NED BENEFITS 

This chapter describes the steps involved in conducting the NED benefit 

analysis. It is described here as an eleven-step process, which should 

proceed in more or less the specified sequence in order to maximize efficiency 

and minimize duplication of effort. Variation in the progression of steps is, 

of course, acceptable, and some iteration will be inevitable. However, some 

steps cannot be accomplished without the preceding steps already being at 

least partially completed, while others may be started but not fully concluded 

without input from the prior steps. 

To more fully describe the NED benefit estimation process, examples from 

a recently completed coastal storm damage prevention and beach erosion control 

study conducted for the New Jersey coast1 are interwoven into the following 

discussion. The example information is included solely for illustrative 

purposes. Furthermore, only portions of the study are used to highlight 

certain benefit estimation procedures. It is, however, based on an actual NED 

benefit analysis, and, as such, may serve as a useful reference for planners 

and economists. The reader may note that the New Jersey study did not 

identically follow the sequence of benefit estimation steps suggested in this 

manual. This discrepancy is perfectly acceptable. As suggested in Chapter I 

1 The example information is extracted from: "Appendix D - Benefits," in 

Atlantic Coast of New Jersey. Sandy Hook to Barnegat Inlet Beach Erosion 

Control Project Section I - Sea Bright to Ocean Township. New Jersey. 

Technical Appendices. Volume II. General Design Memorandum, U.S. Army Engineer 

District New York, January, 1989. This document is reproduced as "Appendix B, 

An Example of NED Economic Benefits Analysis" in this manual for those readers 

desiring greater detail. 

75 
of this manual, analysts involved in the evaluation of coastal storm damage 

preventi~n and erosion control projects have considerable latitude in 

adjusting procedures to meet the needs or attributes of their particular 

study. 

STEP ONE: D.ELINEATE THE STUDY AREA,2 

The study area is that area which is immediately or indirectly affected 

by the perceived problem3 , and ,thus by any resulting project. This is the 

geographic region that includes the storm inundation area, as well as the area 

that will be affected by erosion, including downdrift, over the project 

evaluation period. It also includes an area sufficiently inland to describe 

the impacts of the storm erosion events and any protective measures. For 

example, utility lines anQ. roaQ.,s along, the beach may serve homes or businesses 

some distance inland, and severing of these would cause service disruptions to 

a wide area. The study area should encompass natural features that serve to 

substantially interrupt or limit the continuity of natural longshore littoral 

processes (e.g., bays, sounds; inlets, and the end of geomorphic features). 

Depending on the particular study, it may also include the nearshore areas for 

determination of comparable land,values or for consideration of alternative 

development sites and/or the market area for recreation users. Figure 5 is a 

2 The study area can also be defined and restricted by specific 

authorizing legislation. 

3 The first two steps frequently require many iterations. It is usually 

difficult to determine the study area without a definition of the problem, but 

it is just as difficult to fully define the problem without at least a partial 

definition of the study area. In many cases this effort may be facilitated by 

a coastal engineer's "desktop" assessment of geomorphic processes and trends, 

which can serve as a background for the other disciplines to use in their 

analysis. 

76 
graphic representation of some of the areal concepts discussed in Steps One 

through Three. 

After identification and mapping of the study area, the next part of the 

process is for the study team to delineate the affected area for detailed 

hydraulic and economic evaluation. Factors that should be identified include 

the length of shoreline, types of structures and economic activities, height 

and width of dunes, beach slope, beach material gra~n size, offshore slope and 

depth to bars, presence of tidal inle~s, presence of barrier islands or 

offshore reefs, and any protective measures already in place. The affected 

area consists of the area impacted by st9rm damage or erosion, including 

downdrift, plus all other areas likely to serve as alternative sites for any 

activity which might use the affected area if. it were protected. (The analyst 

should be satisfied that sufficient detail is included to provide an accurate 

analysis, but need not go into an exhaustive analysis.) This can be done by 

observation and notation of existing land use, public meetings, review of 

local land use plans, and consultation with planners and other local 

officials, business leaders, and citizens' groups. It is important for the 

entire study team to be involved ~n this proces~ because the assumptions made 

in delineation of the study a~ea ~ay have significant impacts on subsequent 

steps of the study process. For example, employing beach replenishment as an 

alternative to protect structures in the study area may have economic 

ramifications downdrift by increasing the costs of dredging a navigation 

channel. 

77 
"'" .... 

"' .... ... 

,," I State 

I 

/ Park 

I 

I 

I 

I 

I 

I 

\ 

I 

1 

Entire map is the study area. 

P lann ing 

Reach 

\ 

I . ~ lann Ing 

Reach , 

P lann ing 

Reach 

~ 

Rock 

Rock 

P lann ing 

ReaCh y 

...... _-

Littoral 

Cell 

Ocean 

Littoral 

Cell 

Shoreline 

Figure 5. Planning Reaches and Littoral Cells. 

78 
EXAMPLE 

In the New Jersey study, the study area is bounded by the natural 

features of Sandy Hook to the north and the outlet of Deal Lake to the south. 

It includes the most northerly 12 miles of the larger authorized project, 

Atlantic Coast of New Jersey. Sandy Hook to Barnegat Inlet Beach Erosion 

Control Project. The northern potion of the study area, including the towns 

of Sea Bright and the northern part of Monmouth Beach, is comprised of a 

barrier spit complex where the shoreline is a parrow strip of unconsolidated 

sand which forms a peninsula between the ocean and bay environments. The 

southern portion of the study area, encompassing the southern part of Monmouth 

Beach and the communities of Long Branch, Deal, Allenhurst, and Loch Arbour, 

is located on the coastal plain and is characterized by headlands meeting the 

sea. The entire study area is within Monmouth County. Immediately to the 

north of the project limit is the Sandy Hook unit of Gateway National 

Recreation Area, while immediately to the south is the City of Asbury Park. 

The entire coastal zone within the study area is heavily developed, 

primarily for residential and commercial uses. Many of the residences are 

former summer homes converted for year-round use. In areas with substantial 

existing beach, high rise and townhouse development has occurred. The 

peninsula area is fronted by a seawall up to 20 feet in height which aids in 

the prevention of flooding and wave attack. Traversing the peninsula area is 

State Road 36 which provides the only access to Sea Bright and Sandy Hook. 

STEP TWO: DEFINE THE PROBLEM 

The existing storm damage and erosion problems should be carefully 

defined. Care must be exercised to separate problems from symptoms; if the 

79 
problem should need to be redefined later in the study, it may be necessary to 

also redefine the without-project condition, and revise much of the rest of 

the analysis. Records should be consulted for instances when damaging storms 

have occurred in the area; the area and vertical extent of inundation and 

storm or wave attack should be determined; and hydrologists, coastal 

scientists, and engineers should gather information, for the period of record, 

on storms and erosion trends. Even though careful attention is paid to 

determination of the problem in this stage, the study team should be cognizant 

of the possibility that, as the study progresses, new information may reveal 

different causes of the symptoms. 

The existing without-project condition must be properly identified since 

it is the basis for comparison with conditions projected with all alternative 

plans. Existing and anticipated without-project man-made alterations to the 

shore, such as seawalls, groins, sand-bypassing and recycling, dredging, 

breakwaters, and artificial beach nourishment should be taken into account. 

An evaluation should be made of the effectiveness of any existing shore 

protection measures, and all other relevant non-structural measures (e.g., 

flood warning systems) existing or expected to be implemented before 

construction. 

The description of the existing conditions should include a history of 

the economic and social effects of storm damage and erosion problems in the 

area. Dates, storm intensities, wave heights, shoreline erosion, sediment 

movements, and peak stages of major storm events should be gathered. When the 

information is available, the economic costs and categories of damages, as 

well as the number of deaths and injuries, should be noted. Information on 

major events can be obtained from the National Weather Service, Corps 

80 
emergency operations offices, and state and local emergency preparedness 

offices. Local and regional newspapers may be a source for documenting 

historical storm losses. Shoreline changes can be determined from aerial 

photos and maps. Sometimes historical site photos are helpful in determining 

structural damages. In developed areas, site survey data may be available 

with beach and dune positions and elevations. 

A critical part of defining the existing without-project condition is a 

proper evaluation of the degree of protection that existing facilities can be 

expected to provide. The assessment involves two major considerations. The 

first consideration is the level of protection that existing storm and/or 

erosion control works actually provide. For example, if a seawall already 

exists, design engineers should determine how well it actually reduces 

overtopping and the conditions under which it would fail. Second, the 

protection offered by any structure is dependent on its own structural 

integrity. A project can only be considered effective insofar as it is 

structurally sound. In addition to structural integrity, the project's 

remaining useful life and operation and maintenance requirements should be 

considered. An assessment must be made of the capability and willingness of 

the structure's owner to adequately maintain it. This is usually rather easy 

for structures owned by governmental units, but may be more problematic for 

structures that are privately owned. 

EXAMPLE 

Again using the New Jersey study, the problem is de~cribed in terms of 

both erosion and storm damages. Investigations to ascertain the existing 

without-project condition indicated shrinking beach widths throughout the 

81 
period of record, resulting in a majority of the shore front property in the 

southern communities of the study area having no dry beach; deterioration of 

seawalls and groins, leaving coastal structures increasingly susceptible to 

storm wave damage as the beaches continue to erode; and a net northward 

movement of littoral drift in the study area (at an increasing rate) toward 

Sandy Hook. Additional research documented the history of significant coastal 

storms causing widespread damage throughout the study area from a combination 

of wave attack, storm recession, and inundation. Post-storm damage reports 

from severe extratropical storms in 1962 and 1984, both resulting in disaster 

area declarations, were updated to 'current dollars to provide some measure of 

the monetary losses from damages caused by coastal storms representative of 

the study area. Due to the persisting problems of shoreline erosion and 

attendant degradation of protective structures, associated with expected 

increases in coastal development, analysts expected the potential economic 

losses and threat to human life and safety to continue to rise. 

STEP THREE: SELECT PLANNING SHORELINE REACHES 

The reach is the primary economic sub-unit of analysis. The beach 

length and associated upland areas are divided into "reaches" or "cells" 

throughout which the geomorphic conditions remain practically constant, and 

into "sub-reaches" or "zones" where development or use changes appreciably 

with stage or erosion patterns. 4 The type or level of existing protection 

are other criteria by which reaches may be established. Frequency of storms, 

tide levels, wind effects on water levels, cut and fill (erosion and 

4 The coastal engineer usually refers to cells and zones, while the 

economist may refer to reaches and sub-reaches. Although there are technical 

differences, the terms are often used interchangeably. 

82 
accretion) changes, and damage data may be used for .each reach; thus, data 

must be representative of the actual frequency of storm events and damage for 

that reach. A single reach may cover an entire developed area of a small 

community, in which case it is known as a "damage center", or it may cover 

only a few hundred feet of especially sensitive beach or estuary. Sub-reaches 

and zones may be established for the individual consideration of specific 

areas, particularly when a feature exists which app~eciably affects inundation 

and/or erosion conditions. 

Reaches are the primary geographic unit for planning. Plans are 

formulated with components that may cover a series of reaches. The hydraulic 

and hydrologic (H&H) effects and subsequent benefits of a project are 

calculated for each reach. Consequently, it is extremely important that reach 

selection be a joint effort by the project planner, the coastal or H&H 

engineer, and the economist. The hydraulic reaches and planning/economic 

reaches can be different; however, when possible, they should have common 

boundaries so that benefits can be displayed for each identified measure. 

When there is a doubt as to whether to begin a new reach, it is usually better 

to define too many reaches than too few. It is also wise to delineate and 

identify reaches in a manner that is consistent and acceptable to the entire 

study team so that all team members are referring to identical areas when they 

discuss a given reach. Similarly, within a given reach, a consistent 

numbering system for structures should be used by planners, real estate 

analysts, and engineers. 

In defining the littoral processes, the coastal engineer, along with the 

rest of the study team, must look at the requirements of the local interests 

(and/or sponsors) and determine how far along the shoreline the problem being 

83 
addressed will affect neighboring shorelines. Because reversals in littoral 

transport direction occur, and because different waves transport material at 

different rates, two components of the longshore transport rate become 

important. The first is the net rate; i.e., the net amount of material 

passing a particular point in the predominant direction in an average year. 

The second component is the gross rate; i.e., the total of all material moving 

past a given point in a year regardless of direction. Most shores 

consistently have a net annual longshore transport in one direction. 

Determining the net and gross annual amount of longshore transport is 

important in developing shore protection plans. Furthermore, determination of 

the potential transport rate may be as important as actual transport, 

particularly if the existing condition is sediment-starved. For instance, a 

large beach replenishment project may raise actual transport rates simply by 

providing material to the littoral system. 

The littoral cell is defined by the littoral processes. A project at 

times may encompass one, or only a short segment, of a cell, and at other 

times it may involve many littoral cells. Any measure which modifies the 

littoral processes will affect the entire cell in which it is instituted, even 

if the littoral cell is many miles in length, and the project only encompasses 

a few hundred feet. In that case, the study area will encompass a much larger 

area than if the littoral cell were only the immediate project area. Study 

reaches could be defined as: (1) the entire area updrift from the project 

site; (2) the immediate project site; and, (3) the entire area downdrift from 

the project site; or any other logical division acceptable to the study team. 

Reaches, for H&H considerations, are determined based on such elements 

as offshore features, beach slope, material composition, tidal influences, 

84 
uniformity of the beach profile shape, and cross sections of the back-beach 

area. It is usually this delineation of reaches from which incremental 

structural and economic justification and feasibility is established. From 

the economists' point of view, reaches are established primarily for the 

purposes of plan evaluation and display. Economists use reaches to determine 

the smallest desired breakdown of damages and benefits. Within each reach, 

breakdowns will be made of damages by land use category and by zones of 

inundation ariSing from the combined effects of water levels (a function of 

storm-induced surge superimposed on the water levels normally caused by 

astronomical tides) and attendant wave action. 

Shore protection management schemes often call for a combination of 

solutions. Solutions are based on changes, not only in hydraulic and physical 

considerations, but also on land use and political considerations. Reaches 

should be selected to help facilitate the formulation process by allowing 

breaks where there are significant changes in land use, changes in political 

subdivisions, and where there may be changes in the types of management 

solutions. 

In the New Jersey study, economic reaches were selected at a later stage 

in the benefits estimation process; namely, during the inventory of existing 

conditions, which would correspond to Step Six in this manual. Reaches were 

defined to assist in determining those areas most susceptible to flooding and 

to identify the primary areas for sample selection for structure inventory. 

The initial breakdown was by municipal boundary, followed by physical 

characteristics. The primary physical split was between the peninsula section 

85 
in the north (containing the communities of Sea Bright and Monmouth Beach) and 

the mainland areas to the south. These coastal segments were further divided 

into reaches by coastal dynamics and by the presence of such man-made 

structures as groins and seawalls. For example, within the municipal boundary 

of Long Branch, New Jersey, five reaches were selected based on whether the 

shore exhibited a beach without a seawall, a small beach with an upland 

seawall and functioning groin field, a small beach with no seawall and a 

functioning 'groin field, or a severely eroded beach with an ineffective groin 

field and an exposed seawall. This procedure resulted in the separation of 12 

miles of coast into 14 reaches. 

STEP FOUR~ ESTABLISH FREQUENCY RELATIONSHIPS 

A frequency is the number of times a specified phenomenon occurs in a 

given interval. For example, the water level may reach a height of 10 feet at 

a particular site 10 times in 100 years; or 20 feet or more of a beach is lost 

to a single storm once every 10 years. The same frequencies can also be 

expressed as an exceedance probability of 0.1, or an event with a 10% chance 

of being exceeded in any particular year. The elevation-frequency 

relationships (such as depicted in Figure 6) delineate the relationship 

between wave and water level and frequency of occurrence, while erosionfrequency relationships (which would appear very similar) delineate the 

relationship between periodic e.rosion (or accretion) and frequency of 

occurrence. The significant difference is that erosion may occur in one 

season followed by accretion in the next season; the net difference being the 

annual change. 

86 
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30 

20 

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i' 

J._~ V 

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10 20 30 40 50 60 7080 

Exceedance Interval in Years 

lL 

/ V( , 

y. 

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90 95 98 99 

Figure 6. Combined Exceedance Frequency Curve, Wave Height and Tide. 

87 
The elevation-frequency relationships, including some consideration of 

the duration of inundation, are combined with elevation-damage relationships 

(Step Eight) to derive expected annual inundation damages. As such they are a 

key element in the criteria for estimating the magnitude of expected storm 

damage. No estimate of expected annual damages can be made without first 

estimating how often a particular event may occur. At the same time, the 

analyst must also evaluate damage caused by storm-induced erosion and other 

storm-induced damages. 

As described in Chapter V of the NED Procedures Manual - Urban Flood 

Qamage, in riverine environments expected annual flood damages are derived by 

combining the information from three basic relationships: the elevationdischarge and discharge-frequency relationships, which the hydrologic and 

hydraulic engineers use to compute the elevation-frequency relationship; and 

the elevation-damage relationship, which is determined by the economist. 

Similarly, in coastal storm damage studies it is necessary to determine the 

frequency of damage at a particular site by synthesizing information from the 

elevation-frequency relationship (computed by the coastal hydrologic and 

hydraulic engineers) with the elevation-damage relationship (estimated by the 

economist in Step Eight). For damages occurring due to flooding, wave attack, 

or wind, the determining mechanisms are wave height and water level, which are 

both related to tide stage. Wave h~ight at the project during a storm may be 

depth-limited, in which case it would be directly related to water level. 

Water level in turn has tide stage as one component. Thus, the coastal 

engineer must typically derive the elevation-frequency relationship by 

combining wave height and water level, which are not highly correlated. Beach 

erosion and damages due to undermining are heavily dependent on storm 

88 
durations or the number of smaller storms occurring in a season. As an 

example, the storm of record for damage to many East Coast sites is the 1962 

Ash Wednesday northeaster. While the storm plotted relatively low on an 

elevation-frequency relationship, it persisted for several days. In general, 

the best techniques for evaluating erosion-frequency employ SOme combination 

of mathematical modeling, historical recession rates (where sufficient data 

are available), and professional judgement. A reconnaissance study which 

employed Monte Carlo simulation to derive the elevation-frequency and erosionfrequency relationships is provided in "Appendix C, An Example of Shoreline 

Damage Assessment." This example was excerpted from Appendix A of Santa 

Barbara County Beach Erosion and Storm Damage Reconnaissance Study.5 

EXAMPLE 

In the New Jersey study, frequency relationships were evaluated 

independently for each of the mechanisms responsible for structural damages: 

long-term erosion, inundation, recession, and wave action. This evaluation 

also included determination of the area subject to a particular frequency of 

the damaging mechanism, therefore incorporating the procedures corresponding 

to Step Five (described below). 

The historical rate of long-term erosion was determined by coastal 

engineers to be three feet per year. Extrapolating this rate for the 

projected fifty-year life of the project, the area subject to long-term 

erosion was· determined for the years 1990 through 2040. Based on discussions 

with the New Jersey Department of Environmental Protection, it was determined 

5 U.S. Army Engineer District Los Angeles, Santa Barbara County Beach 

Erosion and Storm Damage Reduction Reconnaissance Study, (Los Angeles: CESPL, 

1990). 

89 
that ongoing maintenance efforts would protect major structures such as the 

seawalls and state highway paralleling the beach. Long-term erosion would 

therefore be arrested at the leading edge of these structures by hUman 

intervention. 

Long-term shoreline change simulations were also performed for the New 

Jersey study by the Coastal Engineering Research Center (CERC).6 The GENESIS 

shoreline contour model was utilized to simulate the longshore sand transport . 

processes andlon~term shoreline change along the project reach. The GENESIS 

shoreline model is a generalized system of numerical models and computer 

subroutines which allows simulation of long-term shoreline change under a wide 

variety of user specified conditions. 

Inundation' frequency relationships were based on stage-frequency 

relationships also developed by CERe. These relationships (between the 

maximum still water level along the study sections and the interval in time 

between the expected recurrence of this water level) were also used for the 

design of the alternative beach fill cross-sections and for berm and seawall 

overtopping analyses. Since historical water level variations over an 

extended period of time were not available for the project area, a numerical 

model was used. In the model, northeasters were the dominant cause of rises 

in the still water level at the coast for the first 25 years; after 25 years, 

hurricanes dominated the surge level curves. These stage-frequency 

relationships are described in greater detail in the aforementioned CERC 

study. 

6 Detailed descriptions of the model are presented in Coastal Processes 

at Sea Bright to Ocean Township. New Jersey, U.S. Army Corps of Engineers, 

Coastal Engineering Research Center, (Vicksburg, MS: Waterways Exped.ment 

Station, 1986). 

90 
The storm recession-frequency data used for the economic analysis were 

also based on data developed by CERC. The stage frequency relationships 

(described above) were used as input for the numerical modeling of the storminduced dune and berm erosion. This task, performed in two stages, examined 

dune erosion of the existing conditions and dune erosion using alternative 

with-project 50-, 100-, and l50-foot design fill berm widths. The numerical 

model used to simulate dune erosion was based on a modified Kriebel-Dean dune 

erosion model which is a function of a single storm surge hyd+~graph. For 

both existing and with-project conditions, 120 northeasters and 275 hurricanes 

were generated for model input. The storm conditions were applied in the 

model for existing conditions to four typical existing shore profiles (cross 

sections) and for with-project conditions to the various desi.gn profiles. 

From the numerical model, maximum recession values were determined for the 

various storm events. Figure 7 displays maximum recession-frequency curves 

developed from this analysis, including allowances for variability. 

Finally, the wave attack frequency relationship in the New Jersey study 

was defined as the return period of the storm event which allows wave runup to 

destroy residential and commercial buildings within each economic reach. The 

wave attack line is the position in the uprush zone where the force due to the 

broken wave exceeds the critical force needed to destroy a structure. In the 

project area, the critical force necessary to d~s.troy a typical structure was 

determined to be a lateral force of 1770 pounds/foot, equivalent to a breaking 

wave height slightly over three feet. Limits of potential wave attack were 

delineated in the study area as wave zones for storms with return periods of 

25, 100, and 500 years. All delineations. assumed complete failure of seawalls 

and bulkheads, but damages to buildings were not considered for storms which 

91 
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RECURRENCE INTERVAL - YEARS 

Figure 7. Maximum Recession-Frequency Curves for 

Combined Northeasters and Hurricanes. 

Source: U.S. Army Engineer District New York, 1989. 

-

would not cause failure ,of these protective structures. The wave attack limit 

was calculated for the existing conditions and the alternative with-project 

beach profiles. Specific stru9tur.es subj ect to wave attack during the 25-

year, 50-year, and SOO-year storms were identified. The level of protection 

(in terms of storm return period in years) provided by existing beach widths 

and alternative with-project berm widths was determined for each economic 

reach. 

92 
STEP FIVE: OUTLINE AREA AFFECTED 

For purposes of this manual, the area affected refers to the part of the 

study area most directly affected by storm damage or long-term erosion. The 

geographic area would be bounded by the shoreline and the immediately adjacent 

inland areas subject to damage. Upcoast and downcoast boundaries would be 

limited by natural features such as headlands or inlets in most cases. 

Different coastal features in different parts of the country need to be taken 

into account. Sandy coasts with barrier islands, large estuaries, straight 

and unbroken beaches, or low-lying coastal plains would have significantly 

different areas affected by storm damage than rocky coasts with headlands, 

steep uplands or small, pocket beaches. 

The affected area must be adequately described for valid comparison with 

project alternatives. Natural shoreline features, as well as,man-made 

features and development, must be described. The primary purpose is to allow 

an accurate inventory of existing conditions, and to identify areas which may 

be protected by erosion/storm damage prevention measures. 

The procedure for outlining the area affected is to define the physical 

boundaries using the wave analysis and storm surge information from the 

hydraulic and coastal engineering analysis. The established frequency 

relationships from Step Four can be used together with topographic information 

to determine inundation effects. The wave analysis defines the expected storm 

events, time or duration of occurrence, direction and type of.waves, shallow 

water transformations and other effects. This will help to estimate wave 

attack damages and may also help to determine expected erosion. When combined 

with wave analysis and expected erosion, the shoreline geometry and topography 

will indicate which waterfront areas will be directly impacted by waves as 

93 
well as what structures and man-made alterations will be affected. Where 

appropriate, the effects of existing protective measures should be taken into 

account. 

The presence of features such as offshore islands and irregular bottom 

contours must be considered in determining the area affected by waves. The 

storm surge information, in conjunction with ground elevations, will indicate 

what areas would be inundated by various water levels. The inundated areas 

may include some or all of the shoreline in one or more littoral cells as well 

as parts of the adjacent floodplain some miles inland. Available floodplain 

information should be consulted. 

EXAMPLE 

In the New Jersey study, the area is described in terms of physical 

topography (e.g., the elevation and width of beaches, barrier islands, coastal 

plains, and headlands) and existing protective measures (e.g, seawalls and 

groins). The description of the area affected by particular frequencies of 

damaging mechanisms (long-term erosion, recession, inundation, and wave 

attack) were incorporated into Step Four (described above), the evaluation of 

frequency relationships. 

STEP SIX: INVENTORY EXISTING CONDITIONS 

An inventory is a survey of affected a.rea properties, including land, to 

assist in predicting potential damage. Types of information needed to 

evaluate properties in the affected area include susceptibility classification 

(including such factors as distance from the water, the existence of natural 

barriers, and construction materials), value, use, ground floor area, number 

94 
of stories, and elevation. This information is then used as a basic step in 

the computation of st.orm and/or erosion damages and damage reduction benefits. 

The existing condition inventory should be gathered by property use 

activity: residential. commercial, industrial, or public. During the 

inventory process, the economist should note areas likely to be developed or 

to change use during the planning horizon (e.g., small, dilapidated homes in 

an area with a growing population of condominiums and tourist facilities). 

This will facilitate making the future development projections. Physical 

damage estimates should also be made for transportation facilities, public 

utilities, vehicles, communications equipment and other property. These 

estimates will have two components: any damage caused by inundation; and 

damage or destruction caused by recession or erosion and the failure of 

support facilities. The economist should refer to National Economic 

Development Procedures Manual - Urban Flood Damage, Chapter 5, "Step Five: 

Inventory of Existing Floodplain," for inventory methodology. 

EXAMPLE 

In the New Jersey study, the level and density of residential and 

commercial development and the value of residential and non-residential 

structures, contents, and roads and utilities in the immediate project area 

were described based on a structure inventory and Monmouth County tax 

assessments. A structural data base was generated through a survey of 

structures adjacent .to the project area including buildings, utilities, 

bulkheads, seawalls, and roadways. The building data were obtained through a 

windshield survey of the area using topographic mapping with a scale of one 

inch to 200 feet with a two-foot contour interval. Information on the type of 

95 
building, location, setback distance, mid-point distance, building size, 

number of stories, the existence of a basement, elevation, building material, 

and quality were collected. For utilities, roads, and structural measures the 

inventory data were taken from topographic mapping and primarily targeted 

toward physical characteristics such as size and length, in order to assign a 

replacement value. A key element in both aspects of the structure inventory 

was the front of structure setback and the mid-point setback data, used to 

locate each structural element relative to the water line. This was the 

primary mechanism used to trigger damage due to long-term erosion, storm 

recession, and wave attack. 

The data collected were used to categorize the structure population into 

groups having common physical features. Data pertaining to structure usage, 

size, and stories assisted in the stratification of the building population. 

For each building, data were also gathered pertaining to its damage potential 

including its main floor elevation lowest opening, construction material, and 

proximity to the water. Replacement value was calculated for the residential 

and commercial structures using standard estimating guides in conjunction with 

size data. 

STEP SEVEN: DETERMINING HOST LIKELY WITH- AND WITHOUT-PROJECT CONDITIONS 

Alternative water resource ma~agement ,plans are formulated and evaluated 

on the basis of the most likely conditions expected to exist with and without 

implementation of each of the plans identified for analysis. The purpose of 

forecasting conditions expected to exist with and without each plan under 

consideration is to isolate the changes that are expected to occur as a result 

of implementation of the plan, from those that would occur if the plan were 

96 
not implemented. Without-plan conditions, therefore, are the conditions 

expected to prevail if no Federal action is taken, while with-plan conditions 

are those expected to prevail with implementation of a plan. 

The without-plan condition is an assessment and forecast of the storm 

damage or erosion problem, assuming no action is taken by the Corps to 

alleviate it. If storm damage prevention works or any other action are 

imminent or likely without Corps action, those works and actions should be 

considered to be part of the without-plan condition. Imminent works and 

actions include measures that are under construction; funded storm protection 

measures; development under construction; development limitations as specified 

under the National Flood Insurance Program, Executive Order 11988, and Coastal 

Zone Management Plans; and any state and local regulations in effect. Since 

the without-plan conditions sometimes include plans which have yet to be 

approved or may be speculative, all assumptions should be carefully explained 

and justified. 

Existing development and activity can be expected to remain in place, 

unless facilities are in deteriorated condition, abandoned, or are to be moved 

or replaced. Structural assessments should be made of existing storm 

protection works to determine the realistic degree of protection which they 

provide. 

Any changes in population, land use, affluence, or intensity of use 

expected as a result of implementation of a plan, should be included in the 

assessment and forecast of with-plan conditions. 

The level of detail required in collecting data and forecasting future 

conditions depends on factors such as type of study (e.g., reconnaissance or 

feasibility), available time and money, sensitivity of project formulation and 

97 
justification to changes in storm damage prevention benefits, and interests 

and concerns of the local sponsor, if applicable. Because of the compressed 

time frame andamoun.t of money available for reconnaissance level reports, the 

amount of qetail required is less than what is req~ired for a feasibility 

study. The. reconnaissance study should focus on without-project conditions, 

while the feasibility study should provide detailed formulation. ~n addition, 

a lesser level of effort in primary data collection may be appropriate when 

data are available for an area with similar development and economic activity 

and shoreline,geologic, and other features, including littoral processes. 

However, extreme caution should be exercised when using data from other areas, 

especially in planning beyond the reconnaissance study, to ensure that the 

areas are indeed similar. 

FACTORS TO CONSIDER 

Development of forecasts of future conditions requires consideration of 

human responses to long-term erosion and coastal storm damage. 

Response to Long-Term Erosion. As long-term erosion occurs, individuals 

and communities will respond by taking action to protect, relocate, or abandon 

existing properties~ In addition, action maybe taken to limit future 

development. During the development of the forecast of future conditions, the 

economist must determine the most likely course of action, which will then 

become the basis for the analysis and forecast. It should be noted that the 

most likely action to be taken could change over the planning hori~on; 

property owners may take action to protect properties initially and later to 

relocate or abandon the structures. 

98 
The most likely action should be based on institutional factors which 

may vary greatly from state to state, and the assumption of rational economic 

behavior (e.g., property will be protected as long as the perceived 

incremental cost of protection does not exceed the perceived remaining value 

of the property). On this basis, in many cases it can be expected that 

efforts to protect may continue until such time that total loss of the 

property is imminent and further occupation or use of the property becomes 

unsafe. State Coastal Zone Management Plans (CZMPs) or other zoning 

ordinances may prohibit such individual protection or replacement or repair of 

some damaged structures. All assumptions and limiting factors should be fully 

documented, and discussed among the study team to prevent conflicting 

assumptions by different team members. 

Response to Storm Damage. Individuals and communities may also respond 

to storm damage to property in a variety of ways, including relocation, 

abandonment, and repair or reconstruction. In addition, building and zoning 

codes may be changed. As with the response to long-term erosion, the 

economist must determine the most likely course of action which would be 

taken. In general, it should be assumed that the most likely course of action 

will be based on rational economic behavior, whereby individuals and 

communities attempt to make their decisions on the basis of marginal costs and 

benefits. Therefore, it is assumed that property would be replaced or 

repaired as long as the present value of future storm damages is less than the 

cost of relocating the property. 

99 
DATA SOURCES 

A major problem in inventorying existing, and predicting future, 

conditions is obtaining quality data for use in making the evaluation. 

Primary data sources are preferable for obtaining specific and accurate 

information, but using such sources is often too costly or time consuming. 

Secondary sources are usually less expensive, but caution should be exercised 

to ensure that the data are specifically applicable to the study area. 

Primary data include that collected firsthand by the study team through. 

observations or surveys. Secondary data are derived from published sources, 

such as government reports and databases, newspapers, and technical books and 

periodicals. Some of the general sources for various types of information 

needed for storm damage analysis, in addition to information available from 

within Corps district offices, are summarized in Table 2. 

100 
TABLE 2 

POTENTIAL DATA SOURCES BY SUBJECT 

Subject Potential Data Sources 

Land Use A,B,C,J 

Land Values A,D,N 

Coastal Geology 

Historic Coast Line 

E,F,K,L,M,O 

A,B,E,F,H,J,K,L,M,N,O 

F,G,H,K,L,M,N 

E,F,H,K,L,M,O 

Storm Intensity and Pattern 

Local Littoral ProcesseS 

SOURCES , 

.A ... County Office of Assessment and Taxation 1/ 

B == 

C == 

D ... E == 

F == 

G == 

H == 

I = 

J == 

K = 

L ... M == 

N ... 0 -

County Office of Zoning and Land Use 1/ 

county o~ Municipal Building Departments 1/ 

County Register or Recorder of Deeds 1/ 

Geological Survey, U.S. Department of Interior 

U.S. Army Coastal Engineering Research Center 

National Weather Service, U.S. Department of Commerce 

National Ocean Service, U.S. Department of Commerce 

Coast Guard, U.S. Department of Transportation 

Area Port Authorities 

Local Universities 

Sea Grant Institutions 

Other Oceanographic Institutions 

Newspapers 2J 

State Geologic Survey 1/ 

1/ Name of the office may vary from state to state. 

2J May carry weekly compilation of real estate transactions, etc. 

Old copies may have descriptions and pictures of major storms. 

DISTINCTION BETWEEN STORM AND LONG-TERM EROSION DAMAGE 

Because Federal interest and budgetary policies on Corps participation 

in storm damage analysis and long-term erosion control plans may differ, it is 

essential that forecasts of future conditions distinguish between potential 

damages from storms and potential damages from long-term erosion. For storm 

101 
damages, care must also be exercised to separate damages due to the storm from 

storm-induced erosion damages. Forecasts of future conditions should separate 

potential damage effects on the basis of the following definitions. 

