U.S. Department of Interior

U.S. Geological Survey

Prepared in cooperation with the

A Precipitation-Runoff Model for

Analysis of the Effects of Water

Withdrawals on Streamflow, Ipswich

River Basin, Massachusetts

Water-Resources Investigation Report 00-4029

MASSACHUSETTS DEPARTMENT OF ENVIRONMENTAL MANAGEMENT, and the

MASSACHUSETTS DEPARTMENT OF ENVIRONMENTAL PROTECTION
Cover Photos: View of the Ipswich River between Russell 

Street and the South Middleton Dam. Normal streamflow in 

this reach is shown in the bottom left photo. Dry riverbed 

photo taken during the summer drought of 1999. 

Photo courtesy of David Armstrong and Timothy Driskell, 

U.S. Geological Survey, Northborough, Mass.
U.S. Department of Interior

U.S. Geological Survey

A Precipitation-Runoff Model for 

Analysis of the Effects of Water 

Withdrawals on Streamflow, Ipswich 

River Basin, Massachusetts

By PHILLIP J. ZARRIELLO and KERNELL G. RIES, III

Water-Resources Investigation Report 00-4029

Prepared in cooperation with the

MASSACHUSETTS DEPARTMENT OF ENVIRONMENTAL MANAGEMENT and the 

MASSACHUSETTS DEPARTMENT OF ENVIRONMENTAL PROTECTION

Northborough, Massachusetts

2000
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of trade or product names in this report is for identification 

purposes only and does not constitute endorsement by the 

U.S. Geological Survey.

For additional information write to: Copies of this report can be purchased 

Chief, Massachusetts–Rhode Island District U.S. Geological Survey

U.S. Geological Survey Information Services

Water Resources Division Box 25286

10 Bearfoot Road Denver, CO 80225-0286

Northborough, MA 01532
Con

CONTENTS

Abstract .............................................................................................................................................................................

Introduction .......................................................................................................................................................................

Purpose and Scope ..................................................................................................................................................

Previous Investigations............................................................................................................................................

Acknowledgments ...................................................................................................................................................

Description of the Basin....................................................................................................................................................

Water Withdrawals ............................................................................................................................................................

Precipitation-Runoff Model ..............................................................................................................................................

Functional Description of the HSPF Model............................................................................................................

Data Base.................................................................................................................................................................

Streamflow Data ............................................................................................................................................

Meteorologic Data.........................................................................................................................................

Water-Withdrawal Data .................................................................................................................................

Representation of the Basin.....................................................................................................................................

Hydrologic Response Units...........................................................................................................................

Impervious Areas (IMPLNDs) ............................................................................................................

Pervious Areas (PERLNDs) ................................................................................................................

Development of PERLND Types ..............................................................................................

Residential Areas on Public Water and Onsite Septic Systems.................................................

Stream Reaches .............................................................................................................................................

Hydraulic Characteristics (FTABLEs) ................................................................................................

Wetlands ..............................................................................................................................................

Water Withdrawals ..............................................................................................................................

Streamflow Depletion by Ground-Water Withdrawals..............................................................

Water Withdrawals in Excess of Streamflow.............................................................................

Model Calibration ...................................................................................................................................................

Mean Annual Discharge ................................................................................................................................

Monthly Mean Discharge and Seasonal Water Budgets ...............................................................................

Daily Flow.....................................................................................................................................................

Flow Duration......................................................................................................................................

Low Flows...........................................................................................................................................

Miscellaneous Discharge Measurements ......................................................................................................

Summary of the Differences Between Simulations with Reading and Centroid Precipitation Data ............

Sensitivity Analysis .................................................................................................................................................

Response of Pervious (PERLNDs) and Impervious (IMPLNDs) Land Segments .......................................

Parameter Values ...........................................................................................................................................

Model Limitations ...................................................................................................................................................

Application of the Model: Effects of Water Withdrawals on Streamflow.........................................................................

Calibration-Period Simulations ...............................................................................................................................

Long-term Simulations............................................................................................................................................

Summary ...........................................................................................................................................................................

References .........................................................................................................................................................................

Appendix A: Documentation of Computer Program STRMDEPL—A Program to Calculate Streamflow 

Depletion by Wells Using Analytical Solutions ..................................................................................................

Appendix B: Ipswich River Watershed Model (HSPF) User Control Input File for PERLND and IMPLND Blocks.....
IV Contents

FIGURES

1–5. Maps showing:

1. Location of the Ipswich River Basin and meteorologic sites in northeastern Massachusetts 

and southern New Hampshire and Maine .................................................................................................

2. Towns, drainage network, and stream gaging-stations in the Ipswich River Basin ..................................

3. Generalized surficial geology of the Ipswich River Basin ........................................................................

4. Wetlands in the Ipswich River Basin.........................................................................................................

5. Generalized 1991 land use in the Ipswich River Basin.............................................................................

6. Graph showing monthly mean streamflows and cumulative monthly mean withdrawals at (A) South 

Middleton station, (B) Ipswich station, and (C) cumulative monthly mean withdrawals at Sylvania 

Dam, 1989–93....................................................................................................................................................

7. Schematic of inflows to and outflows from a stream reach (RCHRES) in the Hydrological

Simulation Program-FORTRAN (HSPF)..........................................................................................................

8. Map showing model reaches, subbasin boundaries, and water withdrawal locations in the 

Ipswich River Basin...........................................................................................................................................

9–27. Graphs showing:

9. Combined actual and 15-day moving average daily ground-water withdrawals from two Wenham 

water supply wells, and the calculated streamflow depletion in Idlewild Brook, Mass., 1989.................

10. Areas of hydrologic response units in the Hydrological Simulation Program-FORTRAN (HSPF) 

model of the Ipswich River Basin as a percentage of the drainage area above the South Middleton and 

Ipswich stations and above Sylvania Dam ................................................................................................

11. Ground-water flow paths illustrating captured recharge and induced infiltration in a hypothetical 

aquifer: (A) undeveloped aquifer, (B) pumped well with a high water table, (C) pumped well with 

a low-water table surface, and (D) changing storage when withdrawals exceed captured recharge 

and induced infiltration..............................................................................................................................

12. Actual water withdrawals and the withdrawals satisfied by streamflow in the Hydrological 

Simulation Program-FORTRAN (HSPF) in reach 1 of the Ipswich River Basin for the period 

June 1, 1991 through August 31, 1991......................................................................................................

13. Relation of simulated mean annual discharge to observed for simulations made with centroid and 

Reading precipitation data for the Ipswich River at (A) South Middleton station, and (B) Ipswich 

station, 1989–93 ........................................................................................................................................

14. Relation of simulated monthly discharge to observed for simulations made with centroid and

Reading precipitation data for the Ipswich River at (A) South Middleton station, and (B) Ipswich 

station, 1989–93 ........................................................................................................................................

15. Percent error between simulated flow made with the centroid precipitation data and observed flows 

for the Ipswich River at the (A) South Middleton, and (B) Ipswich stations by month, before and after 

adjusting evapotranspiration rates for seasonal bias, 1989–93 .................................................................

16. Simulated daily mean discharge to observed for simulations made with centroid and Reading 

precipitation data for the (A) South Middleton, and (B) Ipswich stations, Ipswich River, 1989–93 ........

17. Simulated and observed daily-mean-discharge hydrographs for simulations made with centroid 

precipitation data at the (A) South Middleton, and (B) Ipswich stations, Ipswich River, 1989–93 ..........

18. Difference between simulated and observed daily mean discharges as a function of time at the 

(A) South Middleton, and (B) Ipswich stations, Ipswich River, 1989–93.................................................

19. Difference between simulated and observed daily mean discharges as a function of observed 

discharge at the (A) South Middleton, and (B) Ipswich stations, Ipswich River, 1989–93.......................

20. Observed and simulated daily mean discharge at the Ipswich station for simulations made with the 

centroid precipitation, air temperature, and simulated snowpack water for the Ipswich River Basin, 

February through April 1993.....................................................................................................................

21. Flow-duration curves for observed and simulated daily mean discharges for simulations made 

with the centroid and Reading precipitation data for the (A) South Middleton, and (B) Ipswich

stations, Ipswich River, 1989–93 ..............................................................................................................

22. Discharge simulated with centroid and Reading precipitation data and instantaneous discharge 

measurements made at Fish Brook near Boxford, July 1993....................................................................
Con

23. Runoff as surface-flow, interflow, and base-flow and evapotranspiration losses from surface storage, 

upper-zone storage, lower-zone storage, and ground-water storage from each hydrologic response

unit for: (A) mean annual water budget, (B) wet month water budget—April 1993, and (C) dry 

month water budget—August 1993, Ipswich River Basin........................................................................

24. Flow-duration curves developed from simulated daily flows for current conditions (base simulation), 

no withdrawals, only surface-water withdrawals, and only ground-water withdrawals for the 

Ipswich River at the (A) South Middleton and (B) Ipswich stations, 1989–93.........................................

25. Hydrographs for current conditions (base simulation), no withdrawals, only surface-water 

withdrawals, and only ground-water withdrawals for the Ipswich River at the (A) South Middleton 

and (B) Ipswich stations, 1989–93 ............................................................................................................

26. Flow-duration curves for average water withdrawals with 1991 land-use conditions, no withdrawals 

with 1991 land-use conditions, and no withdrawals with undeveloped land-use conditions for the 

Ipswich River at the (A) South Middleton, and (B) Ipswich stations for long-term simulations 

(1961–95) ..................................................................................................................................................

27. Log-Pearson Type III low-flow exceedence probabilities and recurrence intervals for (A) 1-day, 

(B) 7-day, and (C) 30-day annual minimum mean streamflows based on long-term (1961–95) 

simulations of average water withdrawals, no withdrawals with 1991 land-use conditions, and no 

withdrawals with undeveloped land-use conditions, for the Ipswich River at the South Middleton 

and Ipswich stations ..................................................................................................................................

TABLES

1. Monthly mean streamflow at the South Middleton and Ipswich stations, and cumulative monthly mean 

water withdrawals to the stations and Sylvania Dam, Ipswich River Basin, Mass., 1989–93............................

2. Organization and description of Data Set Numbers (DSNs) in the Watershed Data Management (WDM) 

system for the Ipswich River Basin ....................................................................................................................

3. Meteorologic stations and data used to develop grid-cell data for the Ipswich River Basin, Mass....................

4. Summary of municipal water-use information in the Ipswich River Basin........................................................

5. Massachussets Department of Environmental Protection registered or permitted public and commercial 

water withdrawals in the Ipswich River Basin....................................................................................................