As defined in Chapter 1, long-term erosion consists of the loss of land 

along the shoreline due to littoral transport and to wave action from storms 

with an exceedance frequency of up to one year. 7 Storm damage consists of 

the loss of land and loss or damage to associated capital improvements and 

other property along the shoreline due to erosion, inundation, wind, and waves 

from storms with an exceedance frequency of more than one year. 8 

A key factor in the analysis of long-term, wave-induced erosion is the 

determination of whether the loss of land is temporary (seasonal) or longterm. For the purposes of the analysis of long-term erosion, temporary loss 

of shoreline land should be considered to be the loss occurring annually due 

to a seasonal increase in the intensity of wave action, with the shoreline 

7 Long-term erosion is determined by comparing maps, photos, and surveys, 

or other available historical records, that span a period of several years or 

decades. The cumulative shoreline changes measured from these data sources, 

therefore, probably include the net effects of storms with exceedance 

frequencies greater than one year. In order to account for long-term erosion 

effects and yet keep them separate from storm-related damages, the procedure 

used by one Corps district is to move the position of the shoreline landward 

over some given time increment and evaluate potential storm damages for each 

future shoreline position. Structures and other features overtaken by the 

future shoreline position during the time increment are removed from the 

structure inventory prior to the evaluation of future storm damage. Inherent 

in this analysis is the assumption that storm erosion losses are temporary; 

the shoreline is assumed to be completely restored to its pre-storm position 

following the passage of the storm. 

8 Although "normal" erosion is usually defined on a study-by-study basis, 

the one-year exceedance frequency demarcation between erosion wave action and 

storm wave action is a generally accepted, albeit arbitrary, designation. 

Nevertheless, shorelines can be impacted by waves with exceedance frequencies 

of greater than one year that are still not considered "storm waves." There 

can be considerable non-storm, year-to-year variation in the wave climate at a 

site. 

102 
being restored to its historical position annually as wave action moderates. 

Analysis of long-term erosion should take into account potential impacts on 

the rate of erosion due to natural (e.g., land slides and land subsidence or 

uplift) and man-made (e.g., bulkheads, seawalls, revetments, breakwaters, 

groins, jetties, and channels) alterations to the shoreline. MaJor 

alterations to the shoreline· or offshore areas (either natural or man-made) 

may require the analyst to disregard all data collected prior to the 

alteration. 

EXAMPLE 

In the New Jersey study, future with-project and without-project 

economic conditions were estimated using the inventory of existing development 

conditions as a basis. Projections of future population by the New Jersey 

Department of Labor indicated that Monmouth County would continue to grow at a 

faster rate than the state average through the year 2020. Population trends 

in the project area communities, though varied, indicated increasing numbers 

of residents along the coastline. Forecast development in the project area 

mirrored the regional trend toward increasing townhouse .and condominium units 

and toward more year-round housing units (as opposed to seasonal units), both 

in percentage of units and in numbers. Growth in the value of homeowners' 

contents were projected to increase at the same rate as that of per capita 

income for the State of New Jersey, obtained from the 1985 OBERS Regional 

projections produced by the Bureau of Economic Analysis. Future content 

values were not allowed to exceed 75 percent of associated structural values. 

Future with- and without-project conditions were estimated for damages 

caused by long-term erosion and by storm mechanisms. Under without-project 

103 
conditions, the long~term erosion problem documented in Step Two was projected 

to continue. Because of the loss of beach material northward due to littoral 

transport, and because the beach itself is the only source of that material, 

it was projected that the beach would continue to erode at the historical 

10ng~term erosion rate of three feet per year. The long-term erosion would 

result in the reduction of berm area, which acts as a natural buffer for both 

unprotected properties and the protective coastal structures themselves (e.g., 

seawalls and groins). Therefore, deterioration of the seawalls and groins was 

expected to continue, making them increasingly susceptible to storm wave 

damage and failure. Due to continuing shoreline erosion with attendant 

degradation of protective structures and increased coastal development, the 

potential economic losses were projected to rise. Under with-project 

conditions, the proposed project would halt long-term erosion as a result of 

implementing a feeder beach and an ongoing beach nourishment program. 

However, under both with- or without-project scenarios, it was 

determined that the seawall and state highway paralleling the beach in the 

northern sections of the study area would be protected through the State of 

New Jersey's ongoing maintenance efforts. Long-term erosion would be, 

therefore, arrested at the leading edge of these features, although damage 

and/or failure from storm-induced recession or wave attack could not be 

prevented through seawall maintenance. Further south, structures destroyed by 

long-term erosion without the project were removed from the analysis for 

future years as it was determined they would not be reconstructed because the 

site was destroyed. 

Recession, inundation, and wave attack damages were analyzed for future 

without- and with-project conditions. In the absence of the project, 

104 
butldit;l~s destroyed were assumed to b.e rebuilt unless subject to wave or storm 

recession damage from storms with a recurrence interval of 1.5 years or less. 

In areas protected by the seawall, total rebuilding was assumed based on the 

perception of protection provided by the seawall. This was based on a review 

of existing development which presently reflects this proximity to the 

shore1tne. For residential structures, the replaced building was considered 

to be elevated to meet the National Flood Insurance criteria. 

Residual recession and wave attack damage under the with-project 

conditions were evaluated using the same methodology excluding long-term 

erosion since project maintenance would prevent its occurrence. Setback and 

midpoint distances were adjusted for the additional beach width and the 

seawall failure frequency was adjusted to reflect the increased level of 

stability provided by the project. 

STEP EIGHT: DEVELOP DAMAGE RELATIONSHIPS 

After the inventory and appraisal of flood-prone property, the 

computation or selection of damage relationships is the next important task 

for the economist. This section addresses the process of developing and 

selecting appropriate damage functions to meet the requirements of a 

particular situation. Damage relationships describe the expected value of 

structural or contents damages caused by various factors, such as depth of 

flooding, duration of flooding, sediment load, wave heights, amount of 

shoreline recession, and warning time. This section also includes a 

discussion of when it is necessary to compute site-specific functions and when 

it is. possible to use generalized damage relationships. 

105 
Depth-damage relationships developed for flood control studies are based 

on the premise that water depth, and its relationship to structure elevation, 

is the most important variable in determining the expected value of damage to 

buildings. Similar properties, constructed, furnished, and maintained alike, 

and exposed to the same flood stages and forces, may be assumed to incur 

damages of similar magnitudes or proportion to actual values. These damage 

functions are often continuous in form. However, a very large percentage of 

coastal storm damages are related to erosion (i.e., undermining of structures) 

and/or wave forces rather than actual inundation of structures, and often 

discontinuous or stepwise damage functions are more indicative of the actual 

damage potential. For example, minimal damage may occur up to a determined 

point, followed by a large "step" in damage as part of the set of structures 

fail, followed by little or no additional damage, followed in turn by further 

structural failure and catastrophic damages, and so on. Additionally, wave 

uplift can be a significant source of damage for structures such as single 

family residences and piers built on pilings. 

Undermining damage is related to structural composition of the building 

and foundation (e.g., concrete slab, standard foundation, piling) and depth of 

foundation or piling relative to composition and integrity of the surrounding 

soil. There is no widely accepted, quantified relationship in the United 

States between any of these factors and the extent of damage, so the analyst 

must use "best judgement" and experience in the area to make the appropriate 

decision. Often, a structural engineer or insurance appraiser may need to be 

consulted. In this step, and in the next step, the objective is to determine 

how much damage occurs with various types of events. Two basic approaches are 

discussed below. 

106 
One method of determining damage relationships is to estimate the 

damages that occurred during actual storm events, usually from extensive 

interviews with residents, business proprietors, and local officials. During 

the interviews, damages are also estimated for other types of events (lesser 

or greater frequency storms) to the extent possible. Even using extensive 

interviews, however, it is not always possible to separate damages from the 

various damaging mechanisms, particularly when inundation, waves, recession, 

and wind all affect the structure. Moreover, conducting interviews is a timeconsuming and expensive process for most study areas. Another limitation is 

that previous threatening events and subsequent damaging events may be 

sufficiently different. For example, recent large storms may have only 

damaged protective features, such as dunes or barrier islands, with little 

damage to properties. These storms, however, have exposed properties to 

future damage by even smaller events. Therefore, using historic damages based 

on storm magnitude would underestimate the damages that might now occur. 

A second approach is to use generalized inundation-damage relationships 

from other areas, often derived by computer-oriented analysis. This approach 

is described in detail in the NED Procedures Manual - Urban Flood Damage. 

With this approach, special care must be exercised to avoid double counting 

(i.e., to separate erosion damages from storm damages) and to use data only 

from areas where the damage relationships are similar. If this approach is 

used for inundation damages, wave attack may need to be estimated on a 

structure-by-structure basis, and erosion damages will need to be evaluated 

separately. 

The major criterion in selecting damage functions is the similarity of 

susceptibility relationships. Damage functions are influenced by a number of 

107 
variables. Variables found to be significant in regression analysis can be 

used in computing reliable damage relationships. Table 3 summarizes the major 

hydro-meteorological, structural, and institutional factors that significantly 

influence the amount of damage. 

While most analysts involved in flood damage assessment are aware of 

most of these factors, it is rare that any of these factors has been isolated 

as part of a predictive function. It is less difficult to apply functions 

where the factors are reasonably close to the situation to which they are 

being applied. For example, damage functions computed for the New Jersey 

coast area may be applicable to sites along the Massachusetts coast, where 

storm regimes are similar, but unsuitable for use at Yest Coast locations, 

where storm regimes are very different. 

108 
TABLE 3 

VARIABLES THAT INFI1JENCE DAMAGE RElATIONSHIPS 

VARIABLE EFFECTS 

HYDRO-METEOROLOGICAL VARIABLES 

Storm Intensity 

Duration 

Frequency 

Ice Effects 

Storm intensity is a major factor aggravating structure 

and content damage. High water level, wind and wave 

forces create greater danger of foundation collapse and 

forceful destruction of contents. Factors contributing 

to storm intensity are water height; swell size; wave 

height, steepness, and direction; and wind velocity. 

Duration may be the most significant factor in the 

destruction of building fabric and lead to erosion and 

other damages. Continuous high water levels accentuate 

the effects of high waves. Continued saturation will 

cause wood to warp and rot, tile to buckle, and metal 

objects and mechanical equipment to rust. Agricultural 

land will sustain greater and longer term damage from 

sustained inundation, particularly when salt water 

saturates the soil. Long duration storms of a smaller 

magnitude may cause more damage and greater total erosion 

than a larger, short duration storm. 

Repeated saturations can have a cumulative effect on the 

deterioration of building fabric and the working of 

mechanical equipment. Frequent, smaller storms may 

result in more cumulative erosion (or prevent material 

from being carried onto the beach) and damage than a 

single large storm. When a large storm follows several 

smaller storms, potential damage is greater. 

This variable is usually a factor only on the Great 

Lakes. Ice can cause structural failure of many types of 

materials and can be particularly damaging and erosive. 

However, the formation of "fast ice" (solid sheets 

connected to the shore) can provide some degree of 

protection from storms. 

109 
STRUCTURAL VARIABLES 

Building 

Material 

Inside 

Construction 

Condition 

Age 

Content 

Location 

Steel frame and brick buildings tend to be more durable 

in withstanding inundation, but more susceptible to 

corrosion and 'buckling than other more flexible material 

such as dimensional lumber. 

Styrofoam and similar types of insulation are less 

susceptible to water damage than fiberglass and wool 

fiber insulation. Plaster and most types of drywall will 

crumble under prolonged inundation. Waterproof drywall 

will hold up for long periods of inundation. Paneling 

may be salvageable when other wall coverings are not. 

Even the best building materials can collapse under 

stress if the construction is poor (e.g., below accepted 

codes) or is in deteriorated condition. Building 

condition should be a major determinant of depreciated 

replacement value. 

Age may not be a highly significant factor in itself, 

except that it may serve as an indicator of condition and 

building material. It would be more accurate to survey 

the other factors separately. 

Arrangement of contents. is an important factor in 

determining damage relationships. These relationships 

could be expected to be somewhat homogenous for 

commercial business, particularly chain stores. 

Industrial property should be surveyed individually to 

determine how the arrangement of contents will affect the 

damage relationship. 

INSTITUTIONAL FACTORS 

Storm Warning Reductions in both content and structural loss can be 

made through emergency preparedness and evacuation 

activities when there is adequate warning, and resources 

are available to fight the storm effects. The potential 

for prevention of losses is somewhat less than in a 

riverine flooding situation due to the greater likelihood 

of a dangerous storm situation requiring evacuation of a 

wide area. Prevention of structural damage is also more 

difficult due to the forces of wave action. On the other 

hand, there is often a longer response time available 

because major storms such as hurricanes may be predicted 

days in advance so that, even though actual landfall 

location is uncertain, local officials have time to 

prepare. 

110 
GENERALIZED FUNCTIONS 

Generalized damage functions are computed from either post-storm surveys 

or synthetic estimates. Generalized functions are sometimes as accurate as 

building-by-building estimates of susceptibility, but they should be 

field-checked whenever they are applied. Knowledge is required of the 

critical variables that could influence damages in the area where the 

generalized curves were derived, and in the area where they might be applied. 

This is an area where the economist and the coastal engineer must work 

especially close together to obtain defensible damage estimates. Please 

consult the NED Procedures Manual - Urban Flood Damage for more information on 

generalized damage functions. 

DAMAGE VAUJATION 

Basic estimates of losses 'for buildings, roads, protective works, and 

other development features should be prepared at current price levels for the 

existing state of development of the problem area. For long-term erosion, 

historical damages may be used as a basis for estimating future losses to 

existing developments. Use data for as long a period as reliable records are 

available. All values should be adjusted to current price levels; any changes 

in costs of both normal and extraordinary repairs and maintenance should be 

noted. 

Appropriate adjustments should be made in basic damage estimates to take 

into account: 1) any factors which would tend to modify rates of shore 

erosion; 2) accrued depreciation or maintenance resulting from normal wear or 

aging; and, 3) probable trends and nature of developments and activities in 

the problem area, based on the most probable economic use of the area in the 

111 
absence of suitable protective measures. Local government units and planning 

bodies should be consulted. 

Probable damage prevention benefits should be estimated for prospective 

development conditions that would occur in the absence of the project, by 

correlating the adjusted damage estimates with expected project effects. 

Project effectiveness should be estimated on the basis of experience and 

knowledge of beach erosion control. 

Although shore protection plans are normally designed to stabilize the 

shore or provide sufficient protective beach so that storm erosion will not 

damage on-shore installations, protection may not be feasible against 

occasional severe storms that cause temporary beach profile adjustments and 

severe recessions. Readjustment after the storm may result in recovery of 

temporary losses of land, but damages (especially to developed property) not 

prevented by the plan should be taken into account. 

Damages from tidal or hurricane flooding which would not be prevented by 

the beach erosion control plan must be excluded from the benefit estimates. 

However, an adequate protective beach can ordinarily be expected to reduce 

flooding and damage due to wave runup or wave attack, except in the most 

severe storms and hurricanes. The credit taken for prevention or reduction of 

such damage should be based on an analysis of the level of protection which 

can reasonably be expected from a project. 

Erosion, accretion, subsidence, uplift and littoral transport can 

greatly affect the susceptibility of property to future damages. A series of 

aerial photographs, taken in different seasons and over a period of years, 

should be consulted when available. The ideal situation would be to have. 

photographs of each season for each of several years, and photographs both 

112 
before and after significant events. In practice, the best available is 

usually only a few different years, and sometimes a series of photographs 

taken several weeks or months before and immediately after a very large storm. 

Damages at the same stage in different floods may vary with seasonal 

flood characteristics. There may be seasonal differences in wind velocities, 

duration, debris, and natural protection (e.g., beach profiles). Estimated 

damages might be correlated with these seasonal factors and the probabilities 

of floods occurring at any particular time of the year. This seasonality 

situation is similar to that found with agricultural flood damage estimates as 

discussed in the NED Procedures Manual - Agricultural Flood Damage. Content 

damage relationships may vary seasonally as well. In many areas, a 

significant percentage of residential units are summer or vacation homes, and 

these are infrequently occupied or are boarded-up for the winter. In these 

areas, many of the commercial units are also closed for the winter, or their 

inventories may vary seasonally by orders of magnitude. 

EVAWATION OF COMMERCIAL LOSSES 

Inventory of the study area will indicate the nature of comme.rcial 

development, and the extent to which sampling procedures may be applicable or 

specific inspection and appraisal required. Seasonal variation can be most 

dramatic for commercial contents for the reasons cited above. For interviews 

and inspection, the questions in the set of OMS-approved questions may be used 

for, or adapted to, commercial properties. 9 

9 The approved list of questions was distributed by CEWRC~IWR t~ Major 

Subordinate Commands and District Commands in 1984 by DAEN-CWP letter; for 

more information, contact the Economic an~ Social Analysis Branch (CECW-PD), 

HQUSACE. 

113 
EVALUATION OF DIRECT PHYSICAL LOSSES 

Actual or potential damages can be estimated by the normal methods of 

estimating repair or replacement costs. Where available, repair bills and 

company records also provide an independent source. As in other cases of 

direct physical damages, losses attributable to floods must be separated from 

repair costs that restore accrued depreciation. Shortened physical life 

(accelerated depreciation) of damaged items, non-recurring damages, and those 

preventable by good housekeeping, prudent management, or prompt action upon 

receipt of storm warning, should be eliminated from estimates of prospective 

damages. 

EVALUATION OF LAND LOSS 

Anticipated damages from land loss due to erosion may be computed for 

private lands as the market value of the average annual area expected to be 

lost. This should be determined from an analysis of adjacent nearshore lands 

of similar character for land use conditions ,expected in the absence of the 

project. According to ER 1165-2-130, other valuation methods are potentially 

acceptable, if it can be shown that the use of nearshore values does not 

provide a realistic estimate of the value of lost land. The decision to use 

another value must be properly explained, however. 

Nearshore values are used because there will usually be "beach front" 

property. Erosion of the beach front property results in the property 

immediately behind the eroded land becoming the new beach front, usually with 

114 
the higher value attributed to the previous beach. front property.10 

Therefore, the value of the lost land is not that of the beach front, but that 

of the nearshore land. Often, this is manifest in a landward shift in 

shore-related uses. For example, beach front commercial property is destroyed 

by .a storm or erosion, but is rebuilt at the "new" beach front which was 

previously lower quality commercial or residential property. As it is 

replaced by the high value "new" beach front commercial, the nearshore 

commercial uses shift further inland. This displacement and shifting 

continues until a.natura1, economic or institutional barrier to development is 

reached. It is therefore the property which is at or near this natural 

barrier that is "lost", rather than the beach front property until such time 

as all the property suitable to development is (effectively) fully developed 

and further erosion results in a net reduction of development. This is the 

purpose of the requirement to use nearshore values to compute land loss 

benefits. State and/or local zoning ordinances will dictate how new or 

replacement development may occur in the coastal area. 

When market values are not available (or are unreliable or include 

speculative value), the value of land may be computed as the capitalized 

annual net income the land can produce. Anticipated damages due to storm 

erosion may be computed by correlating the value of historical land losses 

with particular storm events to develop a storm-damage curve to be used in 

estimating future losses. 

10 If an area is experiencing extremely high erosion rates, however, the 

"new" beach front property may not be as valuable as the previous beach front 

property. High rates of erosion are usually accompanied by the destruction of 

ocean front structures. Even though the debris left as a result of the 

destruction may eventually be removed, the quality of the beach is normally 

not as good as beaches in more stable areas. 

115 
EVALUATION OF PUBLIC DAMAGES 

Public property, for purposes of damage appraisal, can be considered to 

include all property owned by the various agencies of government or by 

charitable associations for the service of the public. Public property 

damages are principally apparent in the form of direct physical damage, or in 

the physical costs associated with insuring continuation of public services. 

The loss of public income may result if services provided on a user fee basis 

are interrupted. For example, the interruption of utility services such as 

water and electricity which are provided by a public entity would result in a 

net loss of public income. Besides streets, which are classified with 

transportation facilities and public power stations, public goods and services 

that may be adversely affected by storm damage and erosion include parks, 

recreational facilities, all public or semi-public buildings, water supply 

systems, sewerage systems and treatment plants, pumping stations, and fire and 

police protection facilities. Specific inspection and appraisal of damage 

potentials is required in each case. 

Care must be taken to exclude losses, particularly for parks and other 

recreation sites which would be caused by weather (e.g., fewer visitations in 

winter or during especially stormy periods either with or without damage to 

the recreation facilities), transfers (recreationists transferring to other 

undamaged sites), or other seasonal factors. Degradation of the recreation 

experience can be counted as a damage, quantified through unit day values or 

the travel cost or contingent value methods. 11 

11 IWR. Report 86-R-4, NED Procedures Manual - Recre.ation. Volume I, 

Chapter 3, provides information on the principles, assumptions, and 

appropriate use of the three recreation valuation methods (i.e., unit day, 

travel cost, and contingent value methods) recognized by the U.S. Water 

Resources Council. 

116 
Physical damages to public property can be evaluated by the restoration 

or relocation methods of appraisal appropriate for the problem being studied. 

Estimates of such damages and the costs of related emergency and normal 

services should be prepared in cooperation with the agency involved. The 

highly variable nature of other public facilities makes use of a standard form 

generally impractical, and appraisal computations should be adapted to each 

case. 

It may be found that many public facilities or services overlap several 

reaches or cells and that damages cannot readily be assigned to specific 

locations. Breaks at anyone or several points in water supply or sewerage 

systems may produce the same associated losses to all customers or taxpayers 

including those in other reaches or on high ground. Damage to public 

property such as streets, sidewalks, lighting, or water and sewer connections, 

for example, may duplicate part of the appraisal of specific properties 

served. 

EVALUATION OF NON-PHYSICAL LOSSES 

When researching or surveying based on historical storms, emergency 

costs should be separated into two categories. These costs include those 

incurred because of the damage (or threat of damage) which might be prevented 

by a Corps measure, and those incurred to protect from the high winds, 

rainfall, and other destructive forces which would occur even with the best 

possible protection. Frequently, data are only available for one significant 

storm. As discussed in the NED Procedures Manual - Urban Flood Damage, 

applying the same loss per structure to other storms based on the number of 

properties affected or the geographical extent of damage is usually an 

117 
adequate approach. The percentage reduction in emergency costs for coastal 

storms is often much less than for riverine flooding situations. Only those 

emergency costs actually prevented may be counted, as the threat of a 

hurricane, for example, may precipitate emergency action regardless of the 

presence or absence of .!l Corps project. 

EXAMPLE 

In the New Jersey study, a sample population of buildings was se1e.cted 

for on-site inspection to determine damage potential. Findings from the onsite interviews conducted for the sample population were then used to develop 

generalized depth-damage relationships applicable to the overall population. 

A total of 214 site investigations, representative of two percent of the total 

structure population, were conducted. The inventory population was stratified 

according to physical characteristics (e.g., residential structures were 

separated into 15 categories, such as colonial, ranch, split level, bungalow, 

mobile home, duplex, townhouse, garden apartment, and high-rise), structure 

usage (e.g., various categories of commercial and industrial enterprises, 

offices, recreational facilities, municipal services, and others), and 

susceptibility to flooding for the selection of a represen~~tive sample. Care 

was taken to assure that each group in the stratified population was 

represented in the sample population. On-site inspections were conducted at 

the sample locations to determine damage potential for various flood depths 

and to determine historic damage where available. The historic damage data 

were used to calibrate the potential damage at each structure by providing a 

known reference point in the depth damage evaluation. The final population 

118 
sample distribution is listed in "Appendix B, An Example of NED Economic 

Benefits Analysis." 

Generalized damage functions were generated for physical damage, 

emergency costs, lost income, and residential content damage. These damage 

functions reflect damages per square foot of structure size, which were then 

applied to each structure to determine damages at one foot increments of flood 

stage. For non-residential structures the damage surveys evaluated the depthdamage relationship for physical losses, lost income, and emergency costs 

based on an assessment of the sites visited. For the residential structures, 

Flood Insurance Administration (FIA) curves were used to develop the physical 

damages based on total value of contents and structure. Lost income and 

emergency costs were based on interview data. 

The analysis of lost income benefits was based solely on residential 

damage surveys, and therefore eliminated double counting business and 

household lost income. it also avoided transfers of economic activity, which 

are prevalent when the loss of income to local business firms is measured. 

Double counting of income loss and emergency costs was avoided by considering 

the evaluation of emergency costs, such as flood fighting, evacuation, and 

clean up, net of any income losses identified during the damage surveys. 

Also, an upper limit of 40 hours of income loss per household was assumed to 

eliminate survey responses which did not accurately distinguish between income 

lost due to damage to place of employment or time spent for clean up and 

repair. 

119 
CALCUlATING BENEFITS 

The steps involved in calculating benefits include determination of 

damage-frequency relationships (Step Nine), computing expected average annual 

damages (Step Ten), and estimating total storm damage reduction and erosion 

prevention benefits (Step Eleven). For Steps Nine and Ten, two alternative 

computational methodologies may be used depending on the type and complexity 

of the erosion or storm damage situation. The first is the more traditional 

analytical technique similar to that used in most flood damage or shoreline 

change studies. The second is a simulation or Monte Carlo methodology which 

has been used in many other types of analytical applications with multiple 

independent random events. 12 The two techniques are compared in Steps Nine 

and Ten below. 

Briefly, the traditional approach relies on the damage-frequency and 

erosion-frequency relationships to quantify probable damages and benefits in a 

given year. Damages are based on the probability of occurrence of each 

damaging event using the hydrologic and economic conditions that prevailed at 

that time. For example, the probable damages associated with a 100-year event 

and a lO-year event are, respectively, .01 and .1 times the damages estimated 

for each of these events in that year. The summation of all probable damages, 

over the range of events, defines expected damages for that year. 

Monte Carlo, or similar simulation models, are (normally) computer-based 

mathematical replications of the way the real world reacts to a series of 

unrelated random events and situations. Unlike the standard analytical 

methodology which develops damages and benefits based on probabilistic 

12 The term "Monte Carlo" is derived from the comparison of results from 

simulated mUltiple random events to the many games of chance, such as roulette 

or craps, popular in the casinos of Monte Carlo, Monaco. 

120 
averages, simulation techniques use the randomness associated with the 

variables (in this case, erosion rates or severity and duration of storms, for 

example) to generate a number of life cycles (called "games" in simulation 

terminology). 

Each game represents one possible sequence of the model life. 

Typically, 100 or more games are played through the model (1,000 or 10,000 

might be required if rare events could significantly alter the results), and 

relevant statistics are kept by the program to show the analyst where the 

greatest variability and associated risk lie within the model. From a typical 

model, the analyst can expect to obtain average annual damages (and/or 

benefits) as well as statistics about the likely distribution of the damages 

(i.e., the risk analysis), and, with most simulation or Monte Carlo packages, 

graphical displays of the results. Although such long-term trends as land 

subsidence are difficult to detect'and can influence expected damages and 

benefits, Monte Carlo techniques usually assume no such trends. 

Use of the Monte Carlo method has not been widespread in shore 

protection studies. One recent study which did employ Monte Carlo simulation 

in damage assessment computations, however, is the West Onslow Beach and New 

River Inlet. North Carolina (Topsail Beach) Hurricane Protection and Beach 

Erosion Control Feasibility Report. 13 The section of the feasibility report 

that explains the methodology for shoreline damage assessment is summarized in 

this manual as "Appendix D, An Example of the Use of Monte Carlo Analysis." 

13 U. S. Army Engin~er District Wilmington, West Onslow Beach and New 

River Inlet. North Carolina (Topsail Beach) Hurricane Protection and Beach 

Erosion Control Feasibility Report, (Wilmington, NC: CESAW, 1990). 

121 
STEP NINE: CALCUIATE DAMAGE-FREQUENCY RElATIONSHIPS 

The damage~frequency relationship relates damage associated with a given 

event to the frequency of that event. The relationship is represented by the 

probability that could be associated with any level of flood damage (e.g., 

damages of $5 million for a given location may be exceeded once every 10 

years, expressed as an exceedance probability of 0.1). As explained for 

riverine flood damages in the NED Procedures Manual - Urban Flood Damage, the 

stage-damage relationship (calculated by the economist) is combined with the 

stage-frequency curve (calculated by the hydraulic and hydrologic engineer) to 

yield the damage-frequency relationship. 

In the coastal environment, however, flood damages occur as a result of 

a number of different, yet interrelated, causes. Structures become undermined 

and falloff into the ocean due to long-term erosion which occurs over a 

number of years, or during a single event as a result of storm recession. 

Structures become inundated as a result of storm surge, resulting in damage 

dUe to saturation of materials and hydrostatic pressures. Under certain 

conditions, wind-blown waves often add to these forces and destroy structures. 

Just as frequency relationships were constructed separately for various levels 

of long-term erosion, recession, inundation, and wave attack, damage-frequency 

relationships should also be calculated for each of the applicable damage 

mechanisms. However, because of the interdependency of these damage 

mechanisms it is important to avoid double-counting. This can occur when the 

sum of damages resulting from the individual damaging mechanisms exceeds the 

total damages actually incurred. The combined damage-frequency relationship 

should reflect the mechanism yielding the maximum damage or "critical damage" 

for a given return frequency. There is one damage-frequency relationship fo'r 

122 
e~ch unique set of beach ~rofiles, which can fluctuate from inundation to 

storm recession to wave attack for different frequency events. Furthermore, 

the analysis of cumulative damage for future years can vary as properties are 

removed from the damageable inventory and long-term erosion increases the 

landward limit of damage. 

TRADITIONAL TECHNIQUE 

By applying a frequency interval to each damage range, ~ weighted average for each of these events can be computed. For storm damage and erosion 

damage computations, the damage-frequency relationships may need to be 

computed for every five-year increment in the project life, or more often if 

changing erosion damage patterns warrant. 

The inundation damage procedure is the same as traditional flood damage 

prevention procedures except the damage curves must be changed each five to 

ten years as the long-term erosion process adds or removes property from the 

damageable inventory. 

MONTE CARLO TECHNIQUE 

For storm damage and erosion damage computations, the damage curves 

should be computed for every unique erosion-damage and beach profile pattern 

in the same manner as the traditional approach. This does not imply that 

damage-frequency relationships must be developed for every foot or five feet 

of erosion, but rather for the points where there is a ma,jor change inthe 

shape or magnitude of the damage relationships, such as when bulkheads are 

breached, the natural beach is gone, a spit is. breached, or other similar 

major changes in profiles are noted. 

123 
The damage relationships are used by the simulation models to calculate 

damages from randomly generated storms. As many sets of relationships as 

needed to adequately describe the range of possible conditions should be 

generated. The.model will interpolate. between the curves and points on a 

curve to determine the actual predicted damage for a generated storm and 

existing beach profile. The significant difference is that a procedure is 

developed for the computer to select storms in a random sequence and to 

calculate damages as they occur for each game. 

EXAMPLE 

In the New Jersey stud:y, frequency relationships were evaluated independently for each of the mechanisms responsible for structural damages: longterm erosion, inundation, recession, and wave action. These evaluations are 

described in Step Four above, "Establish Frequency Relationships." Likewise, 

damage-frequency relationships wet;'e also developed for each of the damaging 

mechanisms. 

Based on the historical long-term erosion rate of three feet per year, 

the area exposed to long-term erosion was determined for ten year increments 

over the 50-year project life. As previously mentioned in Step Four above, no 

long-term erosion was considered beyond the seawalls and roadways paralleling 

the beach because these structures would be protected through human interve~­

tion. In determining damages, undermined structures were considered a total 

loss and would not be rebuilt. The value of each structure impacted by longterm erosion was.removed from the evaluation when considering storm-induced 

damages in subsequent years. 

124 
Unlike long-term erosion which is assumed to halt at the seawalls and 

major access roads, storm recession occurs over a short period during the 

course of a major storm, thereby preventing human interruption and thus may 

include any structures including those protected by the seawall. In areas 

protected by the seawall or bulkheads, the recession is temporarily halted 

until frequencies significant enough to cause wall failure are reached. Once 

this occurs, recession takes place beyond the protective structure. The 

frequencies at which the seawall and bulkheads were anticipated to fail for 

each planning reach are presented in "Appendix B, An Example of NED Economic 

Benefits Analysis." The potential damage to any structure from storm recession was determined based on the structure replacement value, content value, 

lost income, and emergency costs as determined from sample interviews. Damage 

was assumed to begin when the recession distances exceeded the leading edge of 

the structure as defined by the setback distance with total damage occurring 

when recession reached the midpoint of the structure. Damage between these 

two points was determined using linear interpolation. 

For inundation damages, generalized damage functions were generated from 

on-site investigations of the sample population. These functions reflected 

anticipated damage as a percent of building size for one foot increments of 

depth related to the structure's main floor. These were integrated with 

stage-frequency data (developed by CERC) to permit the calculation of damages 

due to inundation associated with a specific return period. The stagefrequency curve used for determination of ocean-related flood depths included 

the influence of wave setup. 

Flooding could also result from the possibility of severe waves 

overtopping the protective seawalls and inundating the area landward of the 

125 
seawall. However, overtopping rates and depths of flooding vary widely, even 

for storms with similar recurrence intervals due to various storm parameters. 

The analysis therefore developed depth-frequency curves directly from known 

historic flood marks, flood marks collected during damage interviews, and 

frequency data for the Sandy Hook gauge provided by the NOAA Tidal Records 

Section. The upper limit of the overtopping analysis was the frequency at 

which the seawall loses its structural integrity; at this point it was assumed 

there would be direct flooding from the ocean. 

For wave attack damages resulting from direct wave impact on structures, 

the population subject to wave forces was defined. Analysis indicated a wave 

height of slightly more than three feet was necessary to cause structural 

failure. (This height was used primarily to depict the potential wave attack 

population, not to determine structural failure.) The areas subject to 

breaking waves of this height, or wave zones, were delineated for storms with 

return periods of 25, 100, and 500 years. Specific structures exposed to wave 

attack were identified. The actual depth necessary for structural failure was 

calculated for wood frame, masonry, pile-supported, and pile- and piersupported structures. This process is described in greater detail in 

"Appendix B, An Example of NED Economic Benefits Analysis." 

To move toward average annual damage calculations, damages for each 

reach were sununarized by frequency-damage over the 50:"year life of the 

project .. This procedure was designed to eliminate the potential for double 

counting. Each one-foot stage of inundation was related to a frequency and 

that frequency was used to evaluate the potential damage from e'achdamage 

mechanism. To prevent double counting (the sum of damages resu1tingfrom the 

individual damaging mechanisms will far exceed the actual damage suffered), 

126 
only the maximum damage to any single structure was reported for a. specific 

frequency. As depicted in Figure 0-8 in Appendix B, the critical damage can 

fluctuate from inundation to storm recession to wave attack for different I 

frequency events. For display purposes. the damage associated with the 

individual mechanisms are based on a percentage of their summed total 

corrected to restated critical damage. Furthermore, the analysis of 

cumulative damage by reach for future years can vary as segments of the 

population are removed from the data base and long-term erosion increases the 

landward limit of damage. To account for changing future conditions, the 

critical damage at each year and frequency was multiplied by the probability 

that the structure exists and is subject to damage at that frequency event. 