6. Estimated effective impervious area by land use, Ipswich River Basin .............................................................

7. Hydrologic response units (HRUs) used to represent the Ipswich River Basin, and their contributing 

areas to the South Middleton and Ipswich stations, and to Sylvania Dam .........................................................

8. Stream reaches (RCHRES) in the Hydrological Simulation Program-FORTRAN model of the 

Ipswich River Basin ............................................................................................................................................

9. Deficit between actual water withdrawals and the withdrawal satisfied by streamflow in the 

Hydrological Simulation Program-FORTRAN (HSPF) for Ipswich River reaches above the South 

Middleton station, 1989–93 ................................................................................................................................

10. Summary of annual, monthly, and daily model-fit statistics at South Middleton and Ipswich stations for 

Hydrological Simulation Program-FORTRAN (HSPF) simulations made with centroid and Reading 

precipitation data, Ipswich River Basin, 1989–93 ..............................................................................................

11. Observed and simulated annual discharge at South Middleton and Ipswich stations for Hydrological 

Simulation Program-FORTRAN (HSPF) simulations made with centroid and Reading precipitation data, 

Ipswich River Basin, 1989–93 ............................................................................................................................

12. Summary of seasonal model-fit statistics at South Middleton and Ipswich stations for Hydrological 

Simulation Program-FORTRAN (HSPF) simulations made with centroid and Reading precipitation 

data, Ipswich River Basin, 1989–93 ...................................................................................................................

13. Summary of low-flow model-fit statistics at the South Middelton and Ipswich stations for Hydrological 

Simulation Program-FORTRAN (HSPF) simulations made with centroid and Reading precipitation data,

Ipswich River Basin, 1989–93 ............................................................................................................................

14. Relative sensitivity of simulated flow characteristics to HSPF model parameter or storage change, 

Ipswich River Basin, 1989–93 ............................................................................................................................

15. Sensitivity of runoff characteristics, as the percent error from the observed value, to selected model 

PERLND parameters and wetland storage values, in the HSPF Ipswich River Basin model, 1989–93 ............

16. Alternative water withdrawals and land-use scenarios simulated for the Ipswich River Basin..........................
VI Contents

CONVERSION FACTORS AND VERTICAL DATUM

CONVERSION FACTORS

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 × °C) + 32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C = (°F - 32) / 1.8

VERTICAL DATUM

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of

1929)—a geodetic datum derived from a general adjustment of the first-order level nets of the United

States and Canada, formerly called Sea Level Datum of 1929. 

Altitude, as used in this report, refers to distance above or below sea level.

Multiply By To obtain

Length

inch (in.) 2.54 centimeter

inch (in.) 25.4 millimeter

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

Hydraulic gradient

foot per mile (ft/mi) 0.1894 meter per kilometer

Area

acre 4,047 square meter

acre 0.4047 hectare

acre 0.004047 square kilometer

square mile (mi2) 259.0 hectare

square mile (mi2) 2.590 square kilometer 

Volume

million gallons (Mgal) 3,785 cubic meter 

gallon per day (gal/d) 0.003785 cubic meter per day

inch per hour per acre (in/h/acre) 10.28 meter per hour per hectare

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second 

million gallons per day (Mgal/d) 0.04381 cubic meter per second

inch per hour (in/h) 0 .0254 meter per hour

million gallons per day per square mile [(Mgal/d)/mi2] 1,461 cubic meter per square kilometer

inch per year (in/yr) 25.4 millimeter per year

Hydraulic conductivity

foot per day (ft/d) 0.3048 meter per day

Diffusivity

foot squared per second (ft2/s) 0.09290 meter squared per second 
Ab

A Precipitation-Runoff Model for 

Analysis of the Effects of Water 

Withdrawals on Streamflow, Ipswich 

River Basin, Massachusetts

By Phillip J. Zarriello and Kernell G. Ries, III

Abstract

Water withdrawals from the 155-squaremile Ipswich River Basin in northeastern 

Massachusetts affect aquatic habitat, water quality, 

and recreational use of the river. To better understand the effects of these withdrawals on streamflow, particularly low flow, the Hydrological 

Simulation Program-FORTRAN (HSPF) was used 

to develop a watershed-scale precipitation-runoff 

model of the Ipswich River to simulate its 

hydrology and complex water-use patterns.

An analytical solution was used to compute 

time series of streamflow depletions resulting from 

ground-water withdrawals at wells. The flow 

depletions caused by pumping from the wells were 

summed along with any surface-water withdrawals 

to calculate the total withdrawal along a stream 

reach. The water withdrawals, records of precipitation, and streamflow records on the Ipswich River 

at South Middleton and at Ipswich for the period 

1989–93 were used to calibrate the model. Modelfit analysis indicates that the simulated flows 

matched observed flows over a wide range of conditions; at a minimum, the coefficient of model-fit 

efficiency indicates that the model explained 79 

percent of the variance in the observed daily flow.

Six alternative water-withdrawal and landuse scenarios were simulated with the model. 