The probability of existence for each structure was calculated using the 

maximum probability of total damage from wave attack or storm recession for 

each year analyzed with straight line interpolation for the intervening years. 

To provide a comparison to historic storm surge and damage data, the 

existing condition critical damage for various frequency events was aggregated 

into a still water ocean stage versus damage relationship. Although damage is 

presented in relation to stage to permit a comparison to historic storms, it 

should be noted that the damage associated with wave attack and recession was 

evaluated for the various storm frequencies and, thus, stage has merely been 

used as a surrogate for display purposes. The stage versus d&mage comparison 

developed using this methodology for 1985 existing conditions is presented in 

Table 0-9 of Appendix B. Comparison of the predicted damages to the historic 

damage indicates concurrence with a March 1984 storm. The differences between 

damages reported for a 1962 storm and those predicted for 1985 appear 

reasonable, considering the impacts of over 20 years of shoreline erosion, 

127 
intensive development, increases in real estate value, and seawall 

degradation. 

STEP TEN: CALCUlATE EXPECTED ANNUAL DAMAGES 

The expected annual damage is the expected value of erosion losses and 

storm damages in any given year. Calculation of expected annual damages, does 

not mean that this amount of damage will occur in any particular year, but it 

is rather the actuarial value of the damage risk. Over a long period of time, 

the average amount of damage will tend to approach that value. Expected 

annual damages are the most tangible measure of the severity of the existing 

erosion and/or storm damage problem. If there is long~term erosion, expected 

annual damages will increase each year. 

TRADITIONAL TECHNIQUE 

Erosion damage is separated from inundation damage in an attempt to 

avoid double counting benefits. Losses due to erosion should be calculated 

for each year. A family of damage curves will be needed. As erosion progresses, damage from a given event will have greater or lesser impact than its 

predecessor of equal intensity. The reason is that the shoreline has changed 

due to the prior events and hence the inventory of damageable property and 

damage susceptibility of the remaining property will have changed. This will 

result in several damage estimates for each event: damage resulting from the 

long-term changes in shoreline (long-term erosion), storm-related recession, 

storm-relat,ed inundation, and storm-related wave. attack. 

Expected annual damages are calculated by computing the area under the 

storm-related and inundation damage-frequency curves, and adding to that the 

128 
effect of long-term shoreline changes. This is done mathematically by 'taking 

an integral of the function. Integration can be approximated by graphically 

measuring the area under the damage-frequency curve or by other non-mathematical means. Normally, a funetion is not computed. Several points which reasonably define the curve are computed, and any other points needed for calculations are approximated by interpolating between those points previously 

determined. A sample computation of this procedure is provided in the NiQ 

Procedures Manual - Urban Flood Damage. Expected values computed for 

frequencies in Step Nine are weighted by their exceedance probability. In 

most damage areas, the high frequency events usually account for the major 

share of the average annual damages. 

MONTE CARLO TECHNIQUE 

In contrast to the analytical method, this method calculates the 

expected annual damages by using a very large (usually 100 or more) number of 

trials or games, which are then averaged to produce the expected annual 

damages as well as other pertinent statistics. 

The analyst first describes the study area in terms of property location, value, damage susceptibility, and beach profile. Storm events, erosion, 

and/or accretion are described in terms of frequency (how many significant 

events can happen in any season as well as probabilities for each level of 

event), and intensity. The model selects a possible event from those described by the modeler, calculates the damage (if any), logs the ending beach 

profile, and then proceeds to the next time period to repeat the process. As 

the beach profile changes, the model will calculate damages by interpolating 

between the appropriate damage curves. 

129 
The tiDle period sele.cted .can be weeks or months. The modeler must 

des.cribe how to distinguish be.tween bea.ch build-up seasons and erosion 

seasons. A signifi.cant advantage of this methodology is that, similar to real 

world .conditions, events in one period determine the base .condition for the 

next, and Dlultiple events are possible in a given year. This situation is 

more realisti.c than having relatively stati.c beginning .conditions in every 

period or basing the beginning .conditions on an average .change over time. 

EXAMPLE 

In the New Jersey study, the .criti.cal damage-frequency relationships 

(described in Step Nine above), including adjustments for probability of 

structure existence, were used to compute average annual damages at ten year 

increments for the 50-year proj ec.t life using the Hydrologic Engineering 

Center (HEC) computer program "Expected Annual Damages" (EAO). Average annual 

residential damage for physical, emergency, and lost income damage and 

increased residential contents damage (resulting from the affluence factor) 

were calculated for each reach. Total average annual flood damages (including 

physical, emergency, and lost income damages to structures, damages to 

seawalls, damages to roads and infrastructure, and public emergency costs) 

were also determined for all reaches in the study area. These were calculated 

for existing conditions as well as conditions expected during the project life 

(1990-2040). The methodology for estimating future conditions accounted for 

rebuilding of existing structures and future increases in the value of 

residential contents .. Tables summarizing average annual residential damages 

(Tables 0-10 and 0-11) and total without project average annual damages (Table 

0-12) are presented in "Appendix B, An Example of NED Economic Benefits Analysis.' 

130 
STEP ELEVEN: ESTIMATE STORK DAMAGE REDUCTION AND EROSION PREvENTION BENEFITS 

The reduction in expected annual damage and/or long-term erosion damages 

that may result from implementation of a particular plan are the NED storm 

damage reduction and/or long-term erosion benefits. The NED benefits are used 

in plan formulation and evaluation. They are used to identify economically 

feasible alternatives, to determine the optimum scale of alternative plans, 

and to identify the NED plan. 

The NED storm damage reduction and/or long-term erosion reduction 

benefit calculation is the difference between expected annual damages 

determined in Steps One through Ten under the without-plan conditions and the 

expected annual damages estimated in Steps Seven through Ten under the withplan conditions. All benefit estimates should be made for existing conditions 

(those existing at the time of the study), the base year (the first year in 

which the project is expected to become operational), and future conditions 

over the period of analysis. This period, usually 50 years, is defined as the 

time horizon, beginning with the base year, for which project benefits and 

operation, maintenance, and replacement costs are considered. The discounting 

procedures described in "Chapter XI, Discounting Procedures" of the NED 

Procedures Manual - Urban Flood Damage should then be used to derive estimates 

of average annual equivalent benefits. 

EXAMPLE 

Storm Damage Reduction Benefits. In the New Jersey study, storm 

reduction benefits were calculated for each of the 14 economic reaches. Storm 

reduction benefits from the proposed plans of improvement were estimated by 

evaluating damages with- and without-project and under existing and future 

131 
conditions. The storm reduction benefits derived from the proposed project 

consisted of preventable average annual damages to buildings, roads, 

utilitieS, and other structures; reduced public emergency costs; and reduced 

maintenance costs. 

Benefits were based on damage to existing development. Changes in 

future floodplain development considered in the analysis were limited to 

constraints on structure rebuilding and. increased residential content damage 

due to expected increases in homeowners' affluence. Storm reduction benefits 

were derived from the computation of average annual flood damages resulting 

from the maximum damage occurring for a specific return period when 

considering inundation, wave attack, and storm recession. The benefit 

analysis conducted over the 50-year project life reflected a reduction in 

structure population due to long-term erosion. Damage to the seawall was 

based on failure of the seawall due to a combination of recession and storm 

attack causing displacement of the stone. Once 45 percent of the stone was 

displaced, the wall was considered to be effectively lost. Because the State 

of New Jersey already expends $5.41 to $18.98 per linear foot on annual 

maintenance of the seawall, reduced seawall maintenance costs upon 

implementation of a with-project alternative were also counted as benefits. 

Damage to roads and infrastructures was calculated based on storm recession 

undermining the facility, necessitating replacement and emergency bypassing. 

Breakdowns of storm damage reduction benefits to buildings, infrastructure 

facilities, seawalls, and reduced seawall maintenance costs for alternative 

plans of improvement and various berm widths are presented in Tables D-13 

through 0-15 in "Appendix B, An Example of NED Economic Benefits Analysis." 

132 
Erosion Prevention Benefits. The Sea Bright to Ocean Township project 

area is subject to a loss of land due to long-term erosion. Therefore, the 

value of this land represents a separate category of potential project 

benefits as long as erosion will be halted or reduced by project 

implementation. According to analysis performed for the study, the 

nourishment program would prevent future losses of property to long-term 

erosion. To quantify land loss damages, the acreage subject to erosion was 

identified. This was accomplished by initially obtaining the ocean frontage 

for each reach and then applying the long-term historic erosion rate of three 

feet per year. Long-term erosion was assumed to be halted at the leading edge 

of seawalls and road system paralleling the beach, based on antiCipated 

intervention by man. Review of existing land development and shoreline 

protective. measures indicated that loss of developed land was limited to just 

three of the 14 reaches; land loss in other reaches consisted primarily of 

beach area and recreation lands. For each of the reaches with developed land, 

land values (representative of nearshore land) were established by gross value 

estimates and then applied to the potential acreage lost per year for the 50-

year project life. These values were brought to present worth and their sum 

amortized over the life of the project (using an 8-5/8 percent interest rate), 

yielding an average overall damage for eroded land. Since, under with-project 

conditions, long-term erosion will be halted by annual nourishment, this 

figure represents the average annual benefit associated with lost land. 

Benefits from Reduction of Public Damages. Another category of benefit 

from the proposed plans of improvement at Sea Bright to Ocean Township is the 

reduced requirement for beach fill maintenance at the Sandy Hook unit of the 

Gateway National Park. The Sandy Hook seashore, located just updrift of the 

133 
project limit, is a severe erosion area subject to washovers and breaching. 

Construction of the proposed beach fill project would eliminate this erosion 

and result in a reduction in beach fill maintenance cost to the National Park 

Service. The reduction in maintenance cost was included as a project benefit. 

Other Benefits. Other benefits resulting from the proposed storm damage 

reduction and erosion control project, such as recreational benefits, were 

identified in the New Jersey study. Procedures for estimating recreation 

benefits are outlined in NED Procedures Manual - Recreation. Volumes I and II. 

Summary of Benefits. Using the procedures summarized above, benefits 

associated with alternative berm widths of 50 feet, 100 feet, and 150 feet 

were evaluated for three plans: pure beach fill, beach fill with authorized 

groins, and beach fill with updated groins. Analysis indicated that a fillonly plan at a width of 100 feet provided the maximum net benefits. In order 

to further maximize storm protection at the least cost,the benefits 

associated with increasing the level of protection above the 10-foot MLW 

authorized berm height were evaluated. Assessment of berm caps of 0 feet, two 

feet, and four feet, based on the reduced probability of residual damages 

occurring, indicated that maximum net benefits are obtained with a two-foot 

berm cap. 

134 
CHAPTER. V 

DOCUMENTATION 

PLANNING REPORTS 

As noted in Chapter I, the concepts and procedures described in this 

manual are primarily used in implementation and other plan formulation and 

evaluation studies. The results. and findings of such studies are usually 

documented in planning study reports. Basic standards for the organization, 

format, and content of such reports are established in ER1105-2-100, Chapter 

2, Section II. Flexibility of presentation is provided,. however, for studies 

of varying scope, complexity, and subject .matter. The main objectives of the 

planning reports, as presented in ER 1105-2-100, are to insure adequate 

presentation of study results and findings, to insure compliance with 

applicable statutes and policies, and to provide a sound basis for decisionmakers on recommended solutions to water resources problems. 

TYPES OF REPORTS 

Generally, two categpries of planning reports may pe produced: 

feasibility or reevaluation reports. Feasibility reports, for which an NED 

storm damage and long term erosion analysis may be appropriate, include 

Reconnaissance Phase Reports, Feasibility Phase Reports, Legislative Phase I 

General Design Memoranda, and Section 903 Repo~ts.l Other feasibility 

reports include reconnaissance, feasibility and detailed project reports 

1 Section 903 Reports cover the 62 projects authorized for construction 

in the Water Resources Development Act of 1986 that are subject to Section 

903(a) of that Act. The format for these reports and the list of projects to 

which Section 903 applies are provided in ER 1105-2-100, Appendix D, Section 

I. 

135 
completed under the Continuing Authority Program such as Section 103, Section 

111 and Section 14 Reports. Reevaluation reports represent those resulting 

from preconstruction planning and engineering studies. 

FEASIBILITY REPORTS 

Each feasibility report documents the logic of the plan formulation 

process. As such, it needs to be a complete, but concise, decision-making 

document. On studies of broad scope and complexity, the report may include a 

concise summary of plan formulation, in which case detailed plan formulation 

may be contained in an appendix. Additional appendices may be used as 

necessary when the information represents an integral part of the report but 

their contents cannot be accommodated in the main report volume. Other 

technical details should be presented in supporting documentation. 2 

The feasibility report should state the study authority, the study 

purpose and scope, and briefly discuss prior studies, reports, and existing 

water projects, if applicable. A plan formulation chapter should summarize 

the extent of the storm damage and/or erosion problem, including the existing 

and future without-project conditions, problems, and opportunities that 

influence the evaluation. The evaluation should also address planning 

- constraints, alternative solutions to the problem, and the rationale for 

selection of a recommended action or a no-project alternative. 

2 According to ER 1105-2-100, the following supporting documentation 

shall be prepared and reproduced separately from the feasibility report and 

appendices for technical. review .of feasibility studies: engineering design 

data that supplement the plan formulation and the plan selection process; 

detailed economic data and any derivations from that .data that. support plan 

formulation, forecasts, or benefits; supplemental environmental material 

required by the applicable environmental protection statutes; any other 

specific subject matter of unique or complex nature necessary to support 

planning; and the project management plan. 

136 
A description of the recommended plan should include plan components, 

including mitigation; design and construction considerations; operation and 

maintenance considerations; plan accomplishments; and, a summary of economic, 

environmental, and other social effects. The benefits of the recommended 

plan, the NED plan (if different from the recommended plan), and any other 

plan carried through the planning process should be well documented. The 

benefits of each plan should be displayed in current dollars for existing 

conditions, and for conditions expected during the base year and in 

appropriate increments through 50 years beyond the base year (or for the 

duration of the project's economic life). Benefits for all years beyond the 

base year should be discounted by the administratively established discount 

rate. 

Other required components of the feasibility report are an 

implementation plan, including institutional requirements, division of Federal 

responsibilities and local cooperation requirements, and the views of nonFederal sponsors and other agencies having implementation responsibilities; a 

summary of coordination, public views, and comments; and, the official report 

recommendations from the District Engineer. For greater detail on the format 

and content requirements of each section of the feasibility report, see ER 

1105-2-100, Chapter 2. 

Final feasibility reports that recommend no Federal action or plan 

authorization shall be organized generally in the same manner as those 

recommending Federal action. However, such reports may be abbreviated to the 

essential information needed to support the recommendation, consistent with 

the level of study and analysis made in arriving at the findings. 

137 
REEVAIlJATION REPORTS 

Preconstruction planning and engineering studies which recommend postauthorization changes by Congress are considered feasibility type reports (see 

ER 1105-2-100, Chapter 2). They should be organized, to the extent 

appropriate, in the same manner as feasibility reports. More flexibility is 

allowed for those reevaluation studies which do not seek Congressional postauthorization approval, in which case they should be organized and detailed at 

a level commensurate with their findings. 

SUPPORTING DOCUMENTATION 

Supporting documentation, which is prepared and reproduced separately, 

augments the feasibility or reevaluation reports with more detailed data and 

analysis. It is not intended to be read alone, but rather with the main 

volume of the planning report. Support documentation includes engineering, 

design, cost, economics, and environmental material. The economics material 

should contain details of any forecasting analysis and of the derivation of 

the economic data for plan formulation. It shall also include a detailed 

explanation of the benefits for each plan included in the report it 

supplements. Specific elements to be addressed in supporting documentation, 

when applicable, include predicted erosion rates, structural damages by damage 

categories, and historic and projected storm conditions. All assumptions 

should be explicitly documented. 

138 
DETAIL AND DISPLAY 

DETAIL 

The amount of detail required in a report is a variable governed 

primarily by 'the objective of full support of the essential analyses and 

conclusions of the study. Clarity in the report enables reviewers to 

understand the rationale for the conclusions and recommendations. Since the 

report requires input from many different technical specialists, extensive 

coordination is required to insure a consistent and logical presentation. 

Reconnaissance level design and other technical features need only be adequate 

to establish general technical feasibility and an adequate, but approximate, 

sizing and costing of plan features. 

DISPLAYS 

Visual displays, such as maps, tables, graphs, and photographs, 

represent a very useful and often essential means ~f presenting a variety of 

information that would be too cumbersome or complex to present in textual 

form. Furthermore, they are indispensable in the presentation of the complex 

physical and economic relationships described throughout the planning report. 

For example, maps are necessary to illustrate the study area, existing 

conditions, and future with- and without-project conditions; tables are 

necessary for hydrologic and economic data and cost and benefit comparisons; 

graphs present an effective means of plotting trends in tabular data; and 

figures are useful in displaying alternative solutions and the logic and 

decision-making process that led to the study recommendations. Producing 

graphics is made relatively simple and inexpensive by the present availability 

of computer-based software. 

139 
APPENDIX A 

COASTAL STORK DAMAGE AND BEACH EROSION CONTROL POLICIES AND AUTHORITIES 

143 
APPENDIX A 

COASTAL STORK DAMAGE AND BEACH EROSION CONTROL POLICIES AND AUTHORITIES 

AUTHORITIES 

Until 1930, the Federal interest in shoreline erosion problems was 

limited to the protection of Federal property and improvements for navigation. 

The following laws summarize the Corps role in shore protection as mandated by 

Congress. 

Public Law 71-520. River and Harbor Act of 1930. This law established the 

Beach Erosion Board to act as a central agency to assemble data and provide 

engineering expertise regarding coastal protection. At the request of cities, 

counties, or states, the board was authorized to study effective means of 

preventing erosion of coastal and Great Lakes shorelines. The Federal 

government could share up to half the cost of each study but could not commit 

construction money unless Federally-owned property was involved. 

Public Law 79-526. Flood Control Act of 1946. This Act authorized the 

Secretary of the Army to undertake emergency bank-protection measures to 

prevent flood damages to endangered highways, public works, and non-profit 

public facilities. 

Public Law 79-727. 1946. This law authorized the Federal government to assist 

in the construction, but not the maintenance, of civil works projects to 

protect publicly-owned shorelines against erosion from waves and currents. 

145 
Public Law 84-71. 1955. This law authorized the Corps, in conjunction with 

other Federal agencies, to assemble data on the behavior and frequency of 

hurricanes along the U.S. ·At1antic and Gulf coasts and to determine means of 

preventing loss of life and damages to property. This Act does not specify 

any cost sharing for construction of protective works. 

Public Law 84-99. 1955. This legislation authorized the Corps to provide 

emergency protection to threatened Federally authorized and constructed 

hurricane and shore protection works, and to repair or restore such works 

damaged by wind, wave, or water action of other than an ordinary nature. 

Public Law 84-826. 1956. This legislation authorized Federal participation in 

the protection of private property if the action was incidental to the 

protection of public lands or it would result in public benefits. The law 

also allowed Federal assistance for periodic beach nourishment on the same 

basis as new construction, for a period to be specified by the Chief of 

Engineers, when that alternative was the most suitable and economical remedial 

measure. 

Public Law 85-500. 1958. Three hurricane flood protection projects were 

authorized under this Act. Local cooperation provisions were mandated: nonFederal interests were required to assume 30 percent of the total first costs, 

including the value of lands, easements, and rights-of-way, and to operate and 

maintain the projects. 

146 
Public Law 87-874. The Riyer and Harbor Agt of 1962. This sweeping 

legislation significantly expanded the Corps role in shoreline erosion, 

including authorizing the Secretary of .the Army to reimburse local interests 

for beach erosion.work already performed; making the cost of studies a Federal 

responsibility; increasing the Federal share of construction costs; giving 

authority to the ASA(CW) for planning and constructing small beach erosion 

control projects (Section 103 projects) within certain monetary limits without 

specific Congressional authorization; and introducing the multiple-purpose 

concept of erosion control, hurricane protection, and related purposes in 

shoreline studies. 

Publig Law 88-172. 1963. This law abolished the Beach Erosion Board and 

created the Coastal Engineering Research Center (CERC) within the Corps of 

Engineer~. The review functions formerly performed by the Beach Erosion Board 

were transferred to the Board of Engineers for Rivers and Harbors. The 

Coastal Engineering Research Board was also established as an advisory group 

to the Chief of Engineers. 

Public Law 89-72. The Federal Water Projegt Recreation Act of 1965. This Act 

required that planning of water resources projects consider opportunities for 

outdoor recreation and fish and wildlife enhancement. It specified that the 

outdoor recreation benefits that can be attributed to a project shall be taken 

into account in determining the overall benefits of the project. For ,example, 

the recreational use of beach fill, groins, or other protective structures 

shall be considered during plan formulation. 

147 
Public Law 89-298. 1965. This legislative action allowed Federal 

contributions toward periodic beach nourishment. 

Public Law 90-483. 1968. Section 111 of this law authorized the Corps to 

study, plan, and implement structural and non-structural measures for the 

mitigation of shore damages attributable to Federal navigation works. This 

authority applies to both public and privately-owned shores along the coastal 

and Great Lakes shorelines. 

Public Law 92-583. The Coastal Zone Management Act of 1972. This Act required 

all Federal agencies with activities directly affecting the coastal zone, or 

with development projects within that zone, to assure that those activities or 

projects are consistent with the approved state program. 

Public Law 93-251. 1974. Section 27 of this law raised the cost limits for 

emergency bank protection projects and extended project purpose to cover 

construction, repair, restoration, and modification of emergency streambank 

and shoreline protection works. Section 55 authorized a shoreline and 

streambank erosion control demonstration program and approved technical and 

engineering assistance to non-Federal public interests for developing 

structural and non-structural methods of preventing damages attributable to 

shore and streambank erosion. 

Public Law 94-587. 1976. Provisions of this legislation included authorizing 

the Corps to place beach-quality sand obtained from construction and 

maintenan~e of navigation inlets onto adjacent beaches if: 1) requested by 

148 
the interested state government. and 2) local interests agreed to pay 100 

percent of any increased costs above the cost required for alternative methods 

of sand disposal (e.g .• open water disposal). Section 156 extended Federal 

participation in periodic beach nourishment up to 15 years from the initiation 

of construction. 

PubliC Law 97-348. 1982. This law established the policy that coastal barrier. 

islands are to be protected by restricting Federal expenditures which 

encourage development on those islands. The Act also identified undeveloped 

coastal barrier islands within which Federal expenditures may not be made. 

Public Law 99-662. Water Resourses Development Act of 1986. This legislation 

made several significant changes to cost sharing for shoreline protection 

projects. Non-Federal local sponsors were required to provide a minimum 35 

percent and maximum 50 percent contribution to the cost of construction of 

shore protection measures. The costs were to be assigned to "appropriate" 

project purposes (flood control. non-structural flood control. and hurricane 

and storm damage reduction. recreation. and others). with cost sharing in the. 

same percentage as the purposes to which the costs were assigned. Two 

exceptions were allowed. In the case of costs assigned to the prevention of 

losses of private lands (where the use of such lands is limited to private 

interests) the costs were to be non-Federal, while in the case of Federallyowned shores, all costs were to be Federal. One hundred percent of the costs 

of operation and maintenance of shore protection measures would be borne by 

non-Federal interests. Non-Federal interests would also provide all lands, 

149 
easements, rights-of-way, relocations, and disposal areas (LERRO); these costs 

could be credited to the non-Federal share of the project cost. 

The Act also exte~ded the period of beach nourishment from 15 to 50 

years. It authorized, for environmental or economic reasons, the use of nondomestic sources of fill material for beach erosion and nourishment projects 

if such material was not available from domestic sources. Section 933 of the 

Act authorized increasing to 50 percent the Federal share of the additional 

costs, above that required for alternative methods of disposal, for placement 

of material dredged during the construction and maintenance of navigation 

inlets onto adjacent beaches. Implementation of non-structural measures to_-

prevent or mitigate shore damage attributable to Federal navigation projects 

was also authorized, with the costs of prevention or mitigation measures to be 

shared in the same proportion as the cost sharing provisions of the navigation 

project. Finally, Congressional authorization was required for all projects 

costing in excess of $2 million. 

Public Law 100-676. Water Resources Development Act of 1988. Section 14 of 

this Act requires non-Federal interests to agree to participate in and comply 

with applicable Federal flood plain management and flood insurance programs 

before construction of any hurricane .and storm damage reduction proj ect. 

SUMMARY OF POLICIES 

Current Corps policy on shore protection is stipulated in EP 1165-2-1, 

Digest of Water Refources Policies and Authorities. Significant excerpts from 

the pamphlet are provided below. 

150 
EROSION CONTROL 

Under existing shore protection laws Congress has authorized Federal 

participation in the cost of measures to prevent or control shore erosion, and 

reduce damage to upland developments caused by wind- and tidal-generated waves 

and currents along the nation's coasts and sho,res, the Great Lakes, and their 

associated lakes, estuaries, and bays. The shore erosion must be caused by 

wind and tidal generated waves; therefore, the authorization does not cover 

erosion at upstream locations caused by stream flows except for those actions 

defined as emergency measures to protect highways,. public works, and nonprofit public facilities. Federal participation is limited to restoration of 

. . the historic shoreline. Any extension of the shoreline beyond the historic 

shoreline will be at the expense of non-Federal interests. 

Costs for measures for the prevention of land losses are assigned to 

either Federal or non-Federal interests depending upon shore ownership. Costs 

assigned to protection of Federally-owned lands and shores are 100 percent 

Federal. The cost for shore protection for lands controlled by another 

Federal agency (for example, military installations and Nation;al Park Service 

lands) will be borne by that agency. The Corps will accomplish such work on a 

reimbursable basis upon request. One exception is a case in which the lands 

in question involve only a minor, but integral, part of the overall protection 

frontage. In such cases, protection will be included to assure a complete 

overall project. 

The costs to protect undeveloped private lands or devel()p~d private" 

J 

lands where the use of the shore is limited to private interests are allocated 

151 
wholly to non-Federal interests. Costs assigned to prevention of damage to 

privately-owned lands that meet criteria for public use are 35 percent nonFederal. The costs are split 50/50 between Federal and .non-Federal interests 

for those non-Federal public lands and shores used for parks and recreation or 

fish and wildlife purposes. Where a shore protection project encompasses 

more than one category .of oWnership and use, the non~Federal share of project 

costs will Qrdinaril, be e~pressed as a composite percentage of total project 

costs derived 'by weighting the appropriajte cost sharing percentages for the 

given categories by the lim~ar feet of project shoreline within those 

categories. This is where the initial construction costs are reasonably 

unifot:m for the entire project; where they are not, the project shoreline will 

be first subdivided into segments that are relatively uniform in costs and a 

weighted percentage calculated from the total costs, from all segments, 

assigned to each category.l 

No Federal contribution toward maintenance of a shore protection project 

is authorized. However. PL 84-826 allows Federal participation in periodic 

beach nourishment when it is found to comprise a more suitable and economical 

remedial measure for shore prQtection than retaining structures such as 

groins. Periodic nourishment is.to be considered "construction" for funding 

and cost sharing ~urposes, and is limi~ed to the period specified in the 

authorizing legislation. 'The Water Resources Development Act of 1986 (WRDA 

86) allows el(tension of the authorized period to 50 years from the date of 

initiation of construction, i.:f appropriate .. 

1 A practical example of the ~ost sharing computations required for a 

hurricane and storm damage reduction project having mixed Federal, nonFederal, and private ownership is illustrated in ER 1165-2-130, Appendix C. 

152 
HURRICANE AND STORM DAMAGE REDUCTION 

Befora enactment of theWRDA 86, Faderal projects to protect against 

hurricane and abnormal tide flooding were established case-by-case based on 

specific Congressional authorizations. Although such project works were 

usually similar to beach erosion control works, hurricane protection projects 

were viewed as being more like flood control projects. ' The 1986 Act, however, 

authorizad Federal participation in hurricane and storm dama:ge reduction 

projects and established a cost sharing formula requiring 35 percent of the 

construction costs to be borne by the non-Federal partner. Other than the 

magnitude of storms considered, there are now no real distinctions between 

shore protection measures for hurricane, storm-, or tidal-induced flooding and 

erosion. 

RECREATION 

Shore protection projects are to be formulated first to provide for 

hurricane and storm damage reduction. Although shore protection projects are 

usually conducive to beach and shoreline recreation activities, any 

enhancement of recreation associated with the project is considered 

incidental. P:rovided that the sum of storm damage reduction benefits and 

incidentally-generated recreation benefits (which are limited to an amount 

equal to or less than the storm damage reduction benefits) is sufficient~ for 

economic justification, the Corps would propose undertaking the project as a 

storm damage reduction project. All recreation benefits would be included in 

computation of the overall benefit-cost ratio. Additional beach fill beyond 

that needed to achieve the storm damage reduction purp6se to satisfy 

153 
recreation demand would be a separable recreation feature requiring separable 

50/50 cost sharing. However, current Corps policy precludes participation in 

separable recreation measures at shore protection projects. 

Table A-I summarizes cost sharing policy by project purpose (Le., 

coastal erosion reduction or hurricane and storm damage reduction) and 

property ownership. 

TABLE A-I 

SHORE OWNERSHIP AND LEVELS OF FEDERAL PARTICIPATION 

Shore Ownership 

and Project Purpose 

Maximum Level of Federal Participation 

Construction 1 Maintenance 

I. Federally owned 

Hurricane & Storm Damage Reduction 

Loss of Land 

Recreation (Separable Costs) 2 

II. Publicly owned and/or privately 

owned with public benefits 

Hurricane & Storm Damage Reduction 

Loss of Land 

Recreation (Separable Costs) 2 

III. Privately owned. use limited to 

private interests 

Hurricane & Storm Damage Reduction 

Loss of Land 

Recreation 

100% 

100% 

100% 

65% 3 

50% 3 

50% 3 

none 

none 

none 

100% 

100% 

100% 

none 

none 

none 

none 

none 

none 

1 Where appropriate, periodic nourishment is considered "construction." 

2 Department of Army Policy precludes civil works funding of separable 

recreation measures at shore protection projects. 

3 The fair market value of lands, easements, rights-of-way, relocations, and 

disposal areas (LERRD) is included in these cost sharing percentages, 

unless the land has no value. 

154 
LAKE FLOOD PROTECTION 

The extent of Federal interest in projects to protect against lake 

flooding (e.g., the Great Lakes) is not explicitly defined by legislation. 

Congressional authorizations for Corps construction of such projects on a 

case-by-case basis are helping to establish the Federal interest. The WRDA of 

1986 authorized the Corps to undertake a cooperative study of shoreline 

protection and beach erosion control policy and related projects for the Great 

Lakes. This study will include recommendations for new or additional criteria 

for Federal participation in shoreline protection projects along the Great 

Lakes and connecting channels. 

155 
APPENDIX B 

AN UAHPLE OF NED ~CONOKIC BENEfiTS ANALYSIS 

157 
158 
TECHNICAL 

APPENDICES 

VOLUME II 

January 1989 

ATLANTIC COAST OF NEW JERSEY 

SANDY HOOK TO BARNEGAT INLET 

BEACH EROSION CONTROL PROJECT 

SECTION I - SEA BRIGHT TO 

OCEAN TOWNSHIP, NEW JERSEY 

GENERAL DESIGN MEMORANDUM 

159 . 
TABLE OF CONTENTS1 

Paragraph 

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§WQ~::A~"~ 

Subject 

....... ', .. '.'. :.:.:.' ... :.:::.:.:.:.:.:' ........ . 

,', ... ;:.::::;:::;::.:::: : .. :::~:: ... :.: ,', ,.,: . ,: . . 

1Excerpted portions included in this NED Procedures Manual are 

n;w#:M.iilj!!q. Page numbers refer to the pages within this manual. 

161 

I 

+m~: MlP': 

iJ.i.:?q: 

*",,: 
TABLE OF CONTENTS (Cont'd) 

Paragraph Subject 

RECREATION BENEFITS 

0108. Objectives of the Analysis 

0110. General Plan of the Analysis 

D11l. 

0117. 

0121. 

0123. 

0126. 

0127. 

0132. 

0135. 

0140. 

0142. 

0146. 

0149. 

0152. 

0154. 

0155. 

0156. 

0163. 

Description of the Study Area 

Actual and Potential User Populations 

Beach Attendance, Summer 1985 

Concepts in the Use of CVM for NED Benefits 

Introduction 

Questionnaire Design 

Sample Design 

Construction of Sample Design 

Completion Rate 

Evaluation of Sample 

Analysis of Sample CVM Data 

Data Editing and Cleaning 

Application of the CVM to Beach Restoration 

Atlantic Coast of New Jersey 

Bid Functions 

With-Project Daily Pass Bid Functions 

Without-Project Bid Function for 

Respondents Using a Daily Pass 

Respondents Using a Season Pass 

Existence Value Bid Function 

Baseline Visitation Estimate 

Daily Pass Visitors 

Season Pass Visitors 

162 

Page 

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0164. 

0165. 

0174. 

0178. 

TABLE OF CONTENTS (Cont'd) 

Subject tage 

Existence Value 

Simulated Demand Curves 

Based on Bid Functions 

Confidence Intervals 

Summary of With- and Without Project Values 

BASELINE NED RECREATION BENEFITS 

FORECAST 

0182. 

0184. 

OF WITH AND WITHOUT PROJECT VISITATION 

Use Estimating Model (UEM) 

0186. 

Application of the UEM to the Northern New Jersey 

Beaches 

Forecast of Visitation to With- and Without;"'Project 

Beaches 

FORECAST OF NED BENEFITS 

0189. 1S0-Foot Berm 

0191. Summary of NED Recreation Benefits 

SEA LEVEL RISE 

SUMMARY OF 

0195. 

0197. 

0199. 

ECONOMICS 

0210. 

0211. 

0214: 

0215. 