Three scenarios were examined for the 1989–93 

calibration period, and three scenarios were examined for the 1961–95 period to test alternative 

withdrawals and land use over a wider range of 

climatic conditions, and to compute 1-, 7-, 

30-day low-flow frequencies using a log-Pe

Type III analysis. Flow-duration curves com

from results of the 1989–93 simulations ind

that, at the South Middleton and Ipswich ga

stations, streamflows when no water withdr

are being made are nearly identical to stream

when no ground-water withdrawals are mad

Streamflow under no water withdrawals at b

stations are about an order of magnitude lar

the 99.8 percent exceedence probability tha

lations with only ground-water withdrawals

Long-term simulations indicate that the diff

ences between streamflow with no water wi

drawals and average 1989–93 water withdra

similar to the difference between simulation

the same water-use conditions made for the 

93 period at both sites. The 7-day, 10-year 

low-flow (7Q10, a widely used regulatory st

at the South Middleton station was 4.1 cubi

per second (ft3/s) with no water withdrawal

1991 land use, 5.8 ft3/s no withdrawals and 

veloped land, and 0.54 ft3/s with average 19

water withdrawals and 1991 land use. The 7

the Ipswich station was about 8.3 ft3/s for s

tions with no water withdrawals for both th

land use and the undeveloped land condition

2.7 ft3/s for simulations with average 1989–

water withdrawals and 1991 land use. Simu

results indicate that surface-water withdraw

have little effect on the duration and freque

low flows, but the cumulative ground-water 

withdrawals substantially decrease low flow
2 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

INTRODUCTION

Water use in the Ipswich River Basin has been a 

subject of contention since the early 1900’s, when several surrounding towns were first granted rights by the 

Commonwealth of Massachusetts to transfer water 

from the 155-square-mile basin for municipal supplies. 

The debate over water intensified during the 1990’s as 

development and demand for water increased. The 

debate centers on whether water withdrawals have 

decreased or will decrease flows of the Ipswich River 

enough to cause degradation of water quality, loss of 

wildlife habitat and diversity, and diminished capacity 

for use of the river as a recreational and scenic 

resource. The debate is particularly focused on conditions during summers, when at times nearly half of the 

45-mile-long river goes dry.

Dry conditions during the summer of 1997 may 

have prompted the national environmental organization, American Rivers, to designate the Ipswich River 

as one of the 20 most threatened rivers in the United 

States during that year. American Rivers cited water 

withdrawals, development, and pollution as reasons for 

the designation, stating that "so much water is removed 

from the Ipswich River watershed for municipal water 

supply, industry, and irrigation that the river can literally run dry" (American Rivers, http://www.amrivers.org/). The river is listed under Section 303(d) of the 

Federal Clean Water Act as a water body that is not in 

compliance with the Massachusetts Water Quality 

Standards. The reasons for the listing are impairment of 

flow, low concentrations of dissolved oxygen, high 

concentrations of nutrients, and the presence of pathogens (Massachusetts Department of Environmental 

Protection, 1999). The U.S. Environmental Protection 

Agency (USEPA) requires Massachusetts to develop 

management plans for the Ipswich River to address 

non-compliance with water-quality standards.

Recognizing that any solution to bring the river 

into compliance with water-quality standards will 

require cooperation among the many stakeholders, a 

group of representatives from several Federal, State, 

and local environmental agencies, non-governmental 

environmental groups, water suppliers, and private citizens formed the Ipswich River Task Force in 1996, 

herein referred to as the Task Force. The goals of the 

Task Force are to assess the water-resource problems in 

the basin and to facilitate solutions.

The Task Force determined that a watersh

model was needed to serve as a basis for waterresources-management decisions in the basin (P

Phippen, Massachusetts Department of Environ

Management, written commun., 1997). A water

model would allow State planning and regulator

cies to: (1) determine potential effects of action

ciated with increased human development on w

resources, (2) make decisions on permitting of e

and new water withdrawals, (3) set streamflow 

dards to protect biota in the river, (4) determine 

yields of water-supply reservoirs in the basin, a

(5) develop a management plan that will lead to 

pliance of the river with the Massachusetts Wat

Quality Standards.

The U.S. Geological Survey (USGS), in c

eration with the Massachusetts Departments of 

Environmental Management (MADEM) and 

Environmental Protection (MADEP), began dev

ing a watershed model for the Ipswich River Ba

in September 1997. The goal of this effort was 

provide a tool that could be used by the various 

stakeholders to assess water-resources issues in 

the basin. 

Problems associated with water use and u

ization in the Ipswich River Basin are not uniqu

Recent State legislation (Senate Bill No. 2006 a

House Bill No. 4791) established ‘A Water Res

Conservation Act and Efficiency Program’ and 

fied the Ipswich River Basin water-managemen

program as a model for other basins throughout 

State in recognition of the efforts already under

by the Task Force. This legislation requires wat

management programs for estimating long-term 

needs and determining discharges sufficient to p

aquatic life. The development of watershed sim

models will help address these issues.

Purpose and Scope

This report describes the development, ca

tion and limitations of a precipitation-runoff mo

the Ipswich River Basin, and simulations made 

the model to determine the effects of water-use 

land use patterns on streamflows. The report als

describes the study area, which consists of the 1

square-mile drainage area above the Sylvania D

Ipswich; the data used in the model and the met

used to obtain those data; and the methods used 
Introd

estimate the effects of the pumping of wells on streamflow. Results of the simulation of six scenarios that test 

different water-withdrawal operations and land-use 

patterns are described; three scenarios were simulated 

for the 1989–93 calibration period and three were simulated for the 1961–95 period to examine the effects of 

withdrawals and land-use change over a wider range of 

climatic conditions.