BENEFITS 

Authorized Berm Height 

Adequacy for Storm Protection 

Analysis of Berm Cap Benefits 

OF THE RECOMMENDED 

Plan Description 

Benefits 

Sensitivity 

Residual Damage 

PLAN 

163 
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LIST 01" TABLES 

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pHf9~ 

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D-23 

D-24 

D-25 

D-26 

D-29 

D-30 

D-31 

LIST OF TABLES (Cont'd) 

Title 

$#'~h##~]ifq9@#ii@#'lij~jj~f.$#~.~8:1$~H~~#m!~m\l1ff9#~¥gf~#) 

~~III~II;~II~III~#~'~#@t4~:9f: ~~#m*~~~8lj Fi$+¥@#n 

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§B@#ii!¥¥;i¥F;~IM~#.9~9f#i+P@f~R~8ni 

Number of People Using the Beach 

Total Attendance 

Sample Design: The Projected Number of Interviews 

by Beach 

Sample Design: The Projected Number of Interviews 

by Questionnaire and Project 

Summary of Daily Pass Visitation 

Bid Function Simulate Demand 

With and Without Project Values 50' Project Berm 

Width 

Page 

~~:i!1: 

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(Rev. March 1990) 

165 
0-32 

0-33 

0-34 

0-35 

0-36 

0-37 

0-38 

0-39 

0-40 

0-41 

0-41A 

0-42 

0-43 

0-44 

0-45 

0-46 

0-46A 

0-46B 

0-47 

0-48 

LIST OP TABLES (Cont'd) 

Title 

with and Without Project Values 100' Project Berm 

Width 

With and Without Project Changes in Visitation 

With and Without Project Visitation Forecasts 

SO' Berm 

With and Without project Visitation Forecasts 

100' Berm 

Equivalent Annual NEO Recreation Benefits 

(April 1985 Price Levels) 

Equivalent Annual NEO Recreation Benefits 

(April 1987 Price Levels) 

Total Benefits - Fill Only 

Total Benefits - Beach Fill with Authorized Groins 

Total Benefits - Beach Fill Updated Groins 

Benefit and Cost Comparison 

Benefit and Cost Comparison - Oamage Reduction 

Benefits 

Berm Cap Benefits in Northern Sea Wall/Bulkhead 

Reaches 

Berm Cap Benefits in Southern Sea Wall/Bulkhead 

Reaches 

Berm Cap Benefits No Seawall or Bulkhead Reaches 

Total Benefits 

Berm Cap Analysis - Benefit Summary 

Incremental Benefits Summary Table 

Benefit and Cost Comparison - Incremental 

Construction of North & South Reaches 

Interest Rate Sensitivity - Costs Vs Benefits 

Residual - Oamage 100' Berm with 2' Cap 

166 

(Rev. March 1990) 
lItl 

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D-13 

D-14 

D-15 

D-16 

D-17 

D-18 

D-19 

D-20 

D-21 

D-22 

D-23 

D-24 

LIST OF FIGURES 

Title 

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Potential User Populations for Beach Restoration 

from Sea Bright Southward to Deal Lake 

outline of WTP Section of Survey 

outline of Benefit Categories 

Maximum Net Benefits - Fill Only Plan 

Maximum Net Benefits - Authorized Groin Plan 

Maximum Net Benefits - Updated Groin Plan 

Residual Damage with Berm Cap - Reach 3 

Damage Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

167 

&~:j: 

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LIST OF FIGURES (Cont'd) 

.!.2.:. Title 

D-25 Damage Limits - 100 Year Storm 

D-26 Damage Limits - 100 Year Storm 

D-27 Damage Limits - 100 Year Storm 

D-28 Damage, Limits - 100 Year Storm 

D-29 Damage 

D-30 Damage 

D-31 Damage 

D-32 Damage 

D-33 Damage 

D-34 Future 

Sub-Appendix D,-l 

Sub-Appendix D-2 

Sub-Appendix D-3 

Limits - 100 Year Storm 

Limits - 100 Year Storm 

Limits - 100 Year Storm 

Limits - 100 Year Storm 

Limits - 100 Year Storm 

Damage Limits - 100 Year Storm 

SUB-APPENDICES 

LAND APPRAISAL ATTACHMENT 

QUESTIONNAIRES 

SIMULATED DEMAND CURVES: BASED ON BID FUNCTION 

168 
Accretion: 

Berm: 

Erosion: 

Inundation: 

Recession: 

Runup:. 

Storm Surge: 

Variability: 

Wave Attack: 

Wave Setup: 

GLOSSARY.OFCOASTAL·TERMS 

Buildup of land or beach·· area 

Nearly horizontal part of the Beach 

Erosion and Long Term Erosion refer to the wearing 

away of land as measured over extended periods of 

time. Included are the impacts of sea level rise, 

deficits in sediment transport and the net impacts 

of storms, including post-storm accretion. 

Flooding from storm surges in the ocean and 

Shrewsbury River including wave setup and nooding 

from waves overtopping the seawall. (A still water 

effect since it does not laterally displace 

structures.) 

The reduction of land during a storm due to the 

transport of sediment. Includes the maximum area 

impacted by a storm before post-storm accretion. Net 

loss is accOunted for in long-term erosion. 

The rush of water up a structure or beach after the 

breaking of a wave. 

A rise in water level due to wind stress on the 

water surface and atmospheric pressure reduction. 

The variation in recession distance along the coast. 

The structural failure of buildings due to the force 

exerted by breaking waves or wave runup. 

Superelevation of the water surface over normal 

surge elevation due to onshore mass transport of the 

water by wave action alone. 

169 
APPENDIX D - BENEFITS 

INTRODUCTION 

Dl. Purpose. This Appendix evaluates the existing and future benefits 

which would accrue to the study area in light of current conditions and 

criteria. Investigations made and methodology used to evaluate the 

monetary value of existing and future benefits estimated to accrue as a 

result of implementing the proposed project are presented. 

D2. Benefits were calculated for alternative plans which meet the 

planning objectives and constraints as described in the main text. This 

preliminary screening identified three plans involving the placement of 

beach fill as addressing the region¥s problems and needs within reasonable technical and cost constraints. These plans are: 

1. Placement of beach fill 

2. Placement of beach fill with construction of the authorized 

groins, and 

3. Placement of beach fill with updated groins 

D3. Benefit Types. Benefits to be derived from the plan of improvement 

are: 

1. Reduction of damage associated with long-term and storm surge 

induced erosion including damage to roads, utilities and 

structures 

2. Reduction of wave attack to structures 

3. Reduction in inundation of structures 

4. Reduced maintenance costs for seawalls 

5. Reduced public emergency costs 

6. Reduced maintenance costs at Sandy Hook 

7. Reduction in lost land 

8. . Intensification 

9. Increased.recreation value 

D4. The first five benefit categories are storm reduction benefits. 

Figures D-l and D-2 provide schematic profiles displaying the location 

of without project damages and benefits claimed. 

D5. Conditions. Estimates of monetary benefits were based on June 1988 

price levels, a 50-year project life and reflect the economic condition 

of the flood plain as of July 1985. The base year for the proposed 

project is 1990. All calculations are displayed utilizing the fiscal 

year 1988 discount rate of 8-5/8%. Benefits at the fiscal year 1989 

discount rate of 8-7/8% are presented under Economics of the Recommended 

Plan. 

D6. Exclusions. Reduced Flood Insurance Administration costs have not 

been considered since the proj ect will not provide a total 100-year 

level of protection, which is the criterion for determining the need for 

Flood Insurance. Benefits due to reduced traffic delays have also not 

been included since even with the project in place, low lying portions 

of Route 36 which is the principal north-south corridor will be subject 

to flooding from the Shrewsbury River. 

171 
DESCRIPTION OF THE STUDY AREA 

07. Location. The Sea Bright to Ocean Township study area, shown on 

Figure 0-3, is located approximately 30 miles southeast of Newark, New 

Jersey, 40 miles east of Trenton, New Jersey and 6S miles northeast of 

Atlantic City, New Je~sey. The study includes the most northerly 12 

miles of the authorized project extending from just north of the Route 

36 Bridge in Sea Bright southward to the ,outlet of Deal Lake. The area 

encompassed by the study inclUdes the communities of Sea Bright, 

Monmouth Beach, Long Branch, Deal, Allenhurst and Loch Arbour (formerly 

a part of Ocean Township). The entire study area is within Monmouth 

County. Immediately to the north of'the project limit is the Sandy Hook 

unit of the Gateway National Recreation Area and immediately to the 

south is the City of Asbury Park. 

08. Mcnmouth County is accessible to major population centers through a 

network of modern highways. The Garden State Parkway runs northward to 

New York State and southward to Cape May. Route 18 extends westward to 

New Brunswick in Middlesex County and Route 195 extends westward to the 

state capitol in Trenton. Direct access from these major corridors to 

the ocean front is provided by various state and county roads including 

Route 36, Route 520 and Route 71. Communities from Long Branch southward are also serviced by the shore line of New Jersey Transit which 

provides passenger rail access to Newark and New York City. 

09. Natural Forces. The climate 'in' the study area is temperate with 

warm summers and moderate winters. The annual temperature averages 

approximately 53 degrees Fahrenheit (OF). On average January is the 

coolest month with a mean temperature of 32°F and July is the warmest 

month. The average annual precipitation is about 4S inches with August 

being the wettest month. Snowfall averages almost 25 inches annually .. 

010. The mean tidal range in the project area is 4.8 feet while the 

spring tidal range is 5.3 fee.t. Waves are predominately from the 

southeast with an average height of 1.5 feet. These conditions may vary 

extremely from normal due to both extratropical northeasters and 

hurricanes. 

011. Natural Resources. The northern portion of the study area from 

Sandy Hook south to Monmouth Beach, includes the communities of Sea 

Bright and the northern portion of Monmouth Beach and is comprised of a 

barrier spit complex where the shoreline is on a narrow strip of 

unconsolidated sand which forms a peninsula between the ocean and bay 

environments. The southern portion of the study area including the 

southern part of Monmouth Beach, Long Branch, Deal, Allenhurst and Loch 

Arbour is located on the Coastal Plain and is characterized by headlands 

meeting the sea. 

012. The entire coastal zone within the study area is heavily 

developed, primarily for residential and commercial uses. Many of the 

residences are former summer homes converted for year round use. In 

areas with substantial existing beach, such as near 7 Presidents Park in 

North Long Branch, the recent high rise and townhouse development 

indicates the desirability of protected beach front property. The 

172 
peninsula area is fronted by a seawall up to 20 feet in height or higher 

which aids in the prevention of flooding and wave attack. Traversing 

the peninsula area is State Road 36 which is the only major north south 

roadway linking the Highlands and Long Branch and provides the only 

access to Sea Bright and Sandy Hook. 

013. Prior to the construction of the Long Branch and Seashore Railroad, 

storms had repeatedly breached the barrier spit resulting in the formation of inlets that effectively joined the Shrewsbury River with the 

Atlantic Ocean. When fl'rst constructed in 1865 the railroad was often 

subject to damage due to storm indu'ced conditions. This resulted in the 

first extensive erosion control measures undertaken for the area. The 

railroad has since been abandoned and the tracks removed, however. the 

seawall remains. At present the peninsula varies in width from 250 to 

1500 feet at an elevation ranging from 5-10 feet above the National 

Geodetic Vertical Datum (NGVD). 

014. In the southern half of the study area. the existing bluffs once 

extended considerably seaward and have since been eroded back to their 

present position as a result of the combined effects of wind and waves. 

The bluffs immediately adjoining the ocean range in elevation from 10 to 

25 NGVD. with the higher elevations located to the northern portion of 

the area. 

015. The severely eroded condition of project area beaches has limited 

their attractiveness, as a recreation and c1evelopment resource. Even 

though the average berm width is only 24 feet. over 85,000 individuals 

utilized the public beaches in 1985. 

016. Human Resources. Population in Monmouth County increased by 

168,000 persons between 1960' and 1980. While this presents a 50% 

increase in 20 years, the recent trend towards smaller households has 

reduced the growth rate from 38% between 1960 and 1970 to 9% between 

1970 and 1980. Population estimates for 1985 indicate a 5.5% increase 

since 1980, the £ifth largest percentage increase in the state. The net 

population increase of 27,700 persons is the third largest in the state. 

ranking behind the bordering counties of Ocean and Middlesex. In 

general the greatest population growth has occurred in more rural 

western portions of the county with several exceptions including the 

communities of Sea Bright and Monmouth Beach. Projections of future 

population by the New Jersey Department of Labor, presented in Table 

0-1, indicate that Monmouth Co~nty will continue to grow somewhat faster 

than the state average and that growth in the borciering counties of 

Middlesex and Ocean W'ill cO,ntinue to exceed the Monmouth County rate. 

017. Population trends in the project area communities have varied 

widely with increasing population in the northern communities and 

decreasing population to the south. The total 1980 population for the 

six communities was 38,182 persons. a decrease of 2% from the 1970 

census. Since the City of Long Branch extends farther inland than the 

other communities this figure does not truly represent population trends 

along the coastline. Excluding Long Branch the remaining five 

communities had a net popu~ation increase of 16%. 

173 
D18. The project area communities are generally more wealthy than the 

county average. With the exception of Long Branch the communities had a 

per capita income of between 124% and 196% of the county average. In 

four of the six communities growth in per capita income between 1969 and 

1979 exceeded the county growth rate of 21%, but due to the large 

population and low growth rate in Long Br.anch the average increase in 

per capita income for all six communities is only 14.4%. 

D19. Table D-2 provides a summary of population and per capita income 

data for Monmouth County and .the individual communities in the project 

area. 

D20. Development and Economy. The majority of land in the immediate 

project area contains residential development with commercial development concentrated in the centers of Sea Bright and Long Branch. Recent 

development in the proj ect area mirrors the regional trend towards 

townhouse and condominium units, particularly in Sea Bright, Monmouth 

Beach and Long Branch. The coastal area has also seen a trend towards 

more year round housing. both in percentage of units and in numbers. 

Residential development trends of communities in the study area are 

presented in Table D-3. Between 1970 and 1980 the number of seasonal 

housing units declined 21% while the total number of housing units 

increased by over 15i.. 

D2l. Sea Bright, the northernmost community within the project area, is 

predominately residential except for the central business district 

adjacent to the public beach and scattered hotels, beach clubs and 

restaurants along Ocean Avenue. 

D22. Monmouth Beach, just south of Sea Bright, is also predominately 

residential with occasional beach .clubs and restaurants along Ocean 

Avenue and several marinas along the Shrewsbury River. The residential 

development in Monmouth Beach includes a significant number of high rise 

apartment buildings and townhouse .. complexes. 

D23. The City of Long Branch includes several communities with distinct 

development patterns. The northern portion of the city, known as North 

Long Branch, is mostly residential with an increasing concentration of 

townhouses and condominiums. The ocean front in this area is dominated 

by 7 Presidents Park, a county-run public beach. Non-residential 

development in this area includes several restaurants and a National 

Guard Armory. 

174 
...... 

..... 

VI 

TABLE 0-1 

PROJECTIONS OF FUTURE POPULATION 

HONMOUTH AND SURROUNDING COUNTIES 

Provisional 

Census Census Estimate* Projections t

Apdl I, April I, July I, --------------------------------------------

ill.L 1980 1985 1990 1995 2000 2005 

NEil JERSEY 1,111,112 1,365,011 7,S62,OOO 1,842,300 8,154,000 8,4S0,300 8.685,20

"ldd1esea County S8l,813 S9S,893 626,100 6Sl,600 690,600 126,600 160,80

HomRouth County 461,849 S03,I13 530,900 547,200 568,100 591,600 611,30

Ocean County 208,470 346,038 380,000 413,300 449,600 484,400 SI5,80

*The 1985 provlaJonal state .atlmate la rounded to the neareat thousand persons. The 1985 county estimat

the nearest hundred persons. 

SOURCE: New 'eraey Department of Labor, DlvJaJon of Plannin, and Research, Office of Deao,raphJc and Eco
TABLE 0-2 

SUMMARY OF POPULATION AND PER CAPITA INCOME TRENDS 

Per Capita Income 

Total Population (1979 Dollars) 

Town 1970 1980 % Change 1969 1979 % Change - Sea Bright 1,339 1,812 +35.3 7,772 11 ,840 +52.3 

Monmouth Beach 2,042 3,318 +62.5 8,976 13,471 +50.1 

Long Branch 31,774 29,819 -6.2 6,727 6,970 +3.6 

Deal 2,401 1,952 -18.7 13,047 16,694 +28.0 

Allenhurst 1,012 912 -9.9 7,943 10,649 +34.1 

Loch Arbour 395 369 -6.6 9,431 10,568 +12.1 

- Total/Average 

Project Area 38,963 38,182 -2.0 7,329 8,386 +14.4 

Monmouth Coun'ty 461,849 503,173 +8.9 7,054 8,539 +21.0 

No. of Households Persons Per Household 

Town 1970 1980 % Chanse 1970 1980 % Chanse 

Sea Bright / 555 941 +69.5 2.41 1.92 -20.3 

Monmouth Beach 685 1,336 +65.8 2.98 2.47 -17.1 

Long Branch 10,824 11 ,672 +7.8 2.86 2.51 -12.2 

Deal 754 650 -13.8 3.18 3.00 -5.7 

Allenhurst 309 328 +6.1 3.28 2.78 -15.2 

Loch Arbour 119 125 +5.0 3.32 2.95 -11.1 

Total/Average 

Project Area 13,246 15,052 +13.6 2.88 2.50 -13.2 

Monmouth County 135,230 170,130 +25.8 3.32 2.90 -12.7 

176 
Community 

Sea Bright 

Monmouth Beach 

Long Branch 

...... 

....... 

Deal 

....... 

Allenhurst 

Loch Arbour 

Total in 

Study Area 

Total County 

TABLE D-3 

STUDY AREA HOUSING TRENDS 

1910 Housing Units 

Year Year 

Round Seasonal Total Round 

614 124 798 1.009 

135 114 849 1,551 

11.561 402 11.963 12.906 

767 185 952 767 

.383 19 402 360 

131 29 160 141 

14,251 813 15,124 16,140 

143,021 7,448 150,469 180.428 

Source: Monmouth County Census Trends 

1970-1980 

1980 Housing 

% 

Change Seaso

+49.7% 121 

+111.8% 52 

+11.6% 265 

0% 166 

-6.0% 53 

+7.6% 26 

+17 .5% 689 

+26.2% 5.342 
D24. ~e center of Long Branch. once a leading resort for the wealthy. 

endured a long period of economic stagnation as improvements in regional 

transportation provided access to more southerly resorts. The current 

redevelopment of Long Branch is concentrated ana major hotel and 

convention center located adjacent to existing recreation facilities and 

the now vacant pier.·. The Long Braneh pier, ravaged by fire in the 

spring of 1987. is likely to be redeveloped as a recreation or shopping 

area and should provide further stimulus to the revitalization of the 

adjoining commercial areas. Business activity is concentrated along the 

boardwalk and includes numerous arcades, restaurants and food stands. 

D25. South of the Long Branch business district is the area known as 

Vest End. This area is characterized by townhouse and condominium 

development and a healthy retail district ~ear the Vest End public 

beach. 

D26. The area between Lake Takanassee and the Deal border is known as 

the Elberon section of Long Branch. This area of the coast is primarily 

developed with large single family residences interspersed with beach 

clubs. 

D27. south of the City of Long Branch lies Deal Borough. a partiqularly 

stable and wealthy residential· community. Notable non-residential 

development includes the Phillips Avenue Pavilion and the Deal Casino. 

D28. The Borough of Allenhurst and Village of Loch Arbour. are small 

communities at the southern limit of the project and are characterized 

by moderately expensive single family residences. 

D29. The economy of Konmouth County has undergone strong growth. in 

recent years with much of the development concentrated along major 

transportation routes. The majority of recent non-residential 

development has been for office and research facilities, probably due to 

the availability of comparatively inexpensive land with good access to 

the Northern New Jersey-New York City markets. 

D30. value of Improvements. Based on a structure inventory and damage 

survey, buildings and ancillary .structures within the immediate project 

area are valued at over 500 million dollars and contain over 125 million 

dollars in contents. Table D-3A provides a SWlUll&ry of structure values. 

aoads and utilities adjacent to the,horeline are valued at over 14 

million dollars. The 1986 Konmouth County tax aueument of value for 

towns in the project area is 1 billion. 280 million dollars. 

DESCRIPTION OF THE PROBLEK 

D31. The Erosion Problem. .Er08ion has seriously reduced the width of 

most beaches in the study area with consequent exposure of the ,hare to 

storm damage. Throughout the period of record the 1Z-mile study area 

has experienced continuous beach erosion resulting in a majority of the 

shore front property in Sea Bright and Konmouth Beach having no dry 

beach. With the exception of sand fillets south of groins, very little 

beach width remains in the southern section of the study area. 

178 

CRev. Karch 1990) 
t-o 

...... 

\0 

'"' lld 

ID 

< 

. 

;:: 

'1 

n 

:r 

..-

\D 

\D 

o 

-

REACH 

TABLE D-3A 

SEABRIGHT TO OCEAN TOWNSHIP 

STRUCTURE VALUE TABULATION BY REACH 

JUNE 1988 PRICE LEVEL 

DOLLARS (IN TOUSANDS) 

RESIDENTIAL STRUCTURES NON-RESIDENTIAL STRUCTU

VALUE * , VALUE 

====== -========================== ========================

1 $23,318 228 $10,205 1

2 $22,155 176 $27,284 1

3 $27,606 91 $17,613 

4 $47,418 96 $3,421 

5 $55,301 128 $6,586 

6A $8,368 12 $9,939 6B $12,298 141 $18,460 

7 $55,360 13 $9,838 

8A $70,381 52 $22,615 

8B $16,127 86 $18,813 

9A $20,108 69 $6,763 

9B $5,267 19 $63 

10 $12,796 44 $1,242 11 $15,194 69 $1,005 

---------------

-------------- 

TOTALS $392,303 1350 $153,907 7

• Residential Values include: single and multifamily res

apartment buildings, townhouse buildings and highrise 
D32. Virtually all of the protective coastal structures, including the 

massive seawalls and 103 groins, have deteriorated since their construction. The structures are becoming increasingly susceptible to storm 

wave damage as the beach continues to erode. The recreational beach 

areas continue to shrink as the State recreational need increases. 

D33. The existence of sand fillets at the south sides of groins and the 

elongation of the northern end of Sandy Hook indicate a net northward 

movement of littoral drift in the study area. Recent erosion information 

indicates an increasing rate of loss of beach material northward along 

the study area. The actual annual net littoral drift rate was estimated 

to be approximately 155,000 cubic yards toward the north at Ocean 

Township and 493,000 cubic yards at Sea Bright. Since the beach itself 

is the only source of material, it is inevitable that the beach has and 

will continue to erode. 

D34. The Storm Problem. The project area has a recorded history of 

damage and economic loss due to coastal storms dating back to 1889. 

Significant storms were recorded in 1896, 1913, 1914, 1938, 1944, 1950, 

1953, 1960, 1962, 1972, 1976, 1984 and 1985. Storms such as these cause 

widespread damage throughout the study area from a combination of wave 

attack, storm recession and inundation. In addition, localized flooding 

due to unusually high tides cause limited damage and road closings up to 

8 or 10 times a year. 

D35. Documented damage reports, available for the March 1962 and March 

1984 Storms. demonstrate the destructive potential of storms in the 

project area. Both of those extratropical storms caused major damage 

and resulted in disaster area declarations. Updating to June 1988, 

damages are estimated at 26.5 million dollars for the 1962 storm and 

16.7 million dollars for the 1984 storm. Dollar figures are updated 

from post storm reports which reflect damages occurring at that time. 

Updating does not take into account the impacts of increased development. regional trends in real estate value. or continued erosion and 

undermining of the protective structures. 

D36. Due to continuing shoreline erosion with attendant degradation of 

protective structures and increased coastal development. the potential 

economic losses and threat to human life and safety continue to rise 

with each passing year. 

EXTENT AND SCOPE OF ALTERNATIVES 

D37. The authorized project provides for Federal participation in the 

restoration and protection of the shore from Sea Bright to Ocean 

Township by artificial placement of sand to widen the beach to a minimum 

width of 100 feet at an elevation of 10 feet above mean low water and by 

the construction of 23 new groins and the extension of 14 existing 

groins in the Sea Bright .to Ocean .Township section. Based on preliminary 

screening as shown in Table D3A, a total of three berm widths were 

e.aluated: 50 feet, 100 feet and 150 feet for a beach fill only plan, as 

well as for an updated groin plan and the authorized groin plan. After 

identifying the plan and berm width providing maximum net benefits the ~pacts of berm caps of 0 feet, 2 feet and 4 feet above the authorized 

berm were evaluated to ensure the maximum storm protection benefits. 

180 
1-

:;Q 

<: 

t1 

g. 

..... 

\0 \0 

o 

'-" 

..... 

00 

..... 

INITIAL SCREENING OF 

STORM DAHAGE ALTERNATIVES 

SEA BRIGHT TO OCEAN TOWNSHIP, N.J. 

TECHNICAL SOCIAL ANNUAL COST FURTHER 

ALTERNATE FEASIBILITY IHPACT ($1.000) CONSIDERATA. No Actior 

B. Buy-Out Plan 

C. Beach Restoration 

D. Authorized Groins 

E. Groins ·with Beach 

Restoration 

F. Seavalls 

Yes 

Yes 

Yes 

Yes 

Yes 

Yes 

G. Seavalls with Beach Yes 

Restoration 

H. Revetments Yes 

Eventual loss 

of beach 

Socially 

Unacceptable 

Provide usable 

beach area and 

storm protection 

Reduced aesthetics. 

Increased impact 

at Sandy Hook. 

Reduced 

aesthetics. 

Usable beach. 

Eventual 1088 

of dry beach 

Usable beach. 

Excellent stom 

protection. 

Eventual loss 

of beach. 

$0 

$78,320 

$17,678 

$791 

$18,272 

$4,435 

$21,811 

$2,902 

No 

No 

Yes 

No 

Yes 

No 

No 

No 
I-' 

00 

N 

-

i 

. 

;:: 

t1 

n 

:T 

.... 

o 

...... 

TABLE D-3B (continued) 

INITIAL SCREENING'OP 

STORM DAMAGE ALTERNATIVES 

SEA BRIGHT TO OCEAN TOVNSHIP. N.J. 

TECHNICAL SOCIAL ANNUAL.COST F

ALTERNATE PLAB___ PEASIBILITY IHUCT($l.OOO) C

I. Revet.ent. with Yel 

Beach Reltoration 

J. BreaK.aterl Harginal 

K. Break.atera with Harginal 

Beach Reltoration 

L. Perch with Beach 

Reltoration 

No 

Provide ulable 

beach area. 

could pOle 

hazard to 

boaterl. 

Could pOle 

hazard to 

boaterl. 

Could pose 

hazard to 

boaterl. 

$20.9tf2 

$7.051 

$23.104 

$19.128 
STORM DAMAGE 

GENERAL 

D38. Conditions. The base year for this economic evaluation is 1990. 

Since the project life is determined to be 50 years, damages were 

evaluated for the period 1990-2Q40 using the fiscal year 1988 

interest rate of 8-5/8%. For the year 1985, the year for. conditions 

of the study, a breakdown of damage causes is given in Table D-4. 

Due to the impact of long-term erosion, total damages vary in ,future 

years. 

D39. Methodology and assumptions. Benefits from the proposed plans 

of improvement were estimated by comparing damages with and without 

the proposed project under existing development conditions.· In 

calculating storm reduction benefits, the type of damage causing the 

maximum impact was identified at each structure for various storm 

frequencies. To prevent double counting only this maximum damage was 

included in the calculation of project benefits. Structures 

destroyed by long-term erosion were removed from the analysis for 

future years as it was determined they would not be reconstructed 

because the site was destroyed. For buildings destroyed by storm 

recession and/or wave attack, existing development patterns indicate 

that they would be rebuilt unless subject to wave or storm recession 

damage from storms with a recurrence interval of 1.5 years or less. 

In areas protected by the seawall, total rebuilding was considered 

based on perception of protection provided by the seawall. This was 

based on a review of existing development which presently reflects 

this proximity to the shore line. 

Effective 

Flood Stage* 

(NGVD) 

8 

10 

12 

14 

TABLE D-4 

BREAKDOWN OF WITHOUT PROJECT DAMAGES 

EXISTING CONDITIONS 

% of Total Damage 

Storm Recession Wave Attack Inundation 

14 

14 

9 

8 

24 

30 

51 

55 

62 

56 

40 

37 

*Includes Wave Setup Where Applicable 

For residential structures the replaced building was consider.ed to be 

elevated to meet the National Flood Insurance 'criteria, however, due to 

the impracticality of elevating the majority of low~lyin'g' commercial 

establishments (the center of Sea Bright) 'non-reside.ntial structures 

were considered to be replaced in kind. A review of the Flood Insurance 

maps for the area showed the 100-year design criteria to approximate the 

25-year ocean stage determined by this investigation. Thus a 25-year 

level of protection was the criteria set for evaluating future losses. 

183 
Conversations with PIKA representatives indicated that this assumption 

is further substantiated because the structures' do not lie vithin the 

high hazard 'V' zone as defined by PEHA and therefore are not required 

to be designed to sustain wave impacts. In addition, FIA criteria does 

not take into account storm recession vhich would further weaken 

foundation designs tending to lower the actual level of protection more 

in accord with the 2S-year .vent,' Pigure D-4 provides a seneralized 

flov chart of the analysis methodology. . 

D40. Inyentory. To accomplish the benefit analysis the initial consideration vas the development of a ,tructural data base to a .. ist in 

predictins storm damases. 

D41. Survey methodology. The structural data base was generated 

through a survey of the structures adjacent to the project area and 

includes buildinss, utilities, bulkheads, seawalls and roadways. The 

building data vas obtained through a vindshield survey of the area using 

topographic mapping with a scale of 1· • 200· with a 2-foot contour 

interval. Table D-5 indicates the type of physical characteristics 

obtained for the building inventory. For utilities, bulkheads, seawalls, etc., the inventory data vas taken from the topographic mapping 

and is primarily targeted tovard physical characteristics such as size 

and length in order to assign a replacement value. A key element in 

both aspects of the structure inventory is the front of structure 

setback and mid point setback data, used to locate each structural 

element relative to the vater line. This was the primary mechanism used 

to trigger damage due to long-term erosion, storm recession and vave 

runup. 

D42. The data collected vas used to categorize the structure population 

into groups having common physical features. Data pertaining to structure usage, size and stories assisted in the stratification of the 

building population. For each building, data was also gathered pertaining to its daaale potential including its main floor elevation lovest 

opening, construction material and proximity to the water. leplacement 

value was calculated for the residential and commercial structures using 

standard estimating guides in conjunction vith size data. 

D43. For non-building structures, such as roads, boardwalks, utility 

lines, ••• walls, etc., a similar inventory vas conducted by extracting 

data froa the mapping. Once collected, the information was encoded for 

use on a computerized data base giving an oyerall picture of the flood 

plaiD population. 

D44. pamace Survey. Folloving the completion of the inventory, a 

suple population of buildings vas selected for on-site inspection to 

deteraine damage potential. Findings from the on-site intervievs 

conducted for the sample population were then used to formulate 

leneralized depth-damage relationships to be applied to the overall 

population. A total of two hundred site investigatious vere to be 

conducted. The inventory population yas stratified according to 

physical characteristics, structure usage and susceptibility to flooding 

for the selectien of a representative sample. Care vas taken to assure tha~ •• ch group in the stratified population vas represented in the 

184 
TABLE D-5 

PHYSICAL CHARACTERISTICS OBTAINED 

FOR BUILDING INVENTORY 

1) Type - Residential. Cogmercial, etc. 

2) Town 

3) Zone 

4) Location ID 

5) Map Number 

6) Structure ID 

7) Set Back Distance 

8) Mid Point Distance 

9) Structure Size 

10) Stories 

11) Usage 

12) Basement/Foundation 

13) Ground Elevation 

14) Main Floor Height 

15) LowOpening 

16) Number of Garage Openings 

17) Exterior Material 

18) Units on First Floor 

19) Total Units 

20) Number of Buildings 

21) Q~ality 

22) Owner Operator 

185 
sample population. On site inspections vere conducted at the sample 

locations to determine damage potential for various flood depths and to 

determine historic damage vhere available. The historic damage data vas 

used to calibrate the potential damage at each.tructure by providing a 

known reference point in the depth damage .val~tion. The final 

population .ample distribution is .hown in Table D-6. 

D45. leach Selection. To assist in determinina those areas most 

su.ceptible to floodina and thus the primary areas for sample selection, 

economic reacl1 •• vere defined. . '!'he. init,ial breakdown .. as by municipal 

boundary folloved by physical characteristics. The primary physical 

split vas bet .. een the peninsula section in the north and the mainland to 

the .outh. Within each section a' further breakdown into reaches is 

indicated by coastal dynamics and man-made structures such as groin., 

.eavall., etc. This procedure yielded the reaches shown in Figures D-S 

and D-6. 

D46. Sample selection. A reviev of the topography of the area revealed 

the northern sector to be potentially the most .usceptible to flooding 

and vave attack damage and to a lesser extent, lov-lyina areas near 

Takanassee Lake and Deal Lake. This included reaches 1 through 5 and 

the lake areas of reaches SA, 8B and 11. For the remaining reaches the 

potential for storm damage is primarily limited to underminina from 

erosion or storm recession and failure from vave runup. For this reason 

the northern peninsula portion of the project area and properties 

adjacent to the lakes vere the primary centers for on-site investigation. Intervievs vere taken outside these locals only vhen .tratified 

u.age types either did not exist or vere unobtainable vithin these 

primary areas. For example. the Long Branch pier vas unique to the 

.tudy area and as such flood damage intervievs pertaining to arcades 

could only be'obtained at this location. 

D47. Description of damage functions • Generalized damage functions 

ver •• enerated fez physical damage, emergency COltl, lOlt income and 

residential content damage. ~hese damage functions reflect damages per 

square foot of structure size vhich vere than applied to each structure 

to determine damages at 1 foot 'increments of flood Itage. For nonre.idential .tructures the damage surveys evaluated the depth-damage 

relationship for physical, lost income, and emergency co.ts ba.ed OD an 

a ••••• ment of the .ites vi.ited. For the residential .tructures, FtA 

curve. vere utllizedto develop the physical damages based on total 

value of the Contents and Structure. Lost Income and Emergency losses 

vere based on intervie" data. 

D47A. The analysis of lost income benefitl vas based solely on 

residential damage surveys, and therefore eliminatel double counting 

businesl and household lost income vhile allo avoiding transfers of 

economic activity vhich are prevalent vhenthe lOIS of ineome to local 

business firms i. measured. Double counting of income lo.s and 

emergency co.ts vas avoided by considering the evaluation of emergency 

costs, .uch as flood fight, evacuation and clean-up. net of any income 

lo.ses identified during the damage lurvey.. Also, an upper limit of 40 

hours of income loss per household vas assumed so as to eliminate .urvey 

re.pon.es vhich did not accurately distinguish betveen income lost due 

to damage to place of employment or time .pent for clean up and repair. 

186 (lev. Xarch 1990) 
TABLE D-6 

SEABRIGHT TO' OCEAN TOWNSHIP 

INTERVIEW SAMPLE DISTRIBUTION 

Usage 

POEulaUon TarBet Samele Actual Samele 

% of %of % of 

I % , TarBet , S!!ple Poeulation 

1. Colonial 477 22.4 31 15.5 37 17.3 7.8 

2. Cape Cod 149 7.0 12 6.0 16 7.5 10.7 

3. Ranch 175 8.2 10 5.0 11 5.1 6;3 

4. Split lAvel 17 0.8 1 0.5 2 0.9 11.8 

5. BiLevel 4 0.2 1 0.5 1 0.5 25.0 

6. Raised Ranch 36 1.7 3 1.5 3 1.4 8.3 

7. BungalQw 140 6.6 12 6.0 13 6.1 9.3 

8. Custom 65 3.0 5 2.5 6 2 •. 8 9.2 

9. Mobile Home 0 0 0 0 0 0 

10. 2-Family 61 2.9 4 2.0 5 2.3 8.2 

11. Duplex 30 1.4 2 LO 2 0.9 6.7 

12. Multi-Family 41 1.9 2 1.0 2 0.9 4.9 

L3. Garden Apt. 67 3.1 4 ' 2.0 5 2.3 7.5 

l4. Bigh-Rise 12 0.6 2 1.0 2 0.9 16.7 

L5. Townhouse 76 3.6 6 3.0 8 3.7 10.5 

187 
TAB~E D-6 (continued) 

SEA BRIGHT TO OCEAN TOWNSHIP 

INTERVIEW SAMPLE DISTRIBUTION 

Usage 

POEulation Taraet SamEle Actual SamEle 

% of % of % of 

11 % II Taraet II SamEle POEulation 

20. Arcade 9 0.4 2 1.0 2 0.9 22.2 

21. Art Gallery 0 0.0 0 0 0 0 

22. Auto Sales 2 0.1 1 0.5 1 0.5 50.0 

23. Auto Service 4 0.2 1 0.5 2 0.9 50.0 

24. Bank 3 0.1 1 0.5 1 0.5 33.3 

25. Bar 10 0.5 2 1.0 1 0.5 10.0' 

26. Bath House 13 0.6 3 1.5 3 1.4 23.1 

27. Church 3 0.1 1 0.5 1 0.5 33.3 

28. Clothing Store 5 0.2 2 1.0 2 0.9 40.0 

29. Department Store a 0.0 0 a a 0 

30. Diner 29 1.4 6 3.0 6 2.8 20.7 

31. Drug Store 2 0.1 1 0.5 1 0.5 50.0 

32. Dry Cleaning 4 0.2 2 1.0 2 0.9 50.0 

33. Food Store 10 0.5 2 1.0 2 0.9 20.0 

34. Funeral Home a 0.0 0 0 0 0 

35. Hair Salon 3 0.1 1 0.5 1 0.5 33.3 

36. Hardware 6 0.3 2 1.0 2 0.9 33.3 

37. Home Furnishings 2 0.1 1 0.5 1 0.5 50.0 

38. Hospital 0 0.0 0 0 0 0 

39. Indoor Sports 4 0.2 1 0.5 1 0.5 25.0 

40. Jewellers 0 0.0 0 a a a 

41. Liquors 2 0.1 1 0.5 L 0.5 50.0 

42. Marina 10 0.5 5 2.5 5 2.3 50.0 

43. Medical Offiee a 0.0 a 0 a a 

188 
TABLE D-6 (continued) 

SEA BRIGHT TO OCEAN TOWNSHIP 

INTERVIEW SAMPLE DISTRIBUTION 

Usage 

Po;eulation Taraet Samele Actual Samele 

% of % of 7. of 

/I % II Taraet /I SaIllJ?le Poeulation 

44. Office 14 0.7 4 2.0 5 2.3 35.7 

45. Office Warehouse 1 0.1 1 0.5 1 0.5 100.0 

46. Outdoor Sports 2 0.1 1 0.5 1 0.5 50.0 

47. Restaurant 21 1.0 7 3.5 7 3.3 33.3 

48. Rooming House 33 1.5 6 3.0 7 3.3 21.2 

49. Small Retail 12 0.5 5 2.5 5 2.3 4'1.7 

50. Theaters 0 0 0 0 0 0 

1r51. Vacant 16 0.7 0 0 a a 

52. Cabana 83 3.9 8 4.0 8 3.7 9.6 

53. Beach Club 23 1.1 7 3.5 7 3.3 30.4 

54. Amusement Rides 5 0.2 1 0.5 1 0.5 20.0 

71. Food and 

Kindred Product 1 0.1 1 0.5 1 0.5 100.0 

72. Extraction a 0.0 a a a 0 

73. Textiles and 

, Apparel a 0.0 a a a a 

74. Lumber and Wood 2 0.1 1 0.5 1 0.5 50.0 

75. Furniture and 

Fixtures 1 0.1 1 0.5 1 0.5 100.0 

76. Paper Products 0 0.0 a a 0 0 

77. Printing and 

Publishing. 1 0.1 1 0.5 1 0.5 100.0 

78. Chemicals 0 0.0 0 0 0 a 

79. Fuel Storage a 0.0 a a a a 

80. Glass, Clay 

and Concrete a 0 .. 0 a a a a 

81- Metal Working 0 0.0 0 0 0 0 

82. Electrical a 0.0 a a a 0 

83. Transportation 

Equipment a 0.0 a a a a 

84. Warehouse 7 0.3 3 1.5 3 1.4 42.9 

85. Building 

Contractor 1 0.1 1 0.5 1 0.5 100.0 

189 
Usage 

TABLE 0-6 (continued) 

SEA BRIGHT TO OCEAN TOWNSHIP 

INTERVIEW SAMPLE DISTRIBUTION 

P02ulation Tarset Sam21e Actual 

% of 

{I % II Tarset II 

101. Sewage Treatment 0 0.0 0 0 

102. Pump Station 4 0.2 2 1.0 2 

103. Gas Substation 0 0.0 0 0 0 

104. Water Treatment 0 0.0 0 0 0 

105. Wells 0 0.0 0 0 0 

106. Electric 

Substation 1 0.1 1 0.5 1 

107. Miscellaneous 2 0.1 1 0.5 1 

**150. Garage 293 13.7 0 0 0 

**151. Tennis Court 14 0.7 0 0 0 

**152. Swimming Pools 54 2.5 0 0 0 

**153. Bath House 

(Residential) 5 0.2 0 0 0 

**154. Gazebo 7 0.3 0 0 0 

**156. Boat Dock 

(Private) 30 1.4 0 0 0 

201. Fire House 3 0.1 1 0.5 1 

202. Storage Garage 8 0.4 3 1.5 3 

203. Municipal 

Building 2 0.1 1 0.5 1 

204. Municipal 

Complex 0 0.0 0 0 0 

205. Police Station 1 0.1 1 0.5 1 

206. Schools 0 0.0 0 0 0 

207. Rescue Squad 1 0.1 1 0.5 1 

208. ~ibrary 0 0.0 0 0 0 

209. Post Office 1 0.1 1 0.5 1 

*210. General Storage 14 0.7 5 2.5 4 

Total m 

*Vacant Structures. No Interviews Taken 

**Ancillary Structures. No Interviews Ta~en 

190 

Sam21e 

% of %of 

Sam21e POEulation 

0 0 

0.9 50.0 

0 

0 

0 

0.5 100.0 

0.5 50.0 

0 

0 

0 

0 

0 

0 

0.5 33.3 

1.4 37.5 

0.5 50.0 

0 0 

0.5 100.0 

0 

0.5 100.0 

0 

0.5 100.0 

1.9 28.6 
DAMAGE MECHANISMS 

D48. In a coastal environment, flood damages occur as a result of a 

number of different yet interrelated causes. Structures become undermined and falloff into the ocean due to long-term erosion which occurs 

over a number of years o.r during a single event as a result of storm 

recession. Structures be,come inundated as a result of storm surge 

resulting in damage due to saturation of materials and hydrostatic 

pressures. Under certain storm conditions wind blown waves often add to 

these forces and destroy the structure. Because of the interdependency 

of these damage mechanisms, it is important to avoid double counting, 

therefore only the mechanism yielding. the ma~imum damage for a given 

return frequency has been used for the project's benefit cost-analysis. 

The following outlines how each damage mechanism was evaluated independently. 

Long Term Erosion Damages 

D49. Years and limitations. Based on the long-term erosion rate of 3 

'feet per year, the area subject to long-term erosion was determined for 

the years 1990, 2000, 2010, 2020, 2030 and 2040. Based on discus.ions 

with the New Jersey Department of Environmental Protection, Division of 

Coastal Resources, it was determined that ongoing maintenance efforts 

would protect major structures such as the Seawall and State Highway. 

Long Term Erosion would therefore be arrested at the leading edge of 

these structures through intervention by man, thus no long-term erbsion 

was considered beyond the seawalls and roadways paralleling the beach. 

D50. Methodology. In determining damage due to long-term erosion 

undermined structures were considered a total loss and would not be 

rebuilt. The value of each structure impacted by long-term erOSion was 

removed from the evaluation when considering storm induced damages in 

subsequent years. 

D51. The costs associated with halting long term erosion at seawalls, 

and bulkheads are reflected in the without proj ect seawall maint,enance 

costs. The cost of protecting major roads exposed to long term erosion 

was calculated for years PO, PI0, P20, P30, P40 and P50 using the 

following formula: 

Annual Cost - Project Annual x 

Maintenance Cost 

Length of roadway impacted 

Length of Project 

The calculation of these costs is presented in Table D-7. 

D52. The major impact of long-term eroSion is the reduction in berm 

area protecting structures from the impact of storm damage due to 

shoreline recession, wave impact and wave runup. 

D53. The project as proposed will halt long-term erosion as a result of 

implementing the feeder beach and an ongoing maintenance program 

reflected in the project costs. Residual with project damages were 

therefore calculated without consideration for long-term erosion. 

191 
TABLE D-7 

SEA BRIGHT TO OCEAN TOWNSHIP 

Erosion Benefits Calculation Sheet 

Por Roadway Protection 

Reach 6A 

Interest Rate 8.625% 

Maintenance Cost $ 69 /ft/Yr 

Project Life 50 Years 

DATE PROJECT LENGTH OP VALU! IN PliP PRESENT 

YEAR YEAR ROADWAY (PT) YEAR WORTH 

1990 0 0 $0 1 $0 

1991 1 0 $0 0.920 $0 

1992 2 0 $0 0.847 $0 

1993 3 0 $0 0.780 $0 

1994 4 0 $0 0.718 $0 

1995 5 0 $0 0.661 $0 

1996 6 0 $0 0.608 $0 

1997 7 0 $0 0.560 $0 

1998 8 0 $0 0.515 $0 

1999 9 0 $0 0.474 $0 

2000 10 0 $0 0.437 $0 

2001 11 12 $828 0.402 $333 

2002· 12 24 $1.656 0.370 $614 

2003 13 36 $2.484 0.341 $847 

2004 14 48 $3.312 0.314 $1.040 

2005 15 60 $4.140 0.289 Sl.197 

2006 16 72 $4.968 0.266 Sl.322 

2007 17 84 $5.796 0.245 $1.420 

2008 18 96 $6.624 0.225 $1.494 

2009 19 108 $7.452 0.207 $1.547 

2010 20 120 $8.280 0.191 $1.583 

2011 21 143 $9.867 0.175 $1.736 

2012 22 166 $11.454 0.162 $1.856 

2013 23 189 $13.041 0.149 $1.945 

2014 24 212 $14.628 0.137 $2.008 

2015 25 235 $16.215 0.126 $2.050 

2016 26 258 $17.802 0.116 $2.072 

2017 27 281 $19.389 0.107 $2.077 

2018 28 304 $20.976 0.098 $2.069 

2019 29 327 $22.563 0.090 $2.048 

2020 30 350 $24.150 0.083 $2.018 

2021 31 365 $25.185 0.076 $1.938 

2022 32 380 $26.220 0.070 $1.857 

2023 33 395 $27.255 0.065 $1,777 

2024 34 410 $28.290 0.060 $1.698 

2025 35 425 $29.325 0.055 $1.621 

2026 36 440 $30.360 0.050 $1.545 

2027 37 455 $31.395 0.046 $1,470 

192 
TABLE D-7 

SEA BRIGHT TO OCEAN TOWNSHIP 

Erosion Benefits Calculation Sheet 

For Roadway Protection 

Reach 6A 

Interest Rate 8.625% 

Maintenance Cost $ 69 /ft/Yr 

Project Life 50 Years 

DATE PROJECT LENGTH OP VALUE IN PWP PRESENT 

YEAR YEAR ROADWAY (FT) YEAR WORTH 

2028 38 470 $32,430 0.043 $1,398 

2029 39 485 $33,465 0.039 $1,328 

2030 40 500 $34,500 0.036 $1,261 

2031 41 517 $35,673 0.033 $1,200 

2032 42 534 $36,846 0.030 $1,141 

2033 43 551 $38,019 0.028 $1,084 

2034 44 568 $39,192 0.026 $1,029 

2035 45 585 $40,365 0.024 $975 

2036 46 602 $41,538 0.022 $924 

2037 47 619 $42,711 0.020 $875 

2038 48 636 $43,884 0.018 $827 

2039 49 653 $45,057 0.017 $782 

2040 50 670 $46,230 0.015 $739 

Present Worth of $56,747 

Protection Costs 

XCRF 50 0.088 

Actual Cost of $4,974 

Road Protection 

193 
D54. The actual methods of analyses for other types of storm-induced 

damage are described in subsequent paragraphs. 

Storm Recession Damages 

D55. The project area is potentially subject to significant storm 

induced shoreline recession which becomes increasingly more damaging as 

long-term erosion reduces the ability of t.he beach to provide a protective buffer. Unlike long-term erosion which is assumed to halt at 

seawalls and major access roads, storm recession occurs over a short 

period during the course of a major storm, thereby preventing interruption by man and thus may impact any structures including those protected 

by the seawall. In areas protected by the seawall or bulkheads. the 

recession is temporarily halted until frequencies significant enough to 

cause wall failure are reached. Once this occurs. recession occurs 

beyond the structure. Table D-8 indicates the frequency at which the 

seawall and bulkheads. are anticipated to fail under existing conditions 

and with alternative berm widths at the authorized berm height. 

D56. The storm recession-frequency data used for the economic analysis 

were based on data developed by CERC and presented in the report:, 

entitled "Coastal Processes at Sea Bright to Ocean Township. N.J" Ct:RC, 

1987. As recommended in this report, the data incorporates adjustment 

factors for longshore variability in recession distances. In order to 

more accurately define the area impacted by recession, a variability 

factor of 2.0 was applied for existing conditions to the average berm 

recession distance as determined from modeling studies of idealized 

profiles. This longshore variability is caused by variations in storm 

forces and beach characteristics such as, onshore slope. offshore slope, 

berm height or width, grain size and vegetation. Since the With P'roject 

beaches will exhibit far more regularity, a variability factor of 1.5 

has been utilized for the With Project conditions. This adjusted 

distance represents the maximum recession expected on 75% of the shoreline, 25% of the shoreline receding a greater distance. By comparison 

the median which is reflected prior to the application of the variability factor represents recession expected to occur on 50% of the 

shoreline. with 50% actually receding a greater distance. Further 

discussions on the variability factor are contained in Appendix A. 

D57. Since the probabHity of recession, including the variability 

factor occurring in any location, is one half the probability of the 

median recession occurring at that location, recession damages have been 

reduced by 50%. Thus with the variability factor included, the damages 

occur at a lower frequency than without the consideration of variability 

but the dollar value of the damage is one half. 

194 
TABLE D-8 

STORM RECURRENCE INTERVAL 

FOR SEAWALL OR BULKHEAD FAILURE 

Storm Recurrence Interval (Years) 

Existing 10' MlW 10' MLW 10' M!.W 

Reach Condition 50' Berm 100' Berm 150' Berm 

1 10 50 200 1000 

2 SO SO 200 1000 

3 50 50 200 1000 

4 80 80 200 1000 

5 50 50 200 1000 

6B 10 50 200 1000 

7 200 200 200 1000 

8B 10 50 200 1000 

9B 200 200 200 1000 

10 5 50 200 1000 

NOTE: TOTAL SEAWALL FAILURE IS ASSUMED AFTER 45% DAMAGE 

195 
D58. Methodology for evaluating storm recession damages. The potential 

damage to any structure was determined based on the structure replacement value, content value, lost income and emergency costs as determined 

from sample interviews. Damage was assumed to begin when the recession 

distances exceeded the leading edge of the structure as defined by the 

set back distance with total damage occurring when recession reached the 

midpoint of the structure. Damage between these two points was determined using linear interpolation. 

D59. Recession damage was analyzed for existing conditions and for each 

decade .. of the project life. Analysis of future damage was based on 

shoreline positions adjusted for long term erosion. Based on historical 

trends those structures destroyed by storm induced recession were 

assumed to be rebuilt. This reflects the ability of the shoreline to 

quickly recover the majority of its loss. That portion of the shore 

that is not fully recovered is taken into account in the long term 

erosion rate. Accordingly, any structures lost to long term erosion 

were removed from the analysis in subsequent years due to the permanent 

loss of land. 

D60. Residual recession damage for each plan was evaluated using the 

same methodology excluding long term erosion since project maintenance 

will prevent its occurrence. Set back and midpoint distances were 

adjusted for the additional beach width and the seawall failure 

frequency was adjusted to reflect the increased level of stability 

provided by each project. 

Inundation Damages 

D61. General. The project area is currently subject to inundation from 

several sources including waves overtopping the seawall and flooding in 

the Navesink and Shrewsbury Rivers; Presently, throttling of the storm 

surges through the Raritan Bay and up the Shrewsbury River cause a 

reduction of 2 to 4 feet in flood levels caused by the ocean. .Failure 

of the seawall would reduce or eliminate the throttling effect and cause 

substantially increased flood levels along the River. The proposed 

project beaches, though in themselves not greatly reducing flood depths, 

will substantially improve the integrity of the seawall thus mitigating 

the direct impact of ocean stages on the back side of the peninsula. 

D62. Utilizing the data from on-site investigation of the sample 

population, generalized damage functions were generated. The damage 

functions reflect the anticipated damage as a percent of building size 

for one foot increments of depth related to the structure's main floor. 

The damage functions were divided into Physical. Residential Contents, 

Lost Income and Emergency Costs. Employing the basic assumption that 

within usage stratification there is a direct correlation between 

structure size and damage, the potential damage for the overall 

population was es.timated by multiplying the siz'e of each s.tructure by 

its app~opriate damage function. This produces dollar damage per foot 

of inundation relative to each structure's main floor. When integrated 

with Stage Frequency data it permits the calculation of damages due to 

inundation associated with a specific return period. 

196 
D63. The stage-frequency curve used for determination of ocean related 

flood depths included the influence of wave setup. Higher water elevations associated wit1:\ wave runup were not evaluated for inundation 

damage since these elevations are intermittent and short term by nature 

and the flood depths within a building rarely reflect the exterior 

elevations. Damages from wave runup were evaluated solely from a 

hydrodynamic basis and are described under wave attack damage. 

D64. Wave Overtopping. In the northern section of the project area, 

structures are protected from direct ocean flooding by a massive seawall. The lack of beach in front of the seawall not only threatens its 

structural integrity, but because significant waves are able to directly 

impact on the wall, runup results in overtopping and subsequent flooding 

landward of the seawall. 

D65. Since overtopping rates and depths of flooding vary widely even 

fC?r storms with similar recurrence intervals due to various storm parameters, the analysis developed depth-frequency curves directly from 

known flood marks. The upper limit of the overtopping analysis was the 

frequency at which the seawall loses its structural integrity as 

detailed in Table D-8. At this point it was assumed that there is 

direct flooding from the ocean. 

D66. The basic approach to determining damage due to overtopping was to 

develop a depth-frequency curve for each reach based on flood marks. 

Because there is a slight gradient from the ocean toward the Shrewsbury 

River, it was necessary to adjust the flood stage as the water moved 

landward. This scenario is schematically displayed in Figure D-7. To 

achieve this a constant depth-frequency was assumed based on historical 

flood mark data and the stage adjusted based on the gradient of the 

ground. The area was divided- into grids with the approximate dimensions 

of 1000 feet parallel to the shoreline and 100 feet perpendicular to the 

shoreline. Within each grid, flooding at the lowest ground point was 

assumed to occur at depths determined from the depth-frequency curves. 

Damage due to overtopping was then calculated for each structure. A 

depth of one foot of water at the lowest point in each cell was the 

minimum frequency evaluated. 

D67. Depth-frequency curves were developed from historic flood marks 

and flood marks collected during damage interviews in conjunction with 

frequency data for the Sandy Hook gauge provided by NOAA Tidal Records 

section. This methodology was proofed against photographs taken during 

the syzygy tides of January 1987 and found to be in concurrence. 

197 
068. Wave Attack Oamage. Oceanfront structures are subject to forces 

in excess of inundation as a result of direct wave impact and high 

energy runup. To evaluate this added potential for structural failure. 

it is first necessary to define the population subject to wave forces. 

Two separate and distinct mechanisms were utilized to define the limits 

of potential wave attack. The initial technique consists of transmitting 

a potential incoming wave landward until such point that a breaking wave 

of 2.3 feet could no longer be sustained. The methodology utilized for 

the analysiS follows procedures outlined in the FEMA Manual "Ways of' 

Estimating Wave Height in Coastal High Hazard Areas". The process takes 

into account energy losses associated with natural and man-made barriers 

as the wave is transmitted landward. The height of 2.3 feet was selected based on structural evaluations conducted along the South Shore of 

Long Island for a previous study in which this breaking wave height was 

determined to sustain enough force to cause structural failure. The 

wave zones were so delineated for storms with return periods of 25, 100 

and 500 years. All delineations assumed complete failure of seawalls 

and bulkheads but damage to buildings was not considered for storms 

which would not cause failure of the protective structures. 

069. Subsequent analysis conducted for this investigation indicated a 

wave height slightly more than three feet was necessary to cause failure 

as described further on in this section. This means the wave zones 

delineated are slightly larger than necessary. The wave height 

necessary for failure is calculated based on the average size and 

orientation to the shoreline of the structures in the wave zone 

population and thus the difference in results. The 2.3 foot wave' was 

used primarily to depict the potential wave attack population. It is 

not utilized to determine structural failure. It was deemed the results 

are well within the level of accuracy for the analysis. 

070. For the without project condition, limits of wave attack were 

reanalyzed for each lO-year time period to reflect changes due to 

long-term erosion. This procedure was unnecessary for the with project 

condition since long-term erosion will be checked by an ongoing 

maintenance program. Since this analysis was performed on grids' of 

coastline rather than specific beach profiles, the impacts of recession 

were analyzed qualitatively based on the height and width of protective 

beach. Specific structures subject to wave·attack during the 25-year, 

laO-year and SaO-year storms were identified. 

071. The actual depth necessary for structural failure was calculated 

as described below. The purpose of segmenting the structures into the 

three wave zones was to avo.idprematurely failing structures. Failure 

of individual buildings is determined based on the depth of water 

surrounding the structure and its potential to sustain a specific 

breaking wave resulting in a force capable of causing structural 

failure. Since the ground slopes downward away from the ocean, it is 

conceivable that buildings in the third or fourth row of. structures will 

experience a greater depth of water than one closer to the ocean and 

under certain circumstances erroneously be assumed to fail. The reason 

it would be erroneous is that the frequency event being analyzed may not 

be capable of transmitting a wave that deep into the flood plain. 

198 
Therefore to mitigate against this potential problem, the three wave 

zones were delineated and structures identified in each zone. Therefore 

beyond the 2S-year wave zone, when analyzing a .less than 2S-year return 

frequency, no matter how deep the still water is around a building, if 

it is located beyond the 2S-year wave zone, the building was considered 

not to fail due to wave attack since the incoming ocean wave would be 

incapable of reaching the structure. 

D72. The evaluation considered four structure groups. Based on data 

obtained from a windshield survey, there exists 310 buildings in the 

1985 SOO-year wave zone excluding detached garages plus an additional 20 

structures associated with the Long Branch Pier. Exclusive of the Long 

Branch Pier, which is entirely supported on piles, only slightly more 

than 5% of the wave zone population is elevated on either piles or piers 

and thus does not reflect a significant portion of the population. A 

single masonry garden apartment was also excluded from the analysis 

because, with a "footprint" of 18,000 square feet it was nearly double 

the next largest building, and it was oriented with its narrow side 

toward the water further reducing its likelihood of wave failure. 

Because the potential for failure is somewhat different for pile supported structures, they were evaluated as a separate category even though 

they represent only a small portion of the population. Thus the wave 

zone structures were categorized as follows for this evaluation 

exclusive of the Long Branch Pier. 

% of Wave Zone 

Population Group Name 

83% Wood Frame Structures not elevated on 

piles or piers 

11% Masonry Structures not elevated on piles 

or piers 

3% Pile & Pier Supported Structures elevated 

less than or equal to 4 feet above grade 

3% Pile Supported Structures elevated more 

than 4 feet above grade 

Average 

Size 

40 x 63 

40 x 70 

60 x.61 

56 x S2 

D73. The Long Branch Pier wasexcluded'from the analysis because the 

implementation of a project would not appreciably alter its vulnerability because of its location. For wood frame structures, two beach 

clubs were also excluded because of their very large "footprint", the 

smaller of which being more than 50% greater than the next largest 

structure, making them outliers in the data base. Additionally, due to 

their size, total failure due to wave action is unrealistic. Damages to 

these larger structures did not assume total destruction of the 

build~ng. In general, the evaluation is very conservative since it 

assumes all connections have been properly designed and failure will not 

occur as a result of joint failure or material failure. In addition, 

199 
since wind loading will not be altered by project implementation, only 

wave forces were incorporated into the analysis. In reality, improper, 

connections and material failure are major causes of damage, however 

much more detailed structural information on individual buildings would 

be required to make this evaluation and without such information this 

approach yields a conservative estimate of damages. Each group of 

structures ~herefore was only analyzed for complete failure based on 

overturning or lateral displacement based on the average size structure 

for the category. The structural analysis followed procedures presented 

in the Army Corps of Engineers "Shore Protection Manual" and the FEMA 

manual "Elevating to the Wave Crest Level" and was premised on the basis 

that a wave greater than 78% of the water depth will break. 

074. Pile Supported Structures - There are only 18 pile-supported 

structures identified within the wave zone and one - pier-supported 

structure which was treated as pile supported. Ten of these are elevated 4 feet or less above the eXisting grade. The remainder range from 

6 feet to eleven feet above grade with the majority being a cabana 

complex at 10 feet above grade. Construction varies greatly between 

buildings but in general the structures with the shorter support system 

were utilizing the piles more so as a foundation support than as a means 

of elevating the structure. For this group an average above-ground pile 

length of three feet was used. For the pile-supported structures in 

excess of four feet the pile was oftentimes used to elevate the structur.e above the flood plain. These eight structures have a pile height 

ranging from six to eleven feet above the ground with seven of them 

being ten feet or higher. ThuS a height of ten feet was used for the 

analysis. For the longer piles, a pile diameter of twelve inches spaced 

ten feet on center was used. For the shorter piles an 8-inch pile was 

assumed with the same spacing. These values were selected based on 

general field observation. The analysis assumed the first two teet of 

sand would be unsupportive due to a combination of Liquifaction!Local 

Scour. 

075. No cross. bracing was assumed in the analysis based .on field 

observation of the majority of 10-foot piles and for the lower piles no 

cross braCing would be expected. The building code in New Jersey does 

not prescribe a minimum pile depth but rather sets a performance 

standard based on dead weight loads. This becomes dependent on soil 

types, existing grade elevations, etc. To simplify the analysis, the 

builder of a large percentage of these structures was contacted and 

reported using pile lengths of 30 feet. Using a pile length extending 

10 feet above grade and the average ground elevation of the structures, 

a pile invert elevation was established at -10.3 feet NGVD, which was 

considered to be typical for the area. From the aforementioned 

conditions, it was determined that for the short piles a still water 

depth of 4 feet would be capable of sustaining a large enough breaking 

wave to eause failure and for the larger piles a water depth of 4.5 feet 

could cause failure. 

076. Masonry Structures - The majority of the masonry structures are 

built on slab. For these structures, lateral displacement exerted by 

the wave action will cause failure when the still water elevation is 5.1 

feet above grade. 

200 
D77. Wood Frame Structures - These structures, which represent the vast 

majority of the population, are predominantly built on slab with some 

basements. For this analysis slab construction was considered. Failure 

was determined to occur due to lateral displacement at a still water 

depth of 4.2 feet. Failure of the wood frame structure occurred at a 

lesser depth than the masonry construction due to its smaller size and 

lesser unit weight. 

D78. Wave Runtip - In addition to structures subject to impact from a 

wave propagated across inundated land areas, some structures at an 

elevation above or beyond the limit of wave propagations are subject to 

equivalent forces from wave runup. 

D79. The limit of wave runup impact was determined for the 10, 25, 100 

. and 500 year frequency events at representative beach profiles as 

described in Appendix A. The horizontal limits of the runup zone 

reported the landward limit of a force capable of causing structural 

failure. Since the wood frame structures represent over BO percent of 

the wave .zone population, ·the lateral force necessary to displace this 

category was used to set the horizontal limit of runup for each 

frequency analyzed for each reach. Interpolation between the analyzed 

frequencies was complet~d graphically by plotting frequency against 

runup up distance. The ultimate determination of damage due to runup at 

any particular frequency event was then determined· by comparing the 

structures set back distance to the runup distance. If the set back 

equalled or was exceeded by the runup, it was assumed to fail. As in 

the case of breaking waves, total failure was not assumed for extremely 

large buildings. Wave attack for any structure was determined to be the 

lowest frequency event causing failure due to wave propagation or runup. 

Critical Damage 

DBO. As previously described, structures within the study area are 

exposed to storm damages from a number of possible mechanisms: 

o Long Term Erosion 

o Storm Recession 

o Inundation 

o Wave Action 

DBI. In order to move forward to Average Annual Damage Calculations, 

damages for each reach were summarized by frequency-damage over the 50 

year life of the project. This procedure was designed to eliminate the 

potential for double counting. Each one-foot stage of inundati.on was 

related to a frequency and that frequency was then utilized to evaluate 

the potential damage from each damage mechanism. To prevent double 

counting only the maximum damage to any single structure was reported 

for a specific frequency. As depicted in Figure D-B the "Critical 

Damage" can fluctuate from inundation to Storm Recession to Wave Attack 

for different frequency events. Thus, the sum of damages resulting from 

the individual damage mechanisms will far exceed the critical damage due 

to double counting. For display purposes, the damage associated with 

the individual mechanisms are based on a percentage of their summation 

201 
corrected to restated critical 4aaage. Furthermore, the analysis of .. cumulative 4aaage by reach for future years can vary as .egments of the 

population are removed from the data base e.nd loug term ero.sion 

increases the landward limit of 4aaage. 

082. To more accurately reflect future damages, local floodplain 

management and building practices were investigated to evaluate 

anticipated levels of protection for any Itructurel which are rebuilt 

after destruction by Itorm recession or wave attack. It was determined 

that future reconstruction of any building would tolerate no greater 

risk of 4amage from wave attack or storm recession than exhibited by 

current building practices. Any structure which would be closer to the 

future waterline than current building practices was aSlumed to not be 

rebuilt. Residential structures which are rebuilt were considered 

protected to the 2,.year event. This level of protection was arrived at 

by comparing the elevation criteria required by FIA to the results of 

the storm lurge model and taking into consideration that Itorm recession, and in most cases wave attack are not considered by FIA. Since 

the majority of commercial structures in the project area which 

currently do not meet FIA requirements are located in the Sea Bright 

business district and depend on street level access by clientele drawn 

to the area's recreation facilities. it was determined that the physical 

constraints of this high density ·curb front development and the negative 

economic impacts of raising the structure would result in busin.ess 

owners rebuilding with no increased level of protection. 

083. In order to account for these changing future conditions, the 

critical damage at each year and frequency was multiplied by the 

probability that the structure exists and is subject to damage at that 

frequency event. The probability of existence for each structure was 

calculated using the maximum probability of total damage from wave 

attack or storm recession for each year analyzed with straight line 

interpolation for the intervening years. 

084. To provide a comparison to historic storm surge and damage data. 

the existing condition critical damage for various frequency events was 

aggregated into a still water ocean stage vs. damage relationship. 

Although damage is presented in relation to stage to permit a comparison 

to hi.toric .torms. it should be ~oted that the damage associated with 

wave attack and recession were evaluated for the various storm 

frequencie. and thus, stage has merely been used as a lurrogate for 

dilplay purpoles. The 1985 condition Itage vs damage comparison 

developed utilizing this methodology is presented in Table 0-9. All 

damages related to flooding in the Shrewsbury River have been adjusted 

to the corresponding still water ocean Itage utilizing the combined 

hurricane and northeaster Stage-Frequency curves developed by CERC. 

Coaparilon of the predicted daiDages to t.he historicdaaage indicates 

concurrence with the Karch 1984 storm. Considering the impact of over 

20 years of shoreline erosion. intensive development, the regional 

increase in real estate value. and seavalldegradation to the point 

where a recurrence of the 1962 storm would result in total failure of 

202 

(Rev. Karch 1990) 
major .ections, the difference between damage. reported in Karch 1962 

and those predicted for 1985 conditions appear reasonable. In addition, 

the post Itorm reports utilized for historic damages are limited 

investigations which tend to underestimate the total damages. 

TABLE 1)-9 

SEA BiIGHT to OCEAN TOWNSHIP 

COHPARISON OF PREDICTED TO HISTORIC DAKAGE 

JUN! 1988 pnCE LEVEL 

Ocean Still Vater 

Stage 

(NGVD) 1 

Predicted 

Damage 

(Killions) 

1985 Conditions 

J1pdat~d 

Historical 

Damage 

NOTES: 

6 ft. 

6.4 ft. 2 

(Karch 1984) 

7.6 ft.' 

(Karch 1962) 

8 ft. 

10 ft. 

12 ft. 

$ 11.3 

18.8 

73.3 

9S.7 

177 .8 

252.1 

1. Ocean Still Vater Stage not including wave setup or runup. 

2. Data from -Post Storm Evaluation Karch 29, 1984 Northeaster.-

Stage is maximum recorded at Long Branch. N.J. 