Previous Investigations

Numerous reports have been written on the water 

resources of the Ipswich River Basin by State environmental agencies, regional-planning agencies, nongovernmental environmental organizations, and the 

USGS. Relevant reports are summarized below. 

Baker and others (1964) described the geology 

and ground water of the Wilmington-Reading area. 

They identified areas within the towns where there was 

potential for installing municipal wells with substantial 

yields, and they also described potential negative 

effects on well yields of a then-proposed draining of 

adjacent wetlands.

Sammel and others (1964) provided a synopsis 

of the water resources in the basin. Their synopsis 

included information on precipitation, streamflows, 

ground-water levels, and water use, and a map showing 

availability of ground water and locations of municipal 

wells in the basin. In a later report, Sammel and others 

(1966), provided a more detailed analysis of the water 

resources than in the earlier report. The later report 

included a revised map of ground-water availability 

and locations of municipal wells, and maps of surficial 

geology and depth to bedrock. They indicated that the 

basin could sustain water withdrawals of about five 

times the 1960 rate of 7.6 ft3/s, but that these withdrawals would need to come primarily from downstream 

reaches of the river. They also noted that a basin-wide 

approach to the hydrologic problems of the basin was 

needed along with a better understanding of the hydrologic connection between ground- and surface-water 

resources.

Burns and James (1972) developed a streamflowaccounting model of the basin to address many of the 

same issues described in this report. The model was 

simplistic by comparison with current standards, however, and its ability to address complex hydrologic 

problems was limited. For example, the model 

lated streamflow in subbasins with the streamflo

unit drainage area that was measured at the gag

tions, and thus, the model did not account for d

ences in the land use or physical properties of th

subbasins. Further, the model simulated stream

with a monthly time step that is inadequate for 

ing the magnitude and frequency of low flows.

Reports by state agencies include those b

MADEM (1987a, 1987b, and 1999), which pro

three-volume management plan for the Ipswich 

Basin in the late 1980s. Volume I of the plan co

an inventory and analysis of current and project

water use. Volume II contained hydrologic anal

and recommendations for minimum streamflow 

olds. The report recommended a streamflow of 

0.14 (Mgal/d)/mi2 of drainage area. This transla

flows of 9.6 ft3/s at the South Middleton gaging 

27 ft3/s at the Ipswich gaging station, and 33.5 

the Sylvania Dam in Ipswich. Volume III of the 

recommended alternatives for meeting water de

Relevant reports by regional planning agencies 

included those by the Metropolitan Area Planni

Council (1977) and the New England River Bas

Commission (1975).

The Ipswich River Watershed Association 

released several reports on water-resources con

in the basin. The Association releases an annua

on activities of the River Watch volunteer moni

program, which monitors flow and water qualit

about 25 locations. In the summer of 1997, the 

Association documented the absence of flow al

large stretches of the river, reversed flow toward 

upstream municipal wells in some areas, and de

dissolved oxygen at several locations (Ipswich 

Watershed Association, 1998).

Bratton (1991) summarized water use by 

for the Commonwealth of Massachusetts, inclu

that for towns that obtain water from the Ipswic

Basin (p. 53, 56–59). Simcox (1992) summarize

resources and streamgaging activities in the stat

including those in the Ipswich River Basin (p. 3

In addition, nearly all the towns in the area have 

by consulting engineers describing potential wa

supply and distribution alternatives.
4 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Acknowledgments

The authors would like to thank water suppliers 

that provided water-use information. The authors are 

also very grateful to the numerous individuals who provided information or comments during the study 

including Peter Phippen and Victoria Gartland of the 

MADEM, Arthur Screpetis, Duane LeVangie, Thomas 

Lamonte, and Stephen Hallem of the MADEP, Kerry 

Mackin and Daniele Lantagne of the Ipswich River 

Watershed Association, and Richard Tomczyk of the 

Massachusetts Executive Office of Environmental 

Affairs. Robert Lautzenheiser supplied precipitation 

information and Luc Claessens of the Marine 

Biological Laboratory, Woods Hole, Mass., obtained 

and processed most of the climate data used in the 

study. Tom Jobes of Aqua Terra, Inc., answered numerous questions about the HSPF model code and developed the procedure to account for water withdrawals in 

excess of streamflow. In addition, the authors would 

like to thank employees of the USGS who helped to 

collect and analyze data for the study, and who helped 

to prepare this report. The authors are especially grateful to Paul Barlow of the USGS for developing the 

STRMDEPL program that was used to calculate the 

effects of ground-water withdrawals on streamflow.

DESCRIPTION OF THE BASIN

The Ipswich River Basin encompasses a 155-

square-mile area in the Atlantic coastal plain in northeastern Massachusetts about 20 miles north of Boston 

(fig. 1). The western headwaters of the Ipswich River 

begin in northern town of Burlington in the Mill Brook 

tributary, about 25 miles southwest of its mouth at the 

Atlantic Ocean near the southern tip of Plum Island 

(fig. 2). The basin is generally 5 to 10 miles wide in the 

north-south direction. The Ipswich River is affected by 

tide below the Sylvania Dam (fig. 2); this reach of the 

river and its associated drainage area were not included 

in the study area. 