3. Data from -ieport on Operation Five High~ •. Stage is maximum 

recorded at Sandy Hook, N.J. 

203 

(iev. Karch 1990) 
AVERAGE ANNUAL DAMAGES 

085. Utilizing the critical damage-frequency relationships, including 

adjustments for probability of existence, average annual damages were 

computed at 10 year increments using the HEC computer program "Expected 

Annual Damages" (EAD). For the structures in Reach 3, sample 

calculations of average annual residential damage for physical, emergency and lost income damage and increased residential contents damage 

(Affluence) are p~esented in Tables 0-10 and 0-11 respectively. Table 

0-12 summarizes the total equivalent annual flood damages for all the 

reaches in the study area. These damages are shown for existing conditions as well as conditions·· expected during the project life (1990-

2040). The methodology for estimating future conditions accounts for 

rebuilding of eXisting structures and future increases in the value of 

residential contents •. 

STORM REDUCTION BENEFITS 

086. Storm reduction benefits were calculated for the 14 reaches from 

1 to 11 including 6A and 6B, 8A and 8B and 9A and 9B as depicted on 

Figures 0-5 and 0-6. Storm reduction benefits from the proposed plans 

of improvement were estimated by evaluating damages with and without the 

proposed project and under existing and future conditions. The storm 

reduction benefits derived from the proposed project consist of: 

o Preventable .averag~ annual damages to buildings, roads, 

utilities .nd othe~ structures . 

o Reduced public emergency costs 

o Reduced maintenance costs 

087. Benefits are based on damage to existing development. Changes in 

future floodplain development considered in ehe analysis are limited to 

constraints on structure rebuilding as previously described and 

increased .residential content damage as described under affluence. 

Storm reduction benefits were derived from the computation of average 

annual flood damages resulting fr·om the maximum damage occurring for a 

specific return period when considering inundation, wave attack and 

storm recession. The without project Average Annual Damages are 

displayed in Table 0-12. The benefit analysis conducted over the 

50-year project life reflected a reduction in structure population due 

to long term erosion. Tables 0-13 through 0-15 provide a breakdown of 

the Storm Damage Reduction Benefits derived from building and 

infrastructures into its component parts for the alternative plans of 

improvements and various berm widths. 

204 
N 

o 

\J1 

TABLE 0-10 

REACH 3 AVERAGE ANNUAL DAMAGES 

(IN THOUSAOOS Of DOLLARS) 

* * * * * * * • • * • * • * * * * * • • • • • • * * • • * • • • • * * • • • * * • • • * • * * • • * • * 

* * * • * • • * • * • * • • • • • • * • • • • • * • * • • • • * * • * • • • • • • * * * * • • * * • * 

** EXPECTED ANNUAL FLOOD DAHAGE ** 

** fOR REACH 1· REACH 3.RES ** WITH PLAN 1. REACH 3.RES- EXISTING CONDITIONS 

** INPUT DATA YfARS • 1985 1990 2000 2010 2020 2030 2040 

** PERIOD OF ANALYSIS. 50 YEARS 

** DISCOUNT RATE 

** DAMAGE BASE 

DAMAGE. 

CATEGORIES 

• 8.6250 PERCENT 

• JUNE 1988 DOLLARS 

STUDY 

YEAR 

1985 

BASE 

YEAR 

1991 

••••••••••••• •• , DECADE YEARS 

10 20 30 

2000 2010 2020 

END OF EQUIVALE

40 50 PERIOD ANNUAL 

2030· 2040 2040 DAHAGE 

1 

2 

3 

PHYS 

EMER 

LOIN 

1310:44 

11S.10 

38.87 

1260.14 

111.98 

37.44 

1193.S0 

107.02 

3S.6O 

1132.19 

102.39 

33.84 

1080.79 

98.44 

32.86 

1037.22 

95.02 31.03 

999.85 

92.0S 

29.91 

999.8S 

92.0S 

29.91 

TOTAL 1465.02 1409.56 1336.12 1268.42 1212.09 1163.27 1121.81 1121.81 

1188.57 

106.61 

35.46 

1330.64 

* * * • * • * * * • • • • * * * * * • • * * • • * * * * • • • * • • * * * • • • * * * * * * * * * * • • 

• • • • * * • * * • * • • • • • • • • * • • • • • * • * • * • • * * • * • • • * * • • • * • * * * • • 
N 

0 

0-

TABlE 0-11 

REACH 3 AVERAGE ANNUAL DAMAGES 

RESIDENTIAL CONTENTS 

THOUSANDS OF DOLLARS) 

• • • • • * * • * • • • • • • • • • • • * * • • • • • • • • • • • • * • • • * * • • • • • * • • * * * • • * 

• • • * • • • * * * • * * • • * • • * • • • • • * • • • • * * • • • • • * • * * • • • • • • • • • • • * • • 

• * * * * * * • * • • * • • • • • * * * • * • • • • • • * • • • • * • • * * • • • • • • • • * * • • • • • • 

** EXPECTED ANNUAL FLOOD DAMAGE ** 

** FOR REACH 1 • ** WITH PLAN 1 • 

** INPUT DAtA YEARS · ** PERIOD OF ANALYSIS • 

** DISCOUNT RATE 

** DAMAGE BASE 

DAMAGE 

CATEGORIES 

1 CONT 

· 

· 

STUOY 

YEAR 

1985 

0.00 

REACH -3 

REACH -3 EXISTING CONDITIONS 

1985 1990 2000 2010 2020 2030 2040 

50 YEARS 

8.6250. PERCENT 

JUNE 1988 ODLLARS 

BASE 

YEAR 

1991 

•••.....••..•.... DECADE YEARS 

10 20 30 

2000 2010 2020 

64.22 123.59 168.24 208.10 

40 . 50 

2030 2040 

250.19 294.11 

END OF 

PERIOD 

2040 

294.11 

EQUIVALENT 

ANNUAL 

DAMAGE 

124.56 

TOTAL 0.00 64.22 1Z3.59 168.24 208.10 250.19 294.11 294.11 124.56 

• • • • • • • • * * * • • • • • • • * • • • • • • • * • • • * • • • * • • • * * • • • • • • * • * • * • • • 

* • • • - • • • • • • • • • • • • • • • • • * • • * * • * * • • • * • • • * * • • • • • • • • * * • * * • * 
N 

0 

..... 

TABLE D - 12 

SEABRIGHT TO OCEAN TOWNSHIP 

AVERAGE ANNUAL DAMAGE SUHHARY TABLE 

IIITHOUT PROJECT 

(JUNE 1988 PRICE LEVEL) 8 5f8% INTEREST RATE 

ECONOHIC REACH 

IIITHOUT PROJECT 

DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

DAMAGE IN THOUSANDS OF DOLL

1 2 3 4 

5789.1 54,361.351,484.1 52,913.9 

531.4 $143.6 5112.9 5123.7 

59.0 525.4 535.5 540.1 

5 

$296.4 

$10.5 

$2.5 

538

$$

BUILDINGS TOTAL (NO AFFLUENCE) 5835.5 54,536.351,632.4 $3,138.3 $309.3 $39

ADJUSTMENT FOR 

AFFLUENCE 

128.1 $41.0 $124.6 $188.3 $10.5 $

---------------*-------------------------------------------------------------------------------

BUILDINGS TOTAL (11/ AFFLUENCE) $864.2 $4.583.2 $1,151.0 $3,326.6 $319.8 $40

DAMAGE TO SEAWALLS $3,114.8 $0.0 $814.5 $468.0 $661.4 $DAMAGE TO ROADS AND $1.1 $23.3 $0.9 $4.0 $0.5 $30

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS $1.6 50.1 50.1 $1.0 $1.2 5

TOTAL IIITHOUT PROJECT 

AVERAGE ANNUAL DAHAGES 4613.6 4560.2 2508.6 3611.4 918.4 70

(NO AFFLUENCE) 

TOTAL WITHOUT PROJECT 

AVERAGE ANNUAL DAMAGES 4642.3 4601.2 2633.1 3799.7 988.8 11

(11/ AFFLUENCE) 
N 

0 

00 

TABLE 0 - 12 

SEABRIGHT TO OCEAN TOUNSHIP 

AVERAGE ANNUAL DAMAGE SUMMARY TABLE 

WITHOUT PROJECT 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH. 

WITHOUT PROJECT 

DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

8A 

11,135.0 

129.4 

$3.6 

8B 

1213.7 

15.1 10.1 

DAMAGE IN THOUSANDS OF DOLLAR

9A 

1481.3 

165.6 

110.5 

98 

137.4 

11.0 10.2 

10 

198.0 

12.1 

$0.2 

1

1169.3 

$3.6 

11.4 

BUILDINGS TOTAL (NO AFFLUENCE)11,168.0 1219.0 1557.4 138.5 1100.3 S174.2 

ADJUSTMENT FOR 143.6 11.1 198.0 11.6 14.4 111.

AFFLUENCE 

--------------------------------------------------------------------------------------------------

BUILDINGS TOTAL (WI AFFLUENCE)11,211.5 S220.1 1655.4 $40.1 $104.7 S185.

DAMAGE TO SEAWALLS 10.0 10.0 10.0 169.2 $0.0 SO.O DAMAGE TO ROADS AND 120.4 10.0 1157.0 0.0 31.9 1186.1 

INfRASTRUCTURE 

PUBLIC EMERGENCY COSTS 10.6 11.1 11.4 0.2 1.1 10.6 

TOTAL WITHOUT PROJECT 

AVERAGE ANNUAL DAMAGES 1188.9 220.0 715.8 107.9 133.3 360.9 

(NO AfFLUENCE) 

TOTAL WITHOUT PROJECT 

AVERAGE ANNUAl DAMAGES 1232.5 221.1 813.8 109.5 137.7 372.5 

(WI AffLUENCE) 
N 

0 

\0 

TABLE 0 - 13 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS SUMMARY TABLE - 50 FOOT BERM 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOHIC REACH 

50 FOOT PROJECT 

BENEFITS TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOHE 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

1 2 

"22.6 '2.196.8 

'8.3 117.3 

13.0 10.0 

FI LL ONLY PLAN 

BENEFITS IN THOUSANDS OF 

3 4 

1810.9 ".952.1 

171.2 186.0 

'24.5 132.7 

5 

$129.3 

12.4 10.2 

1133.9 '2.214.1 '906.6 '2.070.7 "32.0 

U.8 $3.7 $75.7 $173.6 '2.8 

----------------.------------_.-------------------_.----------------------------.-----------

BUILDING TOTAL (W/ AFFLUENCE) 

REDUCED DAMAGE TO SEAWALLS REDUCED DAMAGE TO ROADS ANO 

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

REDUCED MAINTENANCE COSTS 

fOR SEAIIALL 

TOTAL STORM REDUCTION BENEFITS 

(NO 

TOTAL STORM REDUCTION BENEFITS 

(11/ AffLUENCE) 

$137.1 $2.217.8 $982.3 $2.244.3 '134.8 

13.013.5 $0.0 .502.6 $211.1 '383.5 

ILl 122.6 '0.1 $4.0 10.5 

10.3 $0.4 '0.4 10.7 $0.5 

"91.4 '57.3 '85.3 122.0 '27.0 

13.346.7 '2.294.4 11.495.6 12.374.6 '543.4 

'3.350.5 12.298.111.571.3 12.548.1 $5106.2 
N 

...... 

0 

TABlE D - 13 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS 

SUllllARY TABlE - 50 FOOT BERN 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

50 FOOT PROJECT 

BENEF ITS TO BUILDINGS 

PHYSiCAl 

EMERGENCY 

LOST INCOItE . 

8A 

51.121.1 

529.2 

$3.5 

88 

5213.6 

55.1 

SO.1 

F ILL ONLY PLAN 

BENEFITS IN THOUSANDS OF DO

9A 

5419.7 

163.5 

510.2 

9B 

512.5 

10.2 10.0 

10 

171.0 

$1.5 

50.2 

11

SS

----------------------.-------------------------------------------------------------------------

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT fOR 

AFFLUENCE 

51.153.8 5218.8 5493.4 

543.1 51.1 595.0 

512.8 

51.3 

578.7 51

$3.6 5

-----------------------------------------------------------------------------.---.--------------

BUILDING TOTAL (WI AFFLUENCE) 

REDUCED DAMAGE TO SEAWALLS REDUCED DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

REDUCED MAINTENANCE COSTS 

fOR SEAWALL 

TOTAL STORM REDUCTION BENEfiTS 

(NO 

TOTAL STORM REDUCTION BENEFITS 

(WI AFFLUENCE) 

51.196.9 5219.9 1588.4 

SO.O 50.0 50.0 

$17.6 50.0 $143.2 

SO.6 $1.1 51.2 

10.0 50.0 50.0 

51.172.0 5219.9 1637.7 

51.215.1 5221.0 5732.7 

514.1 582.2 51

$43.4 50.0 S

50.0 524.7 116

50.1 50.9 SO

SO.O 50.0 S

556.2 5104.3 517

557.6 5107.9 517
N 

...... 

...... 

TABlE 0 - 13A 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEfITS 

SUMMARY TABLE - 50 FOOT BERM 

(JUNE 1988 PRICE lEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

50 fOOT PROJECT 

BENEfITS TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOHE 

1 2 

1122.6 12,196.8 

18.3 117.3 

13.0 10.0 

BEACH fILL WITH AUTHORIZE

BENEfITS IN THOUSANDS 

3 4 

1810.951,952.1 

571.2 586.0 

524.5 132.7 

5 

1129.3 

S2.4 

50.2 

-----------------------------------------------------------------------------------------

BUILDING TOTAL (NO AFfLUENCE) 5133.912,214.1 5906.6Ii,070.7 S132.0 

ADJUSTMENT fOR 

AffLUENCE 

S3.8 13.7 175.7 S173.6 12.8 

--------------------.-----------------------------------.--------------------------------

BUILDING TOTAL (WI AffLUENCE) 

REDUCED DAMAGE TO SEAWALLS 

REDUCED DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EHERGENCY COSTS 

REDUCED MAINTENANCE COSTS 

FOR SEAWALL 

TOTAL STORM REDUCTION BENEfiTS 

(NO AFFLUENCE) 

TOTAL STORH REDUCTION BENEfiTS 

(III AffLUENCE) 

1137.7 52,217.8 S982.3 52,244.3 5134.8 

Sl,013.5 SO.O 5502.6 5277.1 S383.S 

S1.7 522.6 SO.7 54.0 SO.5 

SO.3 SO.4 10.4 SO.7 $0.5 

1197.4 157.3 585.3 122.0 527.0 

53,3'6.7 52,294.4 51,495.6S2,374.6 5543.4 

53,350.5 12,298.1 11,571.3 12,548.1 5546.2 
N 

I-' 

N 

TAllLE D - 13A 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS 

SUtutARY TAllLE - 50 FOOT BEM 

(JUNE 1988 PRICE lEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

50 FOOT PROJECT 

BENEFITS TO BUILDINGS 

PHYSICAl 

EMERGENCY 

LOST INCOME 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

SA 

$1.121.1 

$29.2 

$3.5 

88 

5213.6 

55.1 

$0.1 

BEACH FILL WITH AUTHORIZED GRO

BENEF ITS IN THOUSANDS OF D

9A 

$419.7 

563.5 510.2 

98 

512.5 

$0.2 

50.0 

10 

571.0 

51.5 

50.2 

5

5

S

51.153.8 5218.8 5493.4 512.8 578.7 5

543.1 51.1 595.0 S1.3 $3.6 5

.----------------.---.--------------------.----------.-----.-----------------------------------

BUILDING TOTAl (WI AFFLUENCE) 

REDUCED DAMAGE TO SEAWALLS REDUCED DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

REDUCED "AINTENANCE COSTS 

FOR SEAWALL 

TOTAL STORM REDUCTION BENEFITS 

(NO AFFLUENCE) 

TOTAL STOM REDUCTION BENEFITS 

(WI AFFLUENCE) 

51.196.9 5219.9 5588.4 

$0.0 $0.0 50.0 

517.6 $0.0 5143.2 

$0.6 51.1 51.2 

50.0 $0.0 $0.0 

51,172.0 5219.9 5637.7 

51.215.1 5221.0 5732.7 

514.1 582.2 $

543.4 50.0 $

$0.0 524.7 516

$0.1 50.9 1

$0.0 50.0 1

556.2 5104.3 517

557.6 5107.9 517
N 

...... 

w 

TABlE D - 138 

SEABRiGHT TO OCEAN TOIIIISHIP 

STORN REDUCTION BENEfITS 

SUIIWlY TAllLE - 50 fOOT BElli 

(JUNE 1988 PRICE LEVEL) 8 5/81 INTEREST RATE 

ECONOMIC REACH 

50 FOOT PROJECT 

BENEFITS TO BUILDINGS 

PHYSICAl 

EMERGENCY 

lOST INCOII£ 

BUILDING TOTAL (110 AffLUENCE) 

ADJUSTIIENT fOR 

AffLUENCE 

1 2 

$122.6 $2.196.8 

$8.3 $17.3 

53.0 $0.0 

BEACH fill IIITH UPDATED 

BENEfITS IN THOUSANDS Of 

3 4 

5810.9 $1,952.1 

$71.2 $86.0 

124.5 $32.7 

5 

5129.3 

$2.4 $0.2 

$133.9 $2.214.1 5906.652,070.7 "32.0 

'3.8 53.7 575.7 5173.6 $2.8 

--------------------------------------.--------------.--------------------------------------

BUILDING TOTAL (II, AfFWENCE) 

REDUCED IWIAGE TO SEAIlALLS REDUCED IWIAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC E"ERGENCY COSTS 

REDUCED COSTS 

FOR SEA"ALL 

TOTAL STORN REDUCTION BENEfITS 

(NO AFFLUENCE) 

TOTAL STORN REDUCTION BENEfITS 

('" AFFLUENCE) 

5137.7 52.217 .• 8 5982.3 52.244.3 5134.8 

53.013.5 $0.0 5502.6 '277.1 5383.5 

51.7 522.6 SO.7 $4.0 50.5 

$0.3 $0.4 $0.4 $0.7 $0.5 

$197.4 557.3 585.3 '22.0 '27.0 

'3,346.7 12,294.4 .'.495.6 '2,374.6 554].4 

53,350.5 '2.298.1 .'.571.3 '2,548.1 5546.2 
N 

.po 

TABLE D - 138 

SEABRIGHT TO OCEAN TOWNSHIP 

STORK REDUCTION BENEFITS 

SUHMARY TABLE - 50 FOOT BERH 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

50 fOOT PROJECT 

BENEfITS TO BUILDINGS 

PHYSICAL 

EHERGENCY 

LOSTINCOHE 

BUILDING TOTAL (NO AFfLUENCE) 

SA 

51,121.1 

S29.2 

$3;5 

sa 

5213.6 

S5.1 

50.1 

BEACH FILL WITH UPDATED G

BENEFITS IN THOUSANDS OF D

9A 

S419.7 

S63.5 S10.2 

9B 

512.5 

SO.2 

SO.O 

10 

S77.0 

S1.5 

SO.2 

S

51,153.8 S218.8 5493.4 512.8 S78.7 5

ADJUSTHENT fOR 

AFFLUENCE 

S43.1 S1.1 595.0 S1.3 53.6 

---------.-------------------------------------------------------------------------------------

BUILDING TOTAL (WI AFfLUENCE) 

REDUCED DAMAGE TO SEAWALLS 

REDUCED DAMAGE TO ROADS AND 

INfRASTRUCTURE 

PUBLIC EHERGENCY COSTS 

REDUCED MAINTENANCE COSTS. 

FOR SEAWALL 

TOTAL STORH REDUCTION BENEfiTS 

(NO AffLUENCE) 

TOTAL STORM REDUCTION BENEfITS 

(WI AffLUENCE) 

S1,196.9 5219.9 S588.4 

50.0 SO.O 50.0 

517.6 SO.O S143.2 

50.6 S1.1 51.2 

SO.O SO.O 50.0 

51,172.0 5219.9 S637.7 51.215.1 S221.0 S732.7 

514.1 582.2 . S

S43.4 SO.O 

SO.O S24.7 S1

50.1 50.9 

SO.O 50.0 

S56.2 5104.3 S1

S57.6 S107.9 S1
N 

...... 

VI 

TABLE D - 14 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS 

SUHHARY TABLE - 100 FOOT BERM 

(JUNE 1988 PRICE LEVEL) 8 5/8l INTEREST RATE 

ECONOMIC REACH 

100 FOOT PROJECT 

REDUCED DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

FILL ONLY 

BENEFITS IN THOUSANDS O

1 2 3 4 

5352.9 52,551.7 51,112.3 52,103.2 

515.9 554.4 588.1 594.0 

54.5 54.8 528.2 533.8 

5 

5220.7 

56.8 51.6 

5373.3 52,610.9 51,228.6 52,231.0 5229.1 

514.2 59.6 587.7 5164.3 56.9 

--------------.----------------------------------------------------------------------------

BUILDING TOTAL (WI AFFLUENCE) 

REDUCED DAMAGE TO SEAWALLS REDUCED DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

REDUCED COSTS FOR SEAL/ALL 

TOTAL STORM REDUCTION BENEFITS 

(NO AFFLUENCE) 

TOTAL STORM REDUCTION BENEFITS 

(WI AFFLUEMCE) 

5387.5 52,620.5 51.316.2 52.395.3 5236.0 

53.628.5 50.0 5802.2 5419.1 5610.9 

51.7 523.2 50.8 54.0 SO.5 

50.7 SO.4 SO.5 50.7 50.9 

5197.4 557.3 185.3 522.0 527.0 

14.201.6 52,691.8 52.117;4 52.676.9 5868.3 

54.215.852.701.4 52.205.1 52.841.2 1875.3 
N 

I-' 

0-

TAILE D - 14 

SEAlRIGHT TO OCEAN TOWNSHIP 

STORH REDUCTION BENEFITS 

StlHMARY TAILE - 100 FOOT 8£l1li 

(JUHE 1988 PRICE LEVEL) 8 5/1" INTEREST RATE 

ECOHOIIIC REACH 

100 FOOT PROJECT 

REOUCED.OAHAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

fiLL ONLY PLAN 

IENEF ITS IN THOUSANDS OF OOL

SA 

11.131.6 

529.2 

U.S 

88 

$213.7 

55.1 

SO.1 

9A 

5478.0 

565.5 

110.5 

11.164.3 1219.0 5554.0 

543.4 51 .• 1 597.9 

98 

36.9 

0.9 

0.2 

138.0 

11.6 

10 

77.0 

1.5 

0.2 

178.7 

1.5 

145

SO

10

545

16

BUILDING TOTAL (WI AFFLUENCE) 

REDUCED DAMAGE TO SEAWALLS REDUCED DAMAGE TO ROADS AND 

INFRASTRUCTURE .. 

PUBLIC EMERGENCY COSTS 

REDUCED MAINTENANCE COSTS 

fOR SEAVALL 

TOTAL STOIIII REDUCTION BENEfITS 

(NO AffLUENCE) 

TOTAL STORM REDUCTION BENEFITS 

(WI AfFLUeNCE) 

51.207.7 1220.1 5651.9 

SO.O 50.0 50.0 

120.3 SO.O 1156.6 

SO.6 51.1 51.4 

SO.O 50.0 SO.O 

11,185.2 1220.0 1712.0 

11,228.7 $221.1 1809.9 

139.6 182.2 55159.7 0.0 10

SO.O 28.3 $163

50.2 0.9 SO

10.0 10.0 50

597.9 5107.9 5209

199.4 5111.4 5215
N 

.... 

...... 

TABLE D - 14A 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS SUHltARY TABLE - 100 FOOT BEM 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

100 FOOT PROJECT 

REDUCED DAMAGE TO BUILDJaGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

BUilDING TOTAL (NO AffLUENCE) 

ADJUSTMENT fOR 

AFfLUENCE 

BEACH FILL IIITH AUTHORIZ

BENEfiTS IN THOUSANDS Of 

1 2 3 4 

5352.952.551.751,112.352.103.2 

$15.9 $54.4 $88.1 $94.0 

54.5 54.8 $28.2 533.8, 

5 

5220.7 

56.8 

51.6 

5313.3 52.610.9 51.228.6 12.231.0 '229.1 

$14.2 $9.6 581.1 $164.3 '6.9 

---------------------------------------.-----------------------------------.-.-------------.

BUILDING TOTAL (III AfFLUENCE) 1387.5 52,620.5 51,316.2 '2.395.3 '236.0 

REDUCED DAMAGE TO SEAIIALLS $3.628.5 SO.O '802.2 '419.1 $610.9 REDUCED DAMAGE TO ROADS AND 11.1 '23.2 SO.8 $4.0 '0.5 

INfRASTRUCTuRE 

PUBLIC EMERGENCY COSTS 50.1 $0.4 SO.5 SO.l 50.9 REDUCED MAINTENANCE COSTS 5191.4 557.3 $85.3 '22.0 $21.0 

fOR SEAIIAlL 

TOTAL STORN REDUCTION BENEfiTS 

(NO AffLUENCE) 

TOJAL STORM aEDUCTlON BENEFITS 

<III AffLUENCE) 

'4.201.6 52.691.8 12.111.4 52.616.9 5868.3 

14.215.8 12.101.4 52.205.1 $2.841.2 5815.3 
N 

..... 

00 

TABlE D - 14A 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS 

SUIUIARY TABlE - 100 FOOT BERM 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOfIIC REACH 

100 FOOT PROJECT 

REDUCED DAIIAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

BUILDING TOTAL (NO AFFLUENCE) 

SA 

51,131.6 

529.2 

53.5 

51,164.3 

8B 

5213.7 

15.1 

10.1 

1219.0 

BEACH FILL WITH AUTHORIZED G

BENEFITS IN THOUSANDS OF DOL

9A 

1478.0 

565.5 510.5 

1554.0 

9B 

536.9 

10.9 

SO;2 

138.0 

10 

177.0 

11.5 10.2 

178.7 

145

SOSO

545

ADJUSTMENT FOR 543.4 11.1 197.9 11.6 13.5 56

AFFLUENCE 

------------------------------------------------------------------------------------------------

,cBUILDING TOTAL (WI AFFLUENCE) 

.EDUCED DAMAGE TO SEAWALLS 

REDUCED DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

REDUCED IlAINTENANCE COSTS FOR SEAWALL 

TOTAL STORM REDUCTION BENEFITS 

(NO AFFLUENCE) 

TOTAL STORM REDUCTION BENEFITS 

(WI AFFLUENCE) 

51,207.7 1220.1 1651.9 

10.0 SO.O 10.Q 

120.3 10.0 1156.6 

10.6 11.1 51.4 

10.0 10.0 $0.0 

51,185.2 1220.0 5712.0 

51,228.7 5221.1 18()9.9 

139.6 182.2 551

159.7 SO.O $0

$0.0 528.3 1163$0.2 50.9 $0

10.0 SO.O SO

597.9 5107.9 5209

599.4 1111.4 1215
N 

..... 

\0 

TABLE D - 14B 

SEABRIGHT TO OCEAN TOWNSHIP 

STORK REDUCTION BENEFITS 

SUMARY TABLE - 100 FOOT BERK 

(JUHE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOHIC REACH 

100 fOOT PROJECT 

REDUCED DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST JNCOHE 

BEACH FILL WITH UPDATED 

BENEFITS IN THOUSANDS OF 

1 2 3 4 

$352.9 $2,551.7 $1,112.3 12,103.2 

$15.9 $54.4 $88.1 $94.0 

14.5 $4.8 128.2 133.8 

5 

1220.7 

16.8 

11.6 

$

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

1373.3 $2.610.9 $1,228.6 12,231.0 1229.1 $

$14.2 19.6 187.7 1164.3 16.9 

------------.--------------------------------------------------------------------------------

BUILDING TOTAL (WI AFFLUENCE) 

REDUCED DAMAGE TO SEAWALLS 

REDUCED DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

REDUCED MAINTENANCE COSTS 

FOR SEAWALL 

TOTAL STORM REDUCTION 8ENEFITS 

{NO AFFLUENCE) 

TOTAL STORK REDUCTION BENEFITS 

(WI AFFlUENCE) 

1387.5 $2.620.5 11,316.212 •. 395.3 1236.0 1

$3,628.5 10.0 1802.2 $419.1 1610.9 

11.7 123.2 10.8 14.0 SO.5 1

10.7 10.4 10.5 10.7 10.9 

S197.4 S57.3 185.3 S22.0 S2.7.0 

S4,201.6 S2,691.8 12.117.4 S2,676.9 1868.3 1

14.215.812,701.4 S2,205.1 12.841.2 S875.3 1
N 

N 

0 

TABlE D - '48 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS 

SUfItIARY TABLE - 100 FOOT BERM 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOlnc REACH 

100 FOOT PROJECT 

REDUCED DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOIIE 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

SA 

51,131.6 

129.2 

13.5 

8B 

5213.7 

15.1 

SO., 

BEACH FILL WITH UPDATED GRO

BENEFITS IN THOUSANDS OF DOL

9A 

5478.0 

165.5 

510.5 

9B 

536.9 

SO.9 

SO.2 

10 

177.0 

11.5 

10.2 

145

SOSO

11,164.3 5219.0 1554.0 138.0 178.7 145

543.4 11.1 197.9 11.6 13.5 16

------------------------------------------------------------------------------------------------

1JUILDING TOTAL (WI AFFLUENCE) 

REDUCED DAHAGE TO SEAWALLS REDUCED DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EHERGENCY COSTS 

REDUCED HAINTENANCE COSTS 

FOR SEAWALL 

TOTAL STORM REDUCTION BENEFITS 

(NO AFfLUENCE) 

TOTAL STORM REDUCTION BENEFITS 

(WI AffLUENCE) 

11,207.7 5220.1- 1651.9 539.6 582.2 151

SO.O SO.O SO.O 559.7 SO.O SO

120.3 SO.O 1156.6 SO.O 128.3 1163

SO.6 11.1 11.4 10.2 50.9 SO

SO.O SO.O SO.O SO.O 10.0 10

11,185.2 1220.0 1712.0 597.9 5107.9 5209

11,228.7 1221.1 1809.9 599.4 5111.4 1215
N 

N 

..... 

TABLE D - 15 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS 

SUHHARY TABLE - 150 FOOT BERH 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

150 FOOT PROJECT 

REDUCED DAHAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOItf 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTHENT FOR 

AFFLUENCE 

FI LL ONLY PLAN 

BENEFITS IN THOUSANDS OF D

1 2 3 4 

$504.4 $2,627.9 $1,254.6 $2,228.1 

$20.4 $55.7 $95.4 $100.9 

$5.1 $4.9 $28.8 $34.6 

5 

$257.8 

$8.1 $1.8 

$3

S529.9 S2,688.4 $1,378.8 S2,363.6 $267.7 $3

S19.5 $10.5 $110.9 S114.7 S8.4 

----------------------------------------------------------------------------------------------

BUILDING TOTAL (Y/ AFFLUENCE) 

REDUCED DAMAGE TO SEAYAlLS 

REDUCED DAHAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EHERGENCY COSTS 

REDUCED HAINTENANCE COSTS FOR SEAIIALl 

TOTAL STOR" REDUCTION BENEFITS 

(NO AffLUENCE) 

TOTAL STORM REDUCTION BENEFITS 

(W/ AffLUENCE) 

S549.3 $2,698.9 $1,489.1 S2,538.3 S276.1 13

$3,774.8 $0.0 S874.5 S468.0 $667.4 

$1.7 $23.3 SO.9 $4.0 SO.5 $3

$1.0 SO.4 SO.6 SO.8 S1.O 

$197.4 S57.3 ' $85.3 $22.0 S27.O 

S4,504.8 S2,769.4 $2,340.1 S2,858.4 S963.6 S6

$4,524.2 S2,779.9 $2,451.0 S3,033.1 S971.9 S6
N 

N N 

TAllLE D - 15 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BENEFITS SUMMARY TABLE - 150 FOOT BERM 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

150 FOOT PROJECT 

REDUCED O4KA6E TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUST"ENT FOR 

AFFLUENCE 

FILL ONlY PlAN 

BENEFITS IN THOUSANDS Of DO

SA 

51,131.7 

529.2 

13.5 

8B 

5213.7 

55.1 50.1 

9A 

5480.5 

565.6 510.5 

51,164.4 S219.0S556.6 

S43.4 51.1 S98.0 

9B 

37.4 

1.0 

0.2 

S38.5 

51.6 

10 

577.0 

51.5 

$0.2 

S78.7 

0.6 

54

5

5

S4

5

BUILDING TOTAL (W/ AFFLUENCE) 51,207.9 5220.1 5654.6 $40.1 582.2 15

REDUCED DAKA6E TO SEAWALLS 50.0 50.0 50.0 569.2 SO.O SREDUCED DAKA6E TO ROADS AND 5ZO.4 50.0 5157.0 SO.O 531.6 116

INfRASTRUCTURE 

PUBLIC E"ERGENCY COSTS 50.6 $1.1 51.4 50.2 $0.9 5

REDUCED KAINTENANCE COSTS 50.0 50.0 50.0 50.0 50.0 S

FOR SEAWALL 

-----------------------------------------------------------------------------------------------

TOTAL STORM REDUCTION BENEFITS 

(NO AFFLUENCE) 

TOTAL STORM REDUCTION BENEFITS 

tV/AFFLUENCE) 

51,185.4 5220.0 5715.0 5107.9 5111.1 521

11,221.8S221.15813.0 5109.5 5114.7 521
N 

N 

w 

TABLE 0 - 15A 

SEABRIGHT TO OCEAN TOWNSHIP 

STORH REDUCTION BENEFITS 

SUMMARY TABLE - 150 FOOT BERH 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC ·REACH 

150 FOOT !,ROJECT 

REDUCED DAMAGE TO BUILDINGS 

PHYSICAL 

EtlERGENCY 

LOST INCOME 

BEACH FILL WITH AUTHORIZE

BENEFITS IN THOUSANDS OF 

1 2 3 4 

5504.4 $2,627.9 $1,25.4.6 $2,228.1 

520.4 555.7 595.4 5100.9 

55.1 54.9 528.8 534.6 

5 

$257.8 

58.1 

51.8 

$

---------------------------------------------------------------------------------------------

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

5529.9 52,688.4 51,378.8 52,363.6 5267.1 5

$19.5 510.5 5110.9 5174.1 5B.4 

--.---------.--------------------------------------------------------------------------------

BUILDING TOTAL (WI AFFLUENCE) 5549.3 $2,69B.9 51,489.7 52,538.3 5276.1 5

REDUCED DAMAGE TO SEAWALLS 53,774.8 50.0 5874.5 5468.0 5667.4 

REDUCED DAMAGE TO ROADS AND $1.7 523.3 $0.9 14.0 50.5 5

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS $1.0 50.4 $0.6 50.8 51.0 

REDUCED MAINTENANCE COSTS $197.4 557.3 585.3 522.0 527.0 

FOR SEAWALL 

>---------------------------------------------------------------------------------------------

TOTAL STORH REDUCTION BENEfITS 

. (NO AFFLUENCE) 

TOTAL STORM REDUCTION BENEflTS 

(WI AFFLUENCE) 

$4,504.8 $2,769.4 52,340.1 52,858.4 $963.6 $

54,524.2 52,179.9 52,451.0 53,033.1 5911.9 5
N 

N 

.i:-

TABLE D - 1SA 

sEABRIGHT TO OCEAN TOUNSHIP 

STORM REDUCTION BENEfiTS 

SUlllARY TABLE - 150 fOOT BERM 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

150 fOOT PROJECT 

REDUCED DAHAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

BUILDING TOTAL. (NO AFfLUENCE) 

SA 

11,131.7 

129.2 

U.S 

11,164.4 

8B 

$213.7 

$5.1 

10.1 

$219.0 

BEAOH fILL UITH AUTHORIZED G

BENEfITS IN THOUSANDS Of OOL

9A 

$480.5 

165.6 

110.5 

1556.6 

9S 

Ul.4 

11.0 10.2 

138.5 

10 

171.0 

11.5 

10.2 

$78.1 

$46

10

SO

146

ADJUSTMENT fOR 143.4 st.1 198.0 $1.6 U.6 16

AfFLUENCE 

-------------------------------------------------------------------------------------------------

BUILblNG TOTAL CUI AfFLUENCE) 

REDUCED DAMAGE TO SEAWALLS 

REDUCED' DAMAGE TO ROADS AND 

INfRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

REDUCED MAINTENANCE COSTS 

FOR SEAWALL 

TOTAL STORM REDUCTION BENEFITS 

(NO AFfLUENCE) 

TOTAL STORM REDUCTION. BENEFITS 

(W/ AffLUENCE) 

11,201.9 1220 •. 1 1654.6 140.1 182.2 $52

10.0 10.0 10.0 169.2 10.0 10

120.4 SO.O 1151.0 10.0 131.6 $164

10.6 $1.1 $1.4 10.2 10.9 10

10.0 10.0 10.0 10.0 10.0 10

$1,185.4 $220.0 1115.0 1101.9 1111.1 1211

$1,228.8 $221.1 $813.0 $109.5 $114.,1 $217
N 

N 

VI 

TABlE D - 158 

SEABRIGHT TO OCEAN TOWNSHIP 

STORM REDUCTION BEMEflTS 

SUHHARY TABLE - 150 fOOT 8ERM 

(JUNE 1988 PRICE LEVEL) a 5j8X INTEREST RATE 

ECOHOKIC REACH 

150 fOOT PROJECT 

REDUCED DAMAGE TO BUILDINGS 

PHYSICAL 

EHERGENCY 

LOST 

BEACH fILL WITH UPDATED G

BENEf ITS IN THOUSANDS Of D

1 2 3 4 

1504.4 12.627.911.254.612,228.1 

lZO.4 155.7 195.4 1100.9 

15.1 14.9 128.8 134.6 

5 

1257.8 

$8.t 

11.8 

1

----._-----------------.---------------------.-----.------------------------------------------

BUILDING TOTAL (NO AffLUENCE) 

ADJUSTMNT fOR 

AffLUENCE 

BUILDING TOTAL (VI AffLUENCE) 

REDUCED DAMAGE .TO SEAWALLS 

REDUCED DAMAGE TO ROADS ·AND 

INFRASTRUCTURE 

PUBLIC "EHERGENCY COSTS 

REDUCED MAINTENANCE COSTS 

FOR SEAIIALL 

1529.9 12,688.4 11.378.812.363.6 1267.7 13

119.5 110.5 1110.9 1174.7 18.4 

1549.3 12.698.9 11,489.7 12,538.3 1276.1 13

13,774.8 10.0 1874.5 1468.0 1667.4 

n.7 $23.3 10.9 $4.0 SO.5 13

1';0 SO.4 10.6 10.8 $1.0 

5197.4 157.3 585.3 $22.0 127.0 

TOTAL STORM REDUCTION BENEFITS 14,504.8 12,769.4 $2,340.1 12,858.4 5963.6 $6

(NO· AffLUENCE) 

TOTAL STORM REDUCTl0III8ENEftTS $4.524.2 52,779.9 52,451.0 13,033.1 $971.9 $6

(III AffLUENCE) 
N 

N 

0-

TABLE P - 158 

SEAB'UGHT TO OCEAN TOWNSHIP 

STORM REDUCTION 8ENEFITS SUHHARY TABLE - 150 FOOT BEM 

(JUNE 1988 PRICE LEVEL) 8 5/81 INTEREST RATE 

ECOHOHIC REACH 

150 FOOT PROJECT 

REOUCED DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOftE 

BUILDING TOTAL (NO AffLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

SA 

11,131.7 

529.2 

13.5 

88 

5213.7 

55.1 

10.1 

8EACH FILL UITH UPDATED GROIN

8ENEFITS IN THOUSANDS OF DOLL

9A 

$480.5 

165.6 

110.5 

9B 

137.4 

11.0 

10.2 

10 

177.0 

U.5 

10.2 

1

$46.2 

10.5 

10.1 

11,164.4 1219.0 1556.6 138.5 178.7 $46.8 

143.4 11.1 198.0 11.6 $3.6 16.0 

-----------------------------------------------------------------.------.--------_.--------------

BUILDING TOTAL (loll AFFLUENCE) 

REDUCED DAMAGE TO SEAUALLS REDUCED DAMAGE TO ROADS AND 

INfRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

REOUCED MAINTENANCE COSTS 

FOR SEAWALL 

TOTAL STORM REDUCTION BENEFITS 

(NO AffLUENCE) 

TOTAL STORM REDUCTION BENEFITS 

(UI AFFLUENCE) 

11,207.9 1220.1 1654.6 140.1 182.2 152.8 

10.0 10.0 10.0 169.2 10.0 10.0 

120.4 10.0 1157.0 10.0 131.6 1164.3 

10.6 11.1 $1.4 10.2 10.9 $0.2 

10.0 10.0 50.0 10.0 10.0 10.0 

11,185.4 5220.0 5715.0 $107.9 $111.1 1211.2 11.228.8 1221.1 1813.0 5109.5 5114.7 5217.2 
D88. Residual damages that are not prevented by projects at the 

authorized berm height have also peen calculated and include residual 

ocean flooding as well as continued flooding from the Shrewsbury River. 

Tables D-16 through D-18 display the Residual Damages. 

D89. Affluence. Over time, the value of homeowner's possessions may be 

expected to increase as their personal income grows. Therefore, when 

estimates of damage are made, their growth in the value of damageable 

items must be taken into account. 

D90. Growth in per capita income in the storm damage area bas been 

projected to increase at the same rate as that of per capita income for 

the State of New Jersey of which the project is a part. Per capita 

income projections for New Jersey have been obtained from the 1985 OBERS 

BEA Regional Projections prepared by the U.S. Departm~nt of Commerce. 

D91. Based on site specific analysis, the current value of contents 

susceptible to damage was estimated to be 28% of the structure value. 

The contents value was allowed to grow at the same rat~ as per capita 

income, with the limitation that contents value would not exceed 75% of 

structure value. Factors for growth in content value were calculated 

for each 10-year period and the residential content damage in each year 

analyzed, was adjusted by the appropriate growth factor. Average Annual 

Damage was then calculated for each year and the present value of 

damages determined. Affluence factors are displayed in Table D-19. 

Application of the affluence factor increases the Existing Condition 

Average Annual Damages 2.5 percent. 

D92. Sea Wall Damase. Damage to the seawall as indicated in Tables 

D-12 through D-18 was based on failure of the seawall due to a 

combination of recession and wave attack causing displacement of the 

stone. Once 45% of the stone was di$placed effectively, the wall was 

considered to be totaled. Appendix A describes in detail the 

engineering analysis used to evaluate the failure. Costs associated 

with destruction of the seawall were based on repair costs at $36 per 

ton of rock plus contingencies (25%). engineering design (5%) and 

supervision of construction (5%). Volumes for the wall were calculated 

and to obtain the quantity of rock required,a void ratio of 37% was 

utilized, based on boring data obtained in connection with this 

investigation. A density of 179 lbs/cubic foot was used to obtain the 

required tonnage. 

D93. Damage to Roads and Infrastructures. Damage was calculated based 

on storm recession undermining the facility necessitating replacement 

and emergency bypassing. For utilities and roads perpendicular to the 

ocean front, damage was taken based on the linear feet of recession 

impacting the facility. For infrastructures paralleling the ocean, 

damage was considered when recession reached the utility. For roads 

paralleling the ocean front, damage was evaluated starting at the ocean 

side of the roadway and linearly evaluated to 100% damage at the 

landward side of the roadway. 

227 
N 

N 

00 

TABLE D - 16 

SEABRIGHT TO OCEAN TOWNSHIP 

RESIDUAL AVERAGE ANNUAL DAMAGE 

SUMMARY TABLE - 50 FOOT BERM - ALL PLANS 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

50 FOOT PROJECT 

DAMAGE TO BUILDINGS 

PHYSICAl 

EMERGENCY 

LOST INCOME 

BUILDING TOTAl (NO AffLUENCE) 

ADJUSTMENT fOR 

AFFLUENCE 

BUILDING TOTAL (WI AFFLUENCE) 

DAMAGE TO SEAWAlLS 

DAMAGE TO ROADS AND 

INfRASTRUCTURE 

PUBliC EMERGENCY COSTS 

1 2 

$666.5 52,170.5 

529.1 5126.2 

$6.0 525.4 

DAMAGE IN THOUSANDS OF DOLLARS 

3 4 

1673.2 11,021.9 

141.8 137.7 

510.9 18.0 

5 

1167.1 

18.0 

12.3 

6A 

$157.8 

14.6 

$0.9 

5701.612,322.2 1725.8 11,067.6 1177.4 1163.3 

124.9 143.3 148.9 114.7 17.7 13.1 

5726.6 52,365.4 5774.7 51,082.3 5185.0 5166.4 

5761.3 $0.0 5371.9 5190.9 5283.9 $0.0 

$0.0 $0.6 $0.2 $0.0 $0.0 575.7 

$1.4 $0.4 $0.3 $0.4 $0.7 $0.3 

. " 

--------------------------------------------------------------------------------------------.-----

TOTAL RESIDUAL DAMAGES 51,464.3 52,323.2 51,098.3 51,258.9 5461.9 5239.3 

(NO AfFLUENCE) 

TOTAl RESIDUAL DAMAGES 51,489.252,366.4 51,147.1 51,273.6 $469.6 5242.4 

(WI AFfLUENCE) 
N 

N 

\0 

TABLE D - 16 

SEABRIGHT TO OCEAN TOWNSHIP 

RESIDUAL AVERAGE ANNUAL DAMAGE 

SUHHARY TABLE - 50 FOOT BERM - ALL PLANS 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOHIC REACH 

50 FOOT PROJECT 

DAMAGE TO BUILDINGS 

PHYSICAL 

E"ERGENCY 

LOST INCOME 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUST"ENT FOR 

AFFLUENCE 

8A 

513.9 

50.2 50.1 

114.2 

50.4 

8B 

SO.1 

SO.O 

SO.O 

50.1 

SO.O 

DAMAGE IN THOUSANDS OF 

9A 

561.6 

$2.1 

SO.4 

564.0 

n.o 

9B 

524.8 

SO.8 SO.2 

525.8 

SO.3 

10 

521.0 

SO.5 

SO.1 

521.6 

SO.9 

-----------------------.---------.--------------------------------------------------------

BUILDING TOTAL (WI AFFLUENCE) 

DAMAGE TO SEAWALLS 

DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC E"ERGENCY COSTS 

TOTAL RESIDUAL PAMAGES 

(NO AFFLUENCE) 

TOTAL RESIDUAL DAMAGES 

(WI AFFWENCE) 

514.6 

SO.O 

52.8 

$0.0 

$17.0 

$17.4 

SO.1 567.0 

SO.O SO.O 

50.0 13.9 

SO.O SO.2 

SO.1 578.1 SO.1 sa1.1 

$26.0 522.4 

525.8 50.0 

0.0 7.2 

SO.1 50.2 

551.7 529.0 

$51.9 $29.9 
N 

w 

0 

TABLE D - 17 

SEABRIGHT TO OCEAN TOWNSHIP 

RESIDUAL AVERAGE ANNUAL DAMAGE 

SUMMARY TABLE - 100 FOOT BERM - ALL PLANS 

(JUNE 1988 PRICE LEVEL) 8 5/81 INTEREST RATE 

ECONOHIC REACH 

100 FOOT PROJECT 

DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOtIE 

1 2 

1436.2 $1,815.6 

$21.6 $89.1 

$4.5 $20.6 

DAMAGE IN THOUSANDS OF DOLLARS 

3 

$371.8 

$24.8 

$7.3 

4 

$870.8 

$29.7 

$6.9 

5 

$75.7 

$3.7 

$0.9 

6A 

$37.9 

$3.0 $0.9 

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTtlENT FOR 

AFFLUENCE 

BUILDING TOTAL (WI AffLUENCE) 

DAMAGE TO 

DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC COSTS 

$462.3 $1.925.4 $403.9 $907.4 

$14.5 $37.4 $36.9 $24.0 

$476.8 $1,962.7 S440.8 S93,.3 

$146.3 $0.0 S72.3 S48.9 

SO.O SO.1 SO.1 $0.0 

SO.9 SO.3 $0.2 SO.3 

$80.2 $4.1.8 

$3.5 $2.3 

$83.8 S44.1 

S56.5 SO.O 

$0.0 S1.2 

SO.3 $0.1 

TOTAL RESIDUAL DAMAGES 

(NO AffLUENCE) 

TOTAL RESIDUAL DAMAGES 

(WI AffLUENCE) 

S609.5 S1.92S.7 S476.4 S956.6 S137.0 

S624.0 $1,963.1 S513.3 S980.S S14O.6 

S43.1 S45.4 
N 

w 

..... 

TABlE D - 17 

SEABRIGHT TO OCEAN TOWNSHIP 

RESIDUAL AVERAGE ANNUAL DAMAGE 

SUMMARY TABLE - 100 fOOT BERM - ALL PLANS 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

100 fOOT PROJECT 

DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

BUILDING TOTAL (NO AfFLUENCE) 

ADJUSTMENT fOR 

AffWENCE 

8A 

13.4 

10.2 10.1 13.7 

SO.1 

88 

10.0 

10.0 

10.0 

10.0 

10.0 

DAMAGE IN THOUSANDS Of DOL

9A 

13.3 

10.1 

10.0 

13.4 

10.1 

9B 

10.5 

10.0 10.0 10.5 

10.0 

10 

121.0 

10.5 

SO.1 

11

121.6 11

10.9 

----------------------------------------------------------------------------------------------

BUILDING TOTAL (WI AffLUENCE) 

DAMAGE TO SEAWALLS DAftAGE TO ROADS AND 

INfRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

TOTAL RESIDUAL DAMAGES 

(NO AFFLUENCE) 

TOTAL RESIDUAL DAftAGES 

(WI AFFLUENCE) 

13.8 

10.0 

10.0 

10.0 

n.7 

13.8 

10.0 n.5 10.6 

10.0 10.0 19.5 10.0 10.4 0.0 

10.0 10.0 10.0 

10.0 $1.8 $10.0 

10.0 $4.0 110.1 

122.5 11

10.0 

3.6 1

10.2 

125.4 $1

126.3 11
N 

I"..) 

N 

TABLE D - 18 

SEABRIGHT TO OCEAN TOWNSHIP 

RESIDUAL AVERAGE ANNUAL DAMAGE 

SUHHARY TABLE • 150 FOOT BERM - ALL PLANS 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

150 fOOT PROJECT 

DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

BUILDING TOTAL (NO AffLUENCE) 

ADJUSTMENT· fOR 

AffLUENCE 

DAMAGE IN THOUSANDS Of DOLLAR

1 2 

5284.7 51,739.4 

517.0 581.9 

Sl.9 520.5 

3 

5229.5 

517.5 

56.7 

4 

5745.8 

522.8 

56.2 

$305.7 51,847.8 $253.6 5774.7 

$9.2 $36.5 513.1 $13.6 

5 

538.6 

52.4 

50.7 

541.7 

$2.1 

6

537.

Sl.O 

50.

541.

52.

BUILDI", TOTAL (WI ·AffLUENCE) 

DAMAGE TO SEAWALLS DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

TOTAL RESIDUAL DAMAGES 

(NO AffLUENCE) 

TOTAL RESIDUAL DAMAGES 

(III AFFLUENCE) 

5314.9 51,884.3 5267.3 5788.3 

$0.0 SO.O $0.0 $0.0 

SO.O SO.O 50.0 $0.0 

50.6 $0.3 50.1 SO.3 

5306.2 51,848.1 5253.8 $775.0 

5315.5 $1,884.6 5267.5 5188.6 

543.7 $43.

50.0 50.

50.0 SO.O 

50.2 50.

541.8 541.

$43.9 .543.
N 

w w 

TABLE D - 18 

SEABRIGHT TO OCEAN TOWNSHIP 

RESIDUAL·AVERAGE ANNUAL DAMAGE 

SUMMARY TABLE - 150 FOOT BERM - ALL PlANS 

(JUNE 1988 PRICE LEVEL) 8 5/8% INTEREST RATE 

ECONOMIC REACH 

150 FOOT p,ROJECT 

DAMAGE TO BUILDINGS 

PHYSICAL 

EMERGENCY 

LOST INCOME 

8A 

$3.3 

$0.2 $0.1 

8B 

$0.0 

$0.0 $0.0 

DAMAGE IN THOUSANDS OF OO

9A 

$0.8 

$0.0 $0.0 

9B 

$0.0 

$0.0 $0.0 

10 

$21.0 

$0.5 

$0.1 

$

BUILDING TOTAL (NO AFFLUENCE) 

ADJUSTMENT FOR 

AFFLUENCE 

$3.5 $0.1 

$0.0 $0.8 $0.0 $0.0 

$0.0 $21.6 $$0.0 $0.9 

---------------------------------------------.-----------------------------------------------

BUILDING TOTAL (UI AFFLUENCE) 

DAMAGE TO SEAWALLS DAMAGE TO ROADS AND 

INFRASTRUCTURE 

PUBLIC EMERGENCY COSTS 

TOTAL RESIDUAL DAMAGES 

(NO AFFLUENCE) 

TOTAL RESIDUAL DAMAGES 

(WI AffLUENCE) 

$3.7 

$0.0 $0.0 $0.0 

$3.5 

53.7 

$0.0 $0.8 

$0.0 $0.0 $0.0 $0.0 

$0.0 $0.0 

$0.0 $0.8 

$0.0 $0.8 

$0.0 $22.4 $

$0.0 $0.0 

0.0 0.3 

$0.0 $0.2 

$0.0 $22.2 $

$0.0 $23.0 $
TABLE D-19 

SUMMARY OF AFFLUENCE CALCULATIONS 

What is the Income Growth Rate Type? 2 • Projected Incomes 

How many years to the base year? 5 

Input personal income projections at ptesent, at base year, and 

subsequent 10-year intervals up to Base Year + 50. There should be 

seven figures, each separated by a comma. 

6880,7663,8662,9432,10183,11020,11926 

Subperiod Growth Rates are: 

What % of 

2.18 

1. 25 

0.86 

0.77 

0.79 

0.79 

residential value 

Years After Base 

0 

10 

20 

30 

40 

50 

is contents? 

Base Factor 

1.114 

1.259 

1. 371 

1.480 

1.602 

1. 733 

Growth assumed to end after 50 years. 

234 

% 

28% 

Contents 

31.2 

35.3 

38.4 

41.4 

44.6 

48.5 
Public Emergency Costs 

094. The costs of additional public services during storm events were 

analyzed using data provided by the municipalities for various storms. 

The towns of Deal and Loch Arbour did not report any historic costs. In 

order to estimate the emergency costs, it was assumed that costs would 

vary in relationship to damages to buildings. Data provided by Monmouth 

Beach indicated higher damages during the March 1984 Storm than for 

other storms of greater intensity. This inconsistency was apparently 

caused by the failure of a portion of the seawall leading to additional 

evacuation and public housing costs. Damage frequency curves were 

developed for each community. Because no recorded historic data was 

available for a major flood event, the curves were extrapolated using 

the general shape of the damage frequency curves for buildings in 

combination with historic data for the March 1984 Northeaster and 

Hurricane Gloria, September 1985. 

095. Residual emergency costs were calculated based on the ratio of 

residual damage to buildings vs. the without project damage to buildings. 

Seawall Maintenance Costs 

D96. Maintenance costs upon implementation of the various alternatives 

are reported as a portion of the annual project costs. Costs presently 

being expended by the State to maintain the existing seawall therefore 

become a project benefit. Historic data on maintenance costs were 

supplied by the State of New Jersey Department of Environmental 

Protection, Division of Coastal Resources for a period of record from 

1963 to 1983 for the towns of Sea Bright and Monmouth Beach. The data 

was updated to June 1988 price levels using the consumer price index and 

then averaged over the reporting record. For Sea Bright the total 

expenditure for the 20-year period was $7,780,000 adjusted to June 1988 

price levels, which yields an annual maintenance cost of $389,000. 

Based on a total of 20,495 linear feet, the average annual maintenance 

cost per linear foot of seawall in Sea Bright is estimated to be $18.98. 

In Monmouth Beach the 9455 lineal feet of seawall has received 

$1,023,000 in 1988 dollars for maintenance over the 20 year period of 

record, yielding an average annual maintenance cost of $5.41 per linear 

foot. 

D97. South of Monmouth Beach there is a seawall at Long Branch and 

Deal. Unlike the Sea Bright and Monmouth Beach seawall both of these 

structures are backed by a bluff and no data was available on historical 

maintenance. For the purpose of benefit analysis, it was therefore 

assumed that no maintenance is presently performed south of Nonmouth 

Beach. 

098. Within the two towns where maintenance is being performed, which 

encompasses rea"ches 1-5, the cost per lineal foot of seawall was 

utilized in conjunction with the footage of seawall to evaluate the per 

reach benefit. Tables D-13 through D-15 show the results of the calculation. 

235 
ERODED LAND VALUES 

099. Under the without project scenario the project area is subject to 

a loss of land due to long-term erosion. The value of this land represents a potential project benefit as long term erosion will be halted by 

the project nourishment program. The nourishment program will prevent 

future losses of property to long term erosion resulting in a project 

benefit.. To qu~tify land loss damages the acreage subject to erosion 

was identified. This was accomplished by initially obtaining the ocean 

frontage for each reach and then applying the long-term historic erosion 

rate of 3 feet per year. As described earlier in the appendix, longterm erosion was assumed to be halted at the leading edge of seawalls 

and road system paralleling the beach, based on anticipated intervention 

by man. Review of shoreline development and erosion protection 

structures indicated that actual loss of developed land is limited to 

economic reaches 8A, 9A and 11. Land loss in other reaches consist 

primarily of beach area and recreation lands. For each town existing 

land values, as indicated in Table 0-20, were established by gross value 

estimates and then applied to the potential acreage lost per year for 

the fifty year project life. These values are representative of 

nearshore land. A present worth analysis was then performed on the 

results. The sum of the present worth figures was amortized over the 

life of the project using an interest rate of 8-5/8%, yielding an 

average overall damage for eroded land. A detailed description of the 

procedures utilized in establishing the real estate appraisal is 

contained in Sub-Appendix D-l "Land Appraisal Attachment". Since under 

with project conditions long-term erosion will be halted by annual 

nourishment this figure represents the average annual benefit associated 

with lost land. Table 0-21 is a sample calculation of the analysis. 

D99A. As previously noted a significant portion of the without project 

erosion would consist of beach area and recreation lands. This area 

includes four significant public recreation areas; Sea Bright public 

beach; Monmouth public beach; Seven Presidents County Park; and the Long 

Branch public beaches. The recreation output of these beaches is 

anticipated to decline as long term erosion eliminates the existing dry 

beach area. Current recreation output of these areas, summarized in 

Table D21A, was determined using the without project willingness to pay 

(WTP) as described under recreation benefits in conjunction with 1985 

attendance using the following formula: 

Existing Value 

of Beaen = 

# of passes Sold at 

Beach 

Total Passes 

+ in Survey Area 

* Existing Value for Survey Area 

The value of lost recreation land was calculated in each year of the 

project life based on the percentage of usable area eroded. A present 

worth analysis was then performed on the results and the sum of the 

present worth figures was amortized over the project life resulting in 

annual benefits of $881,0'00. 

REDUCED MAINTENANCE AT SANDY HOOK 

0100. Iujmediately to the north of the project limit in the Sandy Hook 

unit of the Gateway Na~ional Park is a severe erosion area subject to 

washovers and breaching,. Based on the existing conditions sediment 

236 

(Rev. Harch 1990) 
budget aQalysis. the littoral drift deficit at the Sandy Book critical 

zone is approximately 101.000 cubic yards annually. Construction of a 

beach fill only project at Sea Bright to. Ocean Township vill eliminate 

this deficit. This vill res~lt in a fill maintenance reduction cost to 

the National Park Service which has initiated a beach restoration 

program to protect the only access road and recreation support 

facilities. 

DI01. Construction of a maintenance project would be accomplished by a 

27-inch pipeline dredge. The .borrov area offshore of the critical zone 

would be utilized with an overfill factor of 1.06. The maintenance 

cycle would be six year.. The attnual cost (benefit) vouldbe $1.702.133 

annually. Table D-22 details this calculation. 

D102. Fill Only Plan. Construction of a fill only erosion control plan 

from Sea Bright to Ocean Township will eliminate the littoral drift 

deficit and resulting erosion problem at Sandy Book. Accordingly. the 

entire $1.702.133 would be • project benefit. This benefit is 

independent of berm width. 

237 

(Rev. Karch 1990) 
...... 

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00 

TABLE D-20 

Sea Bright to Ocean Township 

Value of Eroded Land Under Existing and Without Project Conditions 

Price Gross Price 

per Land per 

Lineal lineal Value lineal 

Location Feet foot Estimate foot 

Loch Arbour 1,075 @ $5,000 $5,375,000 $5,000 / 

Deal 8,614 @ $5,000 - $43,070,000 $5,000 / 

Long Branch 22,268 @ $4,500 $100,206,000 $4,500 / 
SEABRIGHT TO OCEAN TWP. TABLE 0-21 CALCULATIONSOF AVERAGE 

EROSION BENEFITS CALC SHEET ANNUAL BENEFITS FOR LOST LAND 

REACH 9A JUNE 1988 PRICE LEVEL 

RATE 8.625% PROJECT LIFE 50 YEARS 

DATE PROJECT LAND LOST LAND VALUE VALUE IN PWF PRESENT CRF 50 AAD 

YEAR YEAR L.F. 5/SF YEAR WORTH I NCRE"E

---------- ------- ----------- - ----------. ----------- ------- ------------- - ------- -----------

1985 520 0 50 0.08765 

1986 1330 520 579,800 50 0.08765 

1987 2660 520 5159,600 50 0.08765 1988 3990 520 5239,400 50 0.08765 

1989 5320 520 5319,200 50 0.08765 

1990 6650 520 5399,000 50 0.08765 

1991 1 6601 520 5396,060 0.9206 5364,612 0.08765 531,95

1992 2 6552 520 5393,120 0.8475 5333,170 0.08765 529,20

1993 3 6503 520 5390,180 0.7802 5304,422 0.08765 526,68

1994 4 6454 520 5387,240 0.7183 5278,138 0.08765 524,371995 5 6405 $20 5384,300 0.6612 5254,110 0.08765 522,27

1996 6 6356 520 5381,360 0.6087 5232,143 0.08765 520,34

1997 7 6307 520 5378,420 0.5604 5212,063 0.08765 518,58

N 1998 8 6258 520 $375,480 0.5159 5193,708 0.08765 516,97

w 1999 9 6209 520 5372,540 0.4749 5176,931 0.08765 $15,50

\0 200D 10 6160 520 $369,600 0.4372 5161,597 0.08765 514,164 

2001 11 6092 520 5365,520 0.4025 $147,124 0.08765 512,895 2002 12 6024 520 5361,440 0.3705 5133,930 0.08765 511,73

2003 13 5956 520 ,357,360 0.3411 5121,904 0.08765 510,685 

2OD4 14 5888 520 5353,280 0.3140 5110,944 0.08765 59,724 

2005 15 5820 520 $349,200 0.2891 5100,955 0.08765 $8,849 

2OD6 16 5752 520 5345,120 0.2661 591,853 0.08765 58,051 

2007 17 5684 $20 5341,040 0.2450 583,560 0.08765 57,324 

2008 18 5616 520 '336,960 0.2256 '76,005 0.08765 $6,662 

2009 19 5548 520 5332,880 0.2077 '69,123 0.08765 56,059 

2010 20 5480 520 '328,800 0.1912 562,854 0.08765 55,50

2011 21 5479 520 5328,740 0.1760 557,853 0.08765 55,071 

'"' 2012 22 5478 520 5328,680 0.1620 553,250 0.08765 '4,667 l::d 

II) 2013 23 5477 520 1328,620 0.1491 549,013 0.08765 54,29

< 2014 24 5476 520 5328,560 0.1373 $45,113 0.08765 53,954 . 2015 25 5475 520 5328,500 0.1264 $41,523 0.08765 13,64

2016 26 5474 '20 1328,440 0.1164 $38,219 0.08765 13,35

11 2017 27 5473 520 5328,380 0.1071 535,178 0.08765 $3,083 

n 2018 28 5472 520 '328,320 0.0986 532,379 0.08765 52,83

::T 2019 29 5471 '20 5328,260 0.0908 529,803 0.08765 52,612 ..... 

\() \() 

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OATEPROJECT 

YEAR YEAR 

SEAllt IGHT 10 OCEAN TIIP. 

EROSION BENEfiTS CALC SHEET 

REACH 9A 

RATE a.6251 

LAND l.OST LAND VALUE 

L.F. I/Sf 

VAlUE IN 

YEAR 

TAllE 0-21 CALCULATIONSOf AVERAGE 

ANNUAL BENEf ITS FOR LOST lAND 

JUNE 1988 PRICE LEVEL 

PROJECT LIFE 50 YEARS 

PVF PRESENT CRF 50 

WORTH 

AAD 

INCRE"ENT 

---------- ------- ----_ .. _--- - ----------- ----------.-- - ------. -----------.- --

2020 lO 5470 120 IJ2a,2OO 0.0836 127,431 0.08765 12,404 

2021 31 5444 120 '326,640 0.0769 125,133 0.08765 12,203 

2022 32 541a 120 IS25,08O 0.0708 123,027 0.08765 12,01a 2023 33 5392 120 1323,520 0.0652 '21,097 0.08165 11.a49 

2024 34 5366 120 1321,960 0.0600 119,328 0.08765 11.694 

2025 35 5340 120 1320,400 0.0553 117,707 0.08765 11.552 

2026 36 5314 120 131a,140 0.0509 1,6,222 0.08765 11,422 

2021 ]7 5211 120 1317,280 0.0468 114,861 0.08765 11,303 

202a 31 5262 120 1315,720 0.0431 113,614 0.08765 11,193 

2029 39 5236 120 1314,160 0.0397 112,471 0.08765 11,093 

2030 40 .5210 120 1312,600 0.0365 111,423 0.08765 11,001 2031 41 5192 120 1311,520 0.0336 110,480 0.08765 1919 2032 42 5114 120. 1310.440 0.0310 19,614 0.08765 $843 

2033 U 5156 120 1309,360 0.0285 18,820 0.08765 un 

2034 44 5131 120 1308,280 0.0262 18,092 0.08765 1109 2035 45 5120 120 1307,200 0.0242 17,423 0.08765 1651 

2036 46 5102 120 1306,120 0.0222 16,810 0.08765 1597 

2037 41 5084 120 1305,040 0.0205 16,241 0.08765 1548 2031 41 5066 120 1303,960 0.0189 15,730 0.08765 1502 2039 49 5048 120 1302,880 0.0174 15,257 0.08765 1461 2040 50 5030 120 1301,800 0.0160 14,822 0.08765 1423 

LONG TER" 

AAD • 136
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Location 

Sea Bright 

Honmouth Beach 

Seven Presidents 

County Park 

Long Branch 

Totals for 

Area 

Totals for 

Survey Area 

'l'ABLE D-21A 

Bxisting Recreation Output 

Project Area Public Beaches 

(June 1988 Price Level) 

DallyPa8ses Season 

I Value I 

29,000 $120,945 461 21,000 $87,955 887 

124,000 $517,550 2,828 

90.002 S37!t.9Z2 1. 750· 

264,000 $1,101,420 5,926 

2,220,000 $9,258,540 48,491 
(Al 

FILL 

VOLUME 

YEAR (C.Y. ) 

TABLE D-22 

June 1988 Price Level 

Project Life 50 Years 

SARDY lOOK OUTICAL ZONE 

HAINT!lWICE REDUCTIOlf BENEFIT 

FILL ONLY PLAN 1"8-5/8 % INTEREST 

(B) (C) (D) (E) 

FILL !t:lB &. FILL TOTAL 

UNIT D!HJB FUTURE FUTURE 

COST COST WORT! WORT! 

(S) (S) ($) (S) 

(F) (G) 

PRESENT PRESENT 

WORT! WORT! 

FACTOR (S) 

---------------------------------------------------------------------.------------------

1990 710,838 7.31 1,000,000 8,287,452 8,287,452 1.00000 8,287,452 

1996 710,838 7.31 1,000,000 7,292,958 7,292,958 0.60873 4,439,407 

2002 710,838 7.31 1,000,000 7,292,958 7,292,958 0.37055 2,702,379 

2008 710,838 7.31 1,000,000 7,292,958 7,292,958 0.22556 1,645,006 

2014 710,838 7.31 1,000,000 7,292,958 7,292,958 0.13730 1,001,357 

2020 710,838 7.31 1,000,000 7,292,958 7,292,958 0.08358 609,SSl 

2026 710,838 7.31 1,000,000 7'292,958 7,292,958 0.05088 371,049 

2032 710,838 7.31 1,000,000 7,292,958 7,292,958 0.03097 225,867 

2038 710,838 7.31 1,000,000 7,292,958 7,292,958 0.01885 137,491 

-----------------------------------.----------------------------------------------_ .. _-----------

TOTAL 819,419,558 

CAPITAL llECOVEllY FACTOR 0.08165 

TOTAL INITIAL FILL VOLUME (C.Y.) 710,838 

ANNUAL COST 

TOTAL FIllST COST or FILL 

ANNUAL FILL COST 81,102,000 

TOTAL ANNUAL BENEFIT $1,702,000 

NOt!: 0-( (.AXII)+C)X (1 +CONTINGENCY)X ( 1 +ENGIlIEElING&I)ESIGN( % )+SUPEllVISION8oINSP!CTION (% ) ) 

25 % CONTIlIGDCY FOIl INITIAL PRO.7ECTS 

10 % CONTING!NCY FOIl MAINTENANCE PllOJECTS 

3.0 % E6D 4.0 % S&A 

CAPITAL RECOVERY FACtoR -

242 

81,102,133 
0103. Authorized Groin Plan. Construction of the authorized groins is 

expected to reduce the loss of fill within the groin field by 15%. This 

would decrease the fill maintenance benefit at Sandy Hook. The annual 

benefit for this plan would be $1,489,678. These benefits are also 

independent of berm width. 