A number of constructed features affect t

hydrology of the basin. Most of the large water 

in the basin were built for water-supply storage n

headwaters of several small tributaries (fig. 2). 

moderate-size reservoirs were built along the m

tributary streams to supply water or power to fo

mills, or for recreation. These impoundments st

waters during periods of high flow and increase 

potential for evaporation.

Climate: The climate in the basin is humi

an average annual air temperature of 49 ̊F for th

period 1961–95. Monthly mean temperatures d

this period ranged from 25 ̊F in January to 71 ̊F 

During the study period of 1989–93, the averag

temperature was also 49 ̊F; the monthly mean t

tures for this period ranged from 28 ̊F in Februa

70 ̊F in July and August.

Precipitation during the period 1961–95 

averaged 45 in/yr. Precipitation was distributed 

evenly throughout the year, with average month

cipitation ranging from 3.2 inches in July to 4.8 

in November. Precipitation during the study per

very similar. Annual precipitation during 1989–

averaged 46 inches, and monthly precipitation r

from 3.0 inches in May and July, to 4.8 inches i

October. Annual snowfall during 1989-93 avera

37 inches, and ranged from 22 inches in 1991 to 

83 inches in 1993.

Towns: The Ipswich River Basin includes 

parts of 22 municipalities (fig. 2). Of these, only 

(Middleton, North Reading, and Topsfield) are 

within the basin. Boxford, Hamilton, Ipswich, 

Lynnfield, North Andover, Wenham, and Wilmi

are mostly within the basin. About half or less th

of Andover, Beverly, Burlington, Danvers, Peab

and Reading are in the basin, and less than 1 m

Billerica, Essex, Georgetown, Rowley, Tewksbu

Woburn are in the basin. These municipalities o

water supplies from various sources both inside 

outside of the basin.
Description of the 

Bedford

Groveland

Dracut

Haverhill

Ipswich

Marblehead

Natick

Newburyport

Peabody Reading

Ro

Salem

Weston

Concord

Windham

Hudson

Greenland

Epping

Durham

Chestnut

Hill

Spot

Pond

Massabasic

Lake

Middleton

Lawrence

Lowell

Nashua

Manchester

Portsmo

BOSTON

WORCESTER

Plum

Island

ATLANT

OCEAN

IPSWICH RIVER BASIN

0

0 5 10 15 20 MILES

5 10 15 20 KILOMETERS

MASSACHUSETTS

NEW HAMPSHIRE

MAINE

NEW

HAMPSHIRE

EXPLANATION

IPSWICH RIVER BASIN

BOUNDARY

METEOROLOGIC SITE

AND NAMEÑ

First order National

Weather Service station

Cooperative National

Weather Service station;

Minimum and maximum

daily air temperature and

daily precipitation

(dark fill indicates

hourly precipitation

data available)

CONCORD 

71o 30' 71o 00'

43o

00'

42o

30'

Figure 1. Location map of the Ipswich River Basin and meteorologic sites in northeastern Massachusetts and souther

Hampshire and Maine.
6 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Sylvania Dam Willowdale Dam South Middleton Dam Putnamville Reservoir Swan PondEmerson Brook Reservoir Winona Pond Suntaug Lake Wenham Lake Longham Reservoir Lowell Pond Middleton Pond

Salem-Beverly Canal

Pye Bro ok

Howlett Brook

Nicho ls Brook

Fish Brook

Lubbers Brook

Ipswich

R vi

er

Black Brook

Miles River

Idlewild Brook

Emerson Brook

Boston Brook

Wills Brook

Norris Brook

River Bear Meado w Brook

Martins Brook

Cleveland Brook

a M e Mel p da wo r B koo

Mil Bl

koor

Ip ws

ci

h

HAMILTON

DANVERS

PEABODY LYNNFIELD

WOBURN

TEWKSBURY

BURLINGTON

WILMINGTON

ANDOVER

NORTHANDOVER

BOXFORD

MIDDLETON

NORTH READING

READING

TOPSFIELD

ROWLEY

IPSWICH

WENHAM

BEVERLY

SALEM

MARBLEHEAD

LYNN

ESSEX

GLOUCESTER

GEORGETOWN

BILLERICA

MANCHESTER

WAKEFIELD

SWAMPSCOTT

01102000

01101500 01101500

Ipswich Gaging 

Station

S. Middleton

 Gaging 

Station

71o10'

42o

42

30'

o

40'

70o50' 

0 24 KILOMETERS

0 2 4 6 MILES

6

Area notmodeled

EXPLANATION

STREAM-GAGING STATION AND NUMBER

01101500

BASIN BOUNDARY

DAM

ATLANTIC

OCEAN
Description of the 

Drainage and Gaging Stations: The USGS has 

operated two streamgaging stations in the basin since 

the 1930’s (fig. 2). The upstream station at South 

Middleton (station no. 01101500), operated since 

1938, is a few hundred feet below the South Middleton 

Dam and has a contributing drainage area of 44.5 mi2. 

This station is referred to in this report as the South 

Middleton station. Major tributaries above the station 

include Maple Meadow Brook, Lubbers Brook and 

Martins Brook. Average river slope above this station is 

about 6.0 ft/mi. Mean annual streamflow at South 

Middleton for the period of record is 63.7 ft3/s 

(Socolow and others, 1998).

The downstream station at Ipswich (station no. 

01102000), operated since 1930, is a few hundred feet 

below Willowdale Dam and has a contributing drainage 

area of 125 mi2. This station is referred to in this report 

as the Ipswich station.A small area (about 0.6 mi2) 

drains directly to a supply reservoir that exports water 

from the basin. Major tributaries between the South 

Middleton and Ipswich stations include Boston Brook, 

Fish Brook, and Howlett Brook. The average river 

slope between stations is about 1.5 ft/mi. The mean 

annual streamflow at Ipswich for the period of record is 

189 ft3/s (Socolow and others, 1997).

The drainage between the Ipswich station and 

the Sylvania Dam (25 mi2) is ungaged. Contributing 

drainage to Sylvania Dam is 150 mi2 and includes 

inflows from Miles River. Average river slope below 

the Ipswich station is 2.8 ft/mi. 

Topography: The Atlantic coastal plain is characterized by low relief. The Ipswich River elevation drops 

from about 110 ft at its headwaters to sea level at its 

mouth, and has an average slope of 3.1 ft/mi. Stream 

gradients are influenced by numerous wetlands and 

three low-profile dams that create flat-water conditions 

in many reaches along the river’s 36-mile length. Wetlands and dams also affect tributary stream gradients. 

Upland areas of the basin are generally low-rounded 

hills with a maximum elevation of 420 ft, but most hills 

are under 300 ft.

Surficial Geology: Glacial till covers about 54 

percent of the basin, stratified sand and gravel deposits 

cover about 43 percent of the basin, and alluvial deposits cover about 3 percent of the basin (fig. 3). Upland 

areas of the basin are mostly underlain by till, which 

consists of unsorted and unstratified materials ranging 

in size from clay to large boulders that were transported and spread over the land surface by glaciers 

(Sammel and others, 1966). Tills are highly variable in 

their material content and compactness and, thu

permeability will also differ widely. Melvin and 

(1992) report that the median hydraulic conduct

tills derived from crystalline-rock in southern N

England range from 2.7 ft/d for loose surface ti

0.6 ft/d for compact drumlin till. Till deposits al

in depth but generally are thin, and bedrock is at 

the surface in some areas mapped as till (fig. 3)

Lowland areas of the basin are generally 

lain by stratified drift, which consists of well-so

fluvial sands and gravels deposited from glacial 

water streams. The permeability of stratified dri

cally is larger than that of till. Baker and others 

report a median hydraulic conductivity of 53 ft/

coarse-grained sand and gravel. Precipitation ge

infiltrates rapidly into stratified drift and then is 

released to streams as base flow. Stratified drift 

the major aquifers in the basin, many of which 

developed for municipal water supply.

Post-glacial alluvial deposits are found m

along stream channels. These deposits are typic

fine-grained and have a low to moderate perme

Melvin and others (1992) report hydraulic cond

ties of 0.82 to 0.0001 ft/d for fine-grained drift 

its, which are probably similar to the range in hy

conductivities of the alluvial deposits because t

particle size distributions are similar.

Wetlands: Wetlands cover about 21 perce

the Ipswich Basin (fig. 4), of which 6 percent is 

forested and 15 percent is forested. The wetland 

bution is nearly the same for the drainage areas 

two streamgaging stations and for the entire bas

largest of the wetlands is Wenham Swamp, whi

occupies an area of about 3 mi2 along the Ipswi

River near the border of Hamilton and Wenham

Wetlands, especially those along the Ipsw

River, play an important role in the hydrology o

basin. Wetland soils generally have a high organ

tent, high porosity, and low permeability, thus th

store large volumes of water but do not transmi

easily to underlying deposits. Wetlands general

become inundated during floods and in the spri

retarding the magnitude and timing of peak disc

Wetlands in the Ipswich Basin are typically den

vegetated with a water table within a few feet o

land surface; these factors maximize the potent

evapotranspiration.
8 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

EXPLANATION SAND AND GRAVEL TILL AND BEDROCK ALLUVIUM BASIN BOUNDARY SUBBASIN BOUNDARY TO GAGE STREAM-GAGING STATION 71o10' 42o30 42o40' 70o50' 024 KILOMETERS 0 2 4 6 MILES

6

Figure 3. Generalized surficial geology of the Ipswich River Basin, Mass. (Location is shown in fig. 1).
Description of the 

WenhamSwamp

024 KILOMETERS

0 2 4 6 MILES

6

EXPLANATION

OPEN WATERNON-FORESTED WETLANDSFORESTED WETLANDSBASIN BOUNDARYSUBBASIN BOUNDARY TO GAGESTREAM-GAGING STATION

71o10'

42o30'

42o40'

70o50'

Figure 4. Wetlands in the Ipswich River Basin, Mass.
10 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Land use: Land use in the basin is shown in 

figure 5. The land use as a percent of the basin area is 

slightly different above South Middleton station than 

above the Ipswich station and Sylvania Dam. Land use 

as a percent of the basin area above the Ipswich station 

and Sylvania Dam are nearly identical. Land use is 

predominantly residential above the South Middleton 

station; residential areas comprise about 38 percent of 

the area above the station and about 28 percent of the 

area below the station. Commercial areas comprise 

about 6 percent of the basin area above the South 

Middleton station and about 4 percent of the area 

below the station. Forests and open space comprise 34 

percent of the basin area above the South Middleton 

station and about 44 percent of the area below the station. Open water is also somewhat less prevalent above 

the South Middleton station (1.7 percent) than below 

the station (2.5 percent). 