0104. Updated Groin Plan. The updated groin plan was designed to 

reduce the littoral drift potential at the nor.th end of the project to 

the existing rate of sediment movement. No significant reduction of 

erosion is anticipated for this erosion control plan. 

INTENSIFICATION BENEFITS 

0105. The plans of improvement will create intensification benefits. 

Intensification benefit is defined in ER1105-2-40, Section IV, pages 

2.4.2(b) (2) as follows: 

"(2) Intensification benefit. If the type of floodplain use is 

unchanged but the method of operation is modified because of the plan, 

the benefit is the increased net income generated by the floodplain 

activity." . 

Paragraph 2.4.13(b) of the same document contains instruction on 

calculating intensification benefits as follows: 

"(b) Land use is same but more intense with project. If land use is 

the same but more intense, as when an activity's use of the floodplain 

is modified as a result of the project, base determination of the 

increase in income on increased land values." 

0106. Sub-Appendix 0-1 "Land Appraisal Attachment" details the 

appraisal methodology utilized in determining the intensification 

benefit for the overall project. The added values of land resulting 

from the project is $92,650,000 which has been annualized over the 

SO-year project life to provide a· net benefit of $8,121,000. 

0107. This increased land value is driven by the storm protection 

erosion control accomplishments of the project. A local example of this 

process is the area near 7 Presidents Park in North Long Branch where a 

minimal protective beach has been maintained. Development has intensified from primarily older single and multi-family rental hOUSing towards 

high quality townhouses and condominiums. 

243 
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W/PROJECT FUTURE CONDITIONS 4. RESIDUAL STORM DAMAGE TO IMPROVEMENTS 

EXISTING CONDITIONS 3. STORM DAMAGE TO IMPROVEMENTS 

I. ADDED BEACH AREA. 

VALUE OF INCREASED 

RECREATION CLAIMED. 

2. EXISTING LAND AREA 

WITHIN 250' OF 

H.W.L. NET INCREASE 

IN LAND VALUE 

CLAIMED AS INTENSifiCATION. 

3. STORM DAMAGE 

(BUILDINGS. ROA

AT EXISTING CO

4. STORM DAMAGE 

W IPROJECT FUT

RESIDUAL DAMA

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" 

" ------ 

I. LAND ERODED • 3fT 1 YR. 

(HAL TED • MAJOR ROAm 

EXISTING VALUE Of LAND 

ERODED 1991-2040 CLAIMED. 

2. STORM DAMAGE TO IMPROVEMENTS 

(BUILDINGS. ROADS AND UTiLlTlESt 

AT EXISTING CONDITIONS. 

.3. STORM DAMAGE TO IMPROVEMENTS 

W 10 PROJECT fUTURE CONDITIONS. WITHOUT PROJECT DAMAGES CALCULATED 

AS EOUIV_LENT ANNUAL DAMAGE 

1991-2040. 

------------ 

------
, 

MONMOUTH· 

COUNTY . 

•. . ". 

........• :: 

.. " . . .. 

sc.al.~ IN IlILES 

o 2 4 a ' 

SANDY HOOK GATEWAY 

NATIONAl. RECR.EATION AREA 

~AOOITIONAL BENEFIT AREA 

r-___ NORTHERN STUDY 

AREA LIMIT 

SEA BRIGHT 

MONMOUTH lEACH 

LONG BRANCH 

ev~~~~~T~w~H~5~H'~p __ SOUTHERN STUDY 

AREA LIMIT 

BRADLEY BEACH 

·'0 -- . • __ AVOH-8Y-THE SEA 

LAICE 

IIANASQUAN 

LOCATION OF STUDY AREA 

246 FIGURE D3 
"II 

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I. STRUCTURE I ... 

INVENTORY 

COMBINED DAMAGE CALCULATION 

FLOW NET 

2. DEPTH 

DAMAGE 

FUNCTIONS 

3. INUNDATION 

.. I DAMAGE 

fREQUENCY 

_ 

.. 

II. ADJUST I I REPEAT STEP

SHORELINE 3 THROUGH .. 

FOR LONG TERM .. FOR YEARS 

EROSION 

.. 

N 

10. DAMAGE MAX. DAMAGE" DAMAGE " 7. EXISTENCE 9. ADJUST H8. MAXIMUM 

fREQUENCY FOR EXISTENCE AT EACH PROBABILITY 

IN YEAR H PROBABILITY STORN FREGUENCyH (FUTURE YR5.1 

12. EQUIVALENT 

• ... I ANNUAL 

DAMAGE 
I 

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ECONOM IC REACH IOUNDRIES 

249 

FIGURE 01 
SHREWSBURY RIVER 

FLOOD STAGE ,,--,;::.. 

WAVE BREAKING 

OVER WALL\ 

SCHEMATIC OF FLOODING 

BEHIND SEA WALL 

OCEAN 

STORM 

SURGE 

FIGURE 0-7 

250 
$ 

DAMAGE 

f 

o 

HOUSE 'A' 

r-------------

WAVE _--1...,1 

ATTACK i 

I STORM ! pRECESSION 

I r-" . ---- I / 

CRITICALAI 

DAMAGE /1 

/1 I 

I 

I 

I 

. I 

INUNDATION 

~--~------------------~------------------------ EVERY YEAR ... 

FREQUENCY 

SCHEMATIC OF CRITICAL 

DAMAGE ANALYSIS 

VERY INFREQUENT 

FIGURE o-a 

251 
APPENDIX C 

AN EXAMPLE OF SHORELIlm DAMAGE ASSESSMENT 

253 
254 
lJS Army Corps 

of Engineers 

_os Angeles District 

SANTA BARBARA COUNTY 

BEACH EROSION AND STORM DAMAGE REDUCTION 

RECONNAISSANCE STUDY 

AMENDED FINAL REPORT 

FEBRUARY 1990 

255 
256 
APPENDIX A 

COASTAL PROCESSES 

Part II 

Methodology for Shoreline Damage Assessment 

1. Introduction 

The primary objective of this analysis is to predict the maximum 

landward extent of damage to shorefront properties by storms during extreme 

events for three assigned locations within Santa Barbara County: East 

Beach, Miramar Beach, and Carpinteria Beach. Storms under consideration 

for this analysis, called "design storms", are characterized by their 

return (or recurrence) intervals: 15, 2S, SO, and 100 years. 

One of the most important factors affecting the extent of wave front 

encroachment on shorefront property is the sea level. Various processes 

contribute to raising the sea level during the storm, among them the global 

climatic fluctuations (such as ENSO: E1 Nino Southern Oscillation), storm 

surges associated with barometric pressures, wind setup. wave setup and 

surf beat, and the astronomical tide. The previous FEMA study evaluating 

100-year coastal flooding potentials took into consideration only some of 

these processes (Lee et al., 1982). In particular, the FEMA study ignored 

the global climatic fluctuations and further considered wind setup as insignificant in southern California. However, these factors proved to be of 

critical importance in the disastrous 1982-83 winter storms which occurred 

immediately after the FEMA methodology had been established. 

In this assessment of wave front encroachment, the global climatic 

fluctuations and wind setup are taken into consideration. Additionally, 

this assessment incorporates the effect of shoreline retreat in the evaluation of horizontal excursion of the wave front - a feature which was also 

missing in the FEMA study. Other additional factors incorporated in this 

assessment are: storm duration, wave direction, and shore topography. 

Following are two sections: the first presents a summary of the computational methodology employed to derive the landward extent of shoreline 

damage, and the second presents details regarding the available sources of 

data needed for input to the methodology, and the characteristics of the 

data selected for use. 

2. Summary of Computational Methodology 

Figure A-1 shows the flow diagram of the computations in which the 

wave front encroachment on the shorefront properties are computed as a 

function of the frequency of occurrence of design storms. The end products 

of these computations are the horizontal and vertical positions of the maximum wave front encroachment occurring during the design storm. 

257 
r 

FIGURE A-1: 

FLOW DIAGRAM FOR SHORELINE DAMAGE 

ASSESSMENT COMPUTATIONS 

1 

*EX1'RCVE EVENTS i 

PR:BAB I LIlY I 

I 

1" I I 

*S"Tt:RA *WA.VEI CCEAN WA.VE WA.TER l..EVEL 

C!.R'\TI~ DIRECTI~ I (1) Ho 

(6) 

LOCAL DEEPWATER WA.VE 

(2) HI 0 

J, 

BREAKIf\C ." WA.VE 

(3) rs 

,II , V \It ~ SKR: ER)51~ SI-mE R.,N-UP 

I+-

("i) 

lOR:X:RAA-IY ... 

~X ,. RH , RV 

(4) 

H:RIZCM"AL VERTICAL 

WA.VE FKNT WA.VE FR:NT ... 

~ EXQ.RSI~ ~ 4 EXQ.RSI~ 

~ = ~ + ~x + € Wv=Y+Ry 

NOTE: 

(1) VES SEAS (Sea-State Engineering Analysis System) hindcast data between 

1956-1975 at 34.22 N (lat.) and 121.48 V (long.). 

(2) Regression between the simultaneous hindcast data in the ocean and within 

Santa Barbara Channel since 1973, by Pacific Veather Analysis (1987). 

(3) .National Harine Consultants (1960) refraction study: "Oceanographic Study _ Santa Barbara, California, 92 NHC-CE (60)". 

(4) Holman, R.A., 1986: "Extreme Value Statistics tor Vave Run-Up on a Natural . Beach", Coastal En,., 9 (1986), 527-544. . . (5) Kriebel, D.L. (198 ): "Beach and Dune Response to Hurricanes", H.S. Thesis, 

Univ. of Florida, Gainesville, FL, 313 p. & Appendix. 

(6) Chiu, T. Y. and R. G. Dean, 1954: "Hl!thodology on Coastal COnstruction 

Control Line Study", Department of Natural Resources, Division of Beaches 

and Shores, State of Florida, 169 p. 

(7) NOAA Tide Gage Data at Santa Honica Pier, 1933-82. 

(*) Simulated by rando. numbers. 

258 

Y 

~ 
The horizontal excursion, expressed WH, is a sum of horizontal wave 

runup shoreward of the existing water level R

H, the net shoreline recession 

caused by the storm 6X, and all other effects affecting the shoreline position, expressed as t, including specifically the seasonal setback of the 

shoreline and the cumulative recession due to a continuous long-term recessi?n (assume.d in this a~a~ysis t.o be 0 ft/yr, C'lwa will be deter- rn~ned dur1ng the feas~b1lity study. 

6 X + t (1) 

Note that the horizontal wave runup RH is referenced to the water level 

occurring at the time of the storm, thus including the effect of storm 

surge if there is one. The vertical wave front excursion Wv is a sum of 

the water level at the time of the storm Y and the vertical wave runup RV' 

Y + (2) 

A special effort was made to perform these computations with minimum 

of hypotheses. To simulate the statistics of ocean waves, a recent 20-year 

ocean wave hindcast study by Wa~erways Experiment Station was employed, 

using data for a location 34.22N (lat.) a~d 121.48V (long.), called SEAS 

(Sea-State Engineering Analysis System) Station No.9, about 100 miles 

southwest of Point Conception. Although this data set does not include 

swell from the southern hemisphere, this deficiency is not critical to this 

study since it focuses on extreme wave events. Comparison of the SEAS data 

with other statistics available in this region shall be discussed in detail 

in the following section. 

The procedure for deriving nearshore wave heights involves selecting 

design (deep-water) waves in the Pacific Ocean as given by the SEAS 

hindcast data and then propagating these waves to the project sites in two 

steps: first to deep-water locations in Santa Barbara Channel and then as 

far as the breaker line. The first step of this propagation process, i.e. 

from the Pacific Ocean into Santa Barbara Channel, is handled by comparing 

the simultaneous wave data for these two locations during major storms computed by Pacific Weather Analysis (1987) since 1973. In the second step, 

the deep-water waves in Santa Barbara Channel thus derived are refracted to 

the breaker line using the refraction/shoaling coefficients which have been 

generated in a prior study by the National Marine Consultants (1960). In 

the NMC study (1960), wave refraction/shoaling coefficients are available 

for three incident wave directions: 135 degrees, 255 degrees. and 270 degrees, at each of the project sites: East Beach, Miramar Beach, and 

Carpinteria Beach. 

The computation of wave runup employs input hom the breaking' wave 

heights thus derived and the knowledge of shore topography. This computation is performed using Holman's (1986) study on wave runup on a natural 

beach which is based on extensive and reliable field data. Since th~ 

landward excursion of the wave front depends upon the horizontal erosion of 

the shoreline during the storm as well as the horizontal 

259 
component of the wave run-up, shoreline erosion due to the storm must be d~termined in order to establish complete information of wave runup on the 

shore topography. 

computation of shoreline erosion requires input describing breaking 

wave heights, shore topography, and storm duration. This computation is 

performed using a numerical model developed by Kriebel (1982). The Kriebel 

model received a high rating as the best overall model of its kind in a 

recent review by CERC (Birkemeier et al., 1987). This model was also extensively calibrated against field data and utilized for the determination of 

setback lines by the State of Florida (Chiu and Dean, 1984). The water 

level during a design storm, which must be input into the Kriebel model, is 

based on the measured historical maximum annual water levels at the NOAA 

tide station at Santa Monica Pier between 1933 and 1982. This station has 

the longest tide measurements in the general vicinity, and the daia from 

this station offers the best available approximation to the project sites 

since the elevations of tidal planes at this station are essentially 

similar to those at Santa Barbara. 

Since it would be costly to carry out a simulation for the full range 

of variable beach topography, computations of both wave runup and shoreline 

erosion assume a single standard shore topography in which the beach face 

slope is IV:I0H, with a uniform berm height of 10 ft. This approach makes 

it possible to utilize the results of computations on shore erosion which 

have been already completed by Kriebel (1982). This hypothetical topography fits relatively well with typical beach profiles at East Beach. 

Since the shore topography at Miramar Beach and Carpinteria Beach departs 

from this standard condition, the local topography is taken into consideration when applying the results of damage assessment methodology to these 

sites. 

There are three variables in the overall flow of computations which 

are probabilistic in nature. These are: extreme water levels, storm wave 

directions, and storm durations. In order to simulate the probabilistic 

nature of these variables, a random number scheme is employed in this 

study. The flow chart of this procedure is shown in Figure A-2. The method 

is essentially one of Monte Carlo simulation, in which a random number is 

generated to represent the combination of the extreme water level probability, storm duration, and wave direction for the design storm for each year. 

In this procedure, the first three digits of the random number were taken 

to express the exceedance probability of the year's maximum water level. 

The two ensuing digits represented the wave direction, and the last two the 

storm duration. 

Damag~ assessment computations.wer& performed only for extraordinary 

events as defined by the first three digits of the random numbers, namely 

the events with return intervals exceeding 15 years. For instance, if the 

first three digits of a random number. were, say, ~25, this meant that the 

maximum water level for this year had an exceedance probability of 0.025, 

corresponding to a return period of 40 years (= 1/0.025).' Since this represents an extraordinary event, the subsequent steps of computation aiming at 

maximum storm wave front excursion were performed. If the three digits of 

the random number were instead 572, the maximum water level for this year 

represented a return period of only 1/0.572 1.75 years, a minor 

260 
NO 

FIRST 3 DIGITS 

WATER lEVEL 

(N) 

N < 0.077 

YES 

EXECUTE 

W AVE FRONT EXCURSION 

PREDICTION 

(SEE AC. A-1) 

7-DIGIT 

RANDOM NUMBER 

2 DIGITS FOR 

W AVE DIRECTION 

2 DIGITS FOR 

STORM DURATION 

I 

FIGURE A-2: flOW DIAGRAM FOR MONTE CARLO PROCEDURES TAKING INTO 

ACCOUNT PROBABILISTIC VARIATIONS OF WATER lEVel, WAVE 

DIRECTION, AND STORM DURATION 

261 
storm, and the subsequent computations to derive ~ave front encroachment on 

the shorefront properties ~ete abandoned. 

The next t~o digits of the random number ~ere considered to represent ~ave directions, 01 through 33 for SE, 34 through 66 for SY, and 67 through 

00 for Y. The last two digits were used to designate storm duration. Namely 

if these digits were 45, it meant that the storm continued for 45% of the 

time required to fulfill 99% of the steady state erosion. 

These Monte Carlo procedures ~ere repeated 100 times to simulate a 

history of extraordinary events for a continuous string of 100 years. Since 

the scenario of extraordinary events for any given 100-year duration ~ill 

be probabilistic, a lOO-year simulation ~as repeated a total of 10 times to 

take into account a range of variabilities of the 100-year history, resulting in a total simulation period of 1000 years. 

It is important to recognize that the ~ave front encroachment distances predicted by the procedures described above define the extreme tip 

of the wave s~ash. Since the ~ater at this point is too shallow to cause 

damage, an adjustment must be made to define encroachment values ~hich 

could cause damages to .the shorefront properties. The method for this adjustment is based· oil the assumption that the swash motion follo~s a 

Rayleigh distribution, and that the critical ~ave front value can be 

defined as representing an average of the one tenth highest run-up (about 

76% of maximum run-up) values. From the point of vie~ of damage assessment, 

the critical values of encroachment are deemed as being the farthest 

landward extent of total damage caused by a particular storm event. 

The final products of the computational procedures presented above 

are summarized in Figures A-3 and A-4, ~hich sho~ the data points of the 

horizontal and vertical critical ~ave front encroachment distances versus 

their corresponding probability of occurrence for East Beach, Miramar 

Beach, and Carpinteria Beach. In order to identify the most conservative 

prediction of critical wave front encroachment, the boundary for the maximum values for different return interval storms ~as selected and is shown 

by the straight-line approximation in these figures. Table A-I summarizes 

the predicted critical values for the various design storms at the respective study sites. Recalling that the methodology assumes a simplified 

beach topography in order to facilitate the computations, the application 

of these predicted values to the individual study sites must take into consideration the actual local topography. 

262 
.1..0 . . r----~I-·~--· --'-~---" --

.. ! 

I • 

I . '--'- - . . -. . ---.. -_ .... I 

• I .~--f---;-'--"----' -----.. -+ .----. /1:10 

100 

I------+--.--r-.~ ".-... -... --·-i!---- -.-- _._--

t---'-.~ ~ '. J-L-.----- . MIRAMAR BEACH 

·1'·:···· i . i 

,. f) 6 

>- !::: 

......I 

25 ". {)~ « . co 

0 

~ 

a.. P.D" 

I.U 

U 

'Z '. 

« 

0 ()" I.U 100 

I.U 

U 

X 

I.U ~oB 

. I·. r-• ~ 

\. • i 

t--"----+--. -. -+ .. j?~-_~-___ !_-~ I ~ _. __ 

• •• •• 1 • I 

.: • I '-

:--~ ---.• --.. 0" --r . ---- -~'" ------ t--~-__i-.--. ..... -.------C:-----···- .. '\. 

--T-, -~ - ~T- ___ T_f) __ _ 

I-----+-' -- - f'" I - : ---.. --- • e. ••• • I. : 

--.- ,~---;- .. --t----,- " -- CARPfNTER~ BEACH 

. I 

" 

.1..0 

.1..0 

~ I 

1------+----+---'- L 

I-----+---:-----j-~--- .--l; . " .~---.---

1------1----_.-'-- .'-7---=------

100 

HORIZONTAL WAVE FRONT ENCROACHMENT (FT) 

FIGURE A-3: PREDICTED MAXIMUM HORIZONTAL WAVE FRONT ENCROACHMENT 

263 
L.U 

U 

Z 

« 

o 

L.U 

L.U 

U 

X 

L.U 

.------~-- 1 -1'--. 

! 

-j I . -., 

I, , 

--f-=.- -.. ~ .. - ':.: ; 

-~.--.---~-

EAST BEACH-

" 06 1---- ---

I " I f 'I -. - ... - ... --_._-j-_._- I ~: :: I "' 

I ! , 

I 

I 

'I ,. ~ .-------,-- - . - - f ~-+- . --------.- _._-- ! I' . ': \' ' 

···-----r---·- • ,'-- --.... • . 1 - .~ .. , ... ---_. _._L. -'---

I, 

f--.- - .. ---- ----- ---. ~---l ------1----- . \ 

f---.-------4--- .-.. --.. --

II . 

0- 0 

. 

. '

,.06 

+--ui:-l- I 

I----+-T! - .----~>-\-- MIRAMAR BEACH - : L .". • I· \ I . ; 

1----:- --+---.... - r~"---- -;--r-----t-.-- I :-. I 

Ii,' .;. 

I : -.; 1 ~. /)<l fo-- ---4--.--_.--- t:- '.~ ~I ------ .. - ---·-i-----·_·---t·_·--c.--.--.J:!. --~ ... _- . ---

o 

iI. 06 

• .. 1 

~. -' ----.- -.. ------.-- -~. -·.'~:r _._- ---T -------- - --- f- ._ .... ~.- i' - -.. - t-·--_· .. . I I 

o 

-----·':'·r-

! 

I ------r------. 

_1. _~. \ ! • 

~ . t --- .... : .. , '. 

\ . ~. 

\ ... _-- ... -

.IS-

- t- -----1------

I I 

CARPINTERIA BEACH 

... ,_._--

VERTICAL WAVE FRONT ENCROACHMENT (FT) 

/O() 

F1CURE A-4: PREDICTED MAXIMUM VERTICAL WAVE FRONT ENCROACHMENT 

264 
TABLE A-1 

Predicted Critical Vave Front Encroachment under Design Storms 

Return Interval East Beach Miramar B. Carpinteria B. 

(Years) 

15 230 11. 7 220 11. 6 216 11.4 

25 275 12.3 264 12.3 255 12.2 

50 310 12.9 298 12.9 286 12.9 

100 325 13.3 313 13.3 300 13.2 

Note: All the encroachment values are in feet referenced to the 

mean sea level (MSL) shoreline. 

VH= Horizontal critical wave front encroachment 

VV= Vertical critical wave front encroachment 

265 
APPENDIX D 

AN EXAMPLE OF THE USE OF KONTE CARLO ANALYSIS 

267 
APPENDIX D 

AN EXAMPLE OF THE USE OF MONTE CARLO ANALYSIS 

The following is an example of a Monte Carlo simulation employed in the 

Final Feasibility Report on Hurricane Protection and Beach Erosi9n Control. 

West Onsl9w Beach and New River Inlet. N9rth Carolina (T9psail Beach). Monte 

Carlo simulation was used in this case because without-project conditions 

could not be calculated in the same manner as in more typical shore protection 

evaluations. Only the section of the Topsail Beach report dealing with Monte 

Carlo simulation (i.e., the estimation of without-project average annual 

damages for one reach) is summarized below. For gr~ater detail on other 

aspects of the study the reader should consult the final feasibility report 

and supporting documentation. 1 

PROBLEM SETTING 

In one of the Topsail Beach study area planning reaches, a number of 

finger canals were located behind the shore front on the mainland side of the 

barrier island. Access to the finger canals was provided through an adjacent 

inlet. Because the amount of land area between the shore front and the canals 

was less than 200 feet, coastal engineers predicted that the land buffer would 

be breached by a 30-year storm (or one of a greater exceedance interval). All 

properties located on the finger canals would be destroyed by storms of that 

magnitude. If the area were breached under the without-project condition, it 

1 U.S. Army Engineer District Wilmington, Final Feasibility Report and 

Environmental Impact Statement on Hurricane Protection and Beach Erosion 

Control. West Onslow Beach and New River Inlet. North Carolina (T9psail 

Beach), (Wilmington, NC: CESAW, 1990). 

269 
was reasoned that permits would D2t be granted to restore the area to include 

the finger canals to the pre-storm condition. Regulatory staff advised that a 

permit to fill the beach in solid (i.e., without canals) and reconstruct the 

homes probably would be issued, consistent with the historical precedent in 

other areas. This would create a development layout that would hencef~rth be 

less vulnerable to future storm damages. 

However, the fact that without-project conditions were not. static 

created a unique problem in identifying the average annual damages in the 

canal area. For anyone year, the amount of expected annual damages would 

depend on whe.ther the evaluation was done before or after a 30-year or greater 

storm event had occurred. The overall ca1,culation was dependent, therefore, 

not only on the exceedance frequency of the 30-year or larger storm, but also 

on the simulated timing of such a storm during the planning hori~on. For the 

50-year period of analysis used for proje~t evaluation, Wilmington District 

used a Monte Carlo technique to simulate when a 30-year or greater storm might 

occur. 

APPLICATIOW OF HOWl.E CARLO SIMULATION 

Monte Carlo simulation uses randomly generated numbers to simulate the 

occurrence of various storm events. Random numbers ranging from 1 to 1000 

were used to simulate one storm occurrence per year. The probability of a 30-

year or greater intensity storm occurring is 3.33 percent .in a given year. In 

this case, this translated to 33 when multiplied by 1000, to accommodate the 

use of random numbers between 1 and 1000. Thus, 33 became the key number ;in 

the search for a simulated storm sufficiently large to create a blowout (i.e., 

breach) in. the canal area. 

270 
For each "trial," random· numbers were.generated until a number less than 

or equal to 33 was found. Each number generated represented one year in the 

period of analysis. Thus the number of draws, or numbers generated, until a 

number of 33 or less was found indicated the number of years from the base 

year that the simulated storm would occur. The without-project damage 

calculation for that trial was computed in the following four-step process. 

(Example calculations are presented in the· following section). 

In the first step, the present worth of expected damages occurring prior 

to the blowout were calculated. Under existi.ng canal development conditions 

the average annuli I damages that would result from storms with exceedance 

frequencies less· than 30 years were estimated' to be $327,300. These liverage 

annual damages did not include the $12.8 million loss of the entire structural 

and content value of the canal area that would occur with a 30-year or greater 

storm. For each year prior to the blowout, the $327,300 in annual damages 

were discounted back to the base year on the basis of the present value of an 

annuity of one per year. 2 

In the second step, $4.3 million in costs for refilling the breach and 

restoring the existing infrastructure·were added to the $12.8 million in total 

damages resulting from loss of the entire canal area. Details on the cost of 

refilling the breach and restoring the infrastructure appear in the report's 

supporting documentation. Thus, th~ total damage figure for the breach was 

about $17.1 million. This total was brought back to present worth according 

2To expedite their calculations, Wilmington District used average annual 

damage estimates from all storms with an exceedance frequency of less than 30 

years for the pre-blowout condition and average annual damage estimates from 

all storms for the post:-blowout condition (described' in step 3). The more 

typical Monte Carlo approach would be to estimate for each year the specific 

damages that would result from the storm event associated with the frequency 

of the randomly generated number, under both pre- and post-blowout conditions; 

and then to determine the present worth of these storm specific, rather than 

average annual damage estimates. 

271 
to the number of years from the base year that the simulated storm had 

occurred. 

In the third step the present worth of expected damages that would occur 

after the blowout were calculated. It was assumed that the same types and 

values of homes would be rebuilt on a solid land mass following th, refilling 

-i 

of the breach. Under these post-blowout conditions, average annu~l damages 

were estimated to be $355,100, and included the entire range of storm 

freguencies in their calculation. It was the inclusion of all storm 

frequencies in this calculation that generated greater average annual damages 

than the $327,300 from the first step. 

Fourth, the present value of the total damages from steps 1-3 was 

annualized based on an 8 7/8 percent interest rate and a 50-year project life 

to reflect equivalent annual damages for that trial. 

The above process provides an estimate of the equivalent annual damages 

that would result from one 50-year series of simulated storm events (i.e., one 

game or trial in Monte Carlo vernacular). As noted in the general discussion 

of the Monte Carlo Technique, an overall estimate of the desired variable (in 

this case equivalent annual damages) is calculated by repeating the process 

many times and averaging the overall results. For this particular study, the 

process was replicated 20 times. That is, 20 sets of random numbers were 

generated, simulating for each trial when a blowout would occur. Steps 1-4 

then were repeated 20 times to estimate the equivalent annual damages for each 

trial. Dividing the sum of equivalent annual damages from all of the trials 

by 20 (i.e., obtaining the average of the equivalent annual damages estimates 

for the 20 trials) resulted in estimated equivalent annual damages of $708,800 

for the without-project condition in the canal area. 

272 
SAMPLE CALCULATIONS 

Calculations from the first two trials of the Monte Carlo simulation are 

presented below to aid in the understanding of this methodology. In the first 

trial, the third randomly generated number was the number five. Because the 

random number was less than 33, this represented an event of greater intensity 

than a 30-year frequency storm. Since it occurred in year three, the 

appropriate calculations for the equivalent annual damages would follow the 

procedure outlined in Table D-1 below. 
(1) First 3 Years 

TABLE D-13 

FIRST TRIAL 

$327,300 X 2.5369 (P.V. of annuity of l/yr for 3 yrs.) 

(2) The Blowout 

$17,074,000 X .7748 (P.V.--3 yrs.) 

(3) Next 47 Years 

$355,100 X 11.0605 X .7748 

(P.V. of Ann. of 1/yr--47 yrs.)(P.V.--3 yrs.) 

(4) Annualizing the Total 

Times .090032 (I&A 8 7/8% for 50 yrs.) 

First Trial Equivalent Annual Damages 

Present Value 

of Damages 

$830,000 

- $13,228,900 

$3,043,100 

$17,102,300 

X .090032 

$1,539,800 

Note: Included in the parentheses are the descriptions of the discounting 

factors used in the analysis. All were based on an 8 7/8% interest rate. 

P.V. refers to present value. I&A is the capital recovery factor. For a more 

complete discussion of discounting procedures see Chapter XI of the Urban 

Flood Damage Manual. 

In the second trial the number equal to or less than 33 in the random 

sample occurred on the twenty-seventh draw (Le., in year 27). The equivalent 

annual damage calculations for this trial are presented in Table D-2 below. 

3 The damage calculations presented in Tables D-1, D-2 and D~3 and 

illustrated in Figure D-1 are reproduced directly from the Supporting 

Documentation for the West Onslow Beach and New River Inlet. North Carolina 

(ToPiai1 Beach) report. The damage calculations are slightly overestimated 

because the damages for pre-blowout conditions are estimated to occur in t 

(year of blowout) time periods. Since the blowout is assumed to occur in year 

t, pre-blowout damages only should be included for t-1 time periods. 

274 
(1) First 27 Years 

TABLE D-2 

SECOWD TRIAL 

Present Value 

of Damages 

$327,300 X 10.1332 (P.V. of annuity of l/yr for 27 yrs.) - $3,316,600 

(2) The Blowout 

$17,074,000 X .10068 (P.V.--27 yrs.) 

(3) Next 23 Years 

$355,100 X 9.6736 X .10068 

(P.V. of Ann. of 1/yr--23 yrs.)(P.V.--27 yrs.) 

(4) Annualizing the Total 

Times .090032 (I&A 8 7/8% for 50 yrs.) 

Second Trial Equivalent Annual Damages 

(5) Averaging the Equivalent Annual Damages 

Total for the Two Trials ($1,539,800 + $484,500) 

Divided by Number of Trials . 

Equivalent Annual Damages After Two Trials 

- $1,719,000 

$345,800 

$5,381,400 

X .090032 

$484,500 

- $2,024,300 

/2 

$1,012,150 

Graphically, this second trial of the Monte Carlo simulation is portrayed 

in Figure D-1 below. 

Figure D-1 

Equivalent Annual Damages (Without-Project Conditions) 

Second Trial, Monte Carlo Simulation 

I 

_. . ............................................. H$1~~:;:::O + .......................... . I 

I ............................................................................................. I 

I ............................................................................................. 

• ................................................ 1 .......................................... .. 

Equlvllent AnnulI Dlmlges • Equlvllent AnnUlI Dlmages I Storms 1-27 Vel,. I All Storms • .. .. • • ... • .... ·lS4tfM·I!IIdWOl/t· ..... , .......... i .. . .. ... .. .... An.l'"B~llt .. • .. •• • ...... .. 

$327,300 I $355,100 

I 

" " .... " .. " "" " "" " "" """" "" " "" ,,"" " "" " "" " "" " "" " ,," " "". "" " "" " "" " "" ",," " "" ",," .. ,," """ " """ "" " "" ... " " " .",,"" 

27 

VHr Of Project life 

275 

so 
Table 0-3 lists the equivalent annual damages that resulted from each of 

the 20 trials of the Monte Carlo simulation. 

TABLE D-3 

SUHKARY OF TRIALS 

Trial Year of Equivalent 

Number Blowo'at Annual Damages 

1 3 $1,539,800 

2 27 484,500 

3 12 891,200 

4 4 1,441,000 

5 N.A. (>50) 327,300 

6 7 1,190,000 

7 N.A. (>50) 327,300 

8 30 449,000 

9 19 638,100 

10 6 1,266,800 

11 50 348,700 

12 50 348,700 

13 36 400,200 

14 N.A. (>50) 327,300 

15 9 1,055,100 

16 10 995,800 

17 14 802,900 

18 N.A. (>50) 327,300 

19 27 484,500 

20 24 ~~QI2QQ 

$14,175,700 

~ 20 

- $708,800 

Note: N.A. (>50) indicates that none of the 50 numbers randomly generated for 

that trial was the number 33 or less. Thus, for that trial, a simulated 

blowout did not occur during the 50 year period of analysis. 

In summ~ry, this procedure was required because of the dual damageable 

conditions in the canal area under the without-project condition. The 

"composite" .quiva1ent annual damages for this area were estimated at 

$708,800. 

276 
ORlD 

Nafioha I {conotri ie Devel0f"hei1+ 

P/2ocedUEes manual - (!OC/5+a( 

S-foR-h'I Dama!}e and f/2.-OStolj 

S EPA RAT 0 R 

C!/-!2-6 

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