Stream Habitat: The stream habitat along 

most of the Ipswich River and its major tributaries is 

characterized by sand-size bed material, slow-water 

velocities, and smooth, unbroken water surfaces. Fast, 

turbulent water riffle habitats are few and tend to be 

short. The largest naturally occurring riffles are 

downstream of dams. About a dozen smaller riffles 

are associated with structures such as highway and 

railroad bridges, old mills, or areas of fill. Riffles 

have a substantial effect on water levels in the basin 

because the backwater conditions above the riffle can 

extend hundreds to thousands of feet upstream. 

Riffles are also important because the aeration of 

water across them increases the dissolved oxygen in 

stream water and provides critical habitat for many 

aquatic species. Six critical riffle habitats were identified along the main-stem of the Ipswich River. In a 

related hydrologic study, habitat assessments and discharge measurements were made over a range of flows 

at these riffles to better understand habitat availability 

under various streamflow conditions (D.S. Armstrong, 

U.S. Geological Survey, Northborough, Mass, 1999, 

written commun.).

WATER WITHDRAWALS

The Ipswich River Basin supplies water t

330,000 people (R. Tomczyk, Ipswich River Wa

Team Leader, written commun.,1999) in 21 mu

ities within or partly within the basin and 2 mun

ties (Salem and Lynn) entirely outside the basin 

In addition, the towns of Essex, Gloucester, Ma

ter, and Rockport, which are either mostly or en

outside the basin, have legislative rights to with

water from the Ipswich River, but these rights a

not currently used (Massachusetts Department 

Environmental Management, written commun., 

The total cumulative withdrawals and the 

obtained from surface- and ground-water sourc

above the South Middleton station, Ipswich stat

and Sylvania Dam are summarized in table 1 an

shown in figure 6 along with streamflow at the s

Ground-water withdrawals exceed surface-wate

withdrawals at all times above the South Middle

tion because most withdrawals are from ground

sources above this station. Below the South Mid

station, ground-water withdrawals often exceed 

face-water withdrawals from June through Octo

each year, but surface-water withdrawals excee

ground-water withdrawals from about Novemb

through May of each year. 

Municipal surface-water diversions from 

Ipswich River include the city of Lynn above th

Middleton station, and the towns of Peabody, S

and Beverly below the South Middleton station

State has regulated these diversions by water-us

mits since the early 1900’s. In general, withdraw

only permitted between December and May, an

when streamflow at the South Middleton station 

is greater than 15.5 ft3/s, except in emergency s

tions. In 1998, the minimum streamflow thresho

before water can be diverted from the river was 

changed for the Salem-Beverly supply to 43 ft3

the Ipswich station (Duane LeVangie, Massach

Department of Environmental Protection, oral 

commun., 1999). 
Water Withdra

EXPLANATION

FORESTWETLANDOPEN WATEROPEN UNDEVELOPEDLOW-DENSITY RESIDENTIALHIGH-DENSITY RESIDENTIALCOMMERCIAL / TRANSPORTATIONBASIN BOUNDARYSUBBASIN BOUNDARY TO GAGESTREAM-GAGING STATION 024 KILOMETERS

0 2 4 6 MILES

6

71o10'

42o30'

42o40'

70o50'

Figure 5. Generalized 1991 land use in the Ipswich River Basin, Mass.
12 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Table 1. Monthly mean streamflow at the South Middleton and Ipswich stations, and cumulative monthly mean water 

withdrawals to the stations and Sylvania Dam, Ipswich River Basin, Mass. 1989–93

[Values are in cubic feet per second. STRMDEPL, program used to compute the delayed effects of ground water withdrawals on streamflow; --, in

data]

Month Streamflow

Withdrawals

Surface water Actual ground 

water

Surface water 

plus actual 

ground water

STRMDEPL Surface 

plus STR

South Middleton station

January ............................ 66 0 8.8 8.8 9.1 9.

February .......................... 87 1.6 8.8 10 8.6 10

March .............................. 92 3.6 8.4 12 8.4 12

April ................................ 153 4.1 9.4 13 8.8 13

May ................................. 78 2.8 11 13 9.2 12

June ................................. 39 .52 11 12 10 10

July.................................. 7.7 .58 12 12 11 11

August ............................. 23 .50 11 11 10 11

September........................ 13 .27 11 11 11 11

October............................ 51 .12 9.1 9.3 10 10

November........................ 78 .03 8.8 8.9 9.3 9.

December ........................ 88 1.2 10 11 10 11

Mean............................ 65 1.3 10 11 9.5 11

Ipswich station

January ............................ 175 18 11 29 11 29

February .......................... 242 15 11 26 11 26

March .............................. 245 20 11 31 11 31

April ................................ 467 22 12 34 11 33

May ................................. 232 16 13 30 12 28

June ................................. 112 10 15 25 13 23

July.................................. 32 7.0 16 23 14 21

August ............................. 63 6.4 14 21 14 20

September........................ 42 5.4 14 19 14 19

October............................ 113 10 12 21 12 22

November........................ 174 23 11 34 11 34

December ........................ 212 40 12 52 12 51

Mean............................ 176 16 13 29 12 28

Sylvania Dam

January ............................ -- 24 11 35 11 35

February .......................... -- 24 11 35 11 35

March .............................. -- 29 11 39 11 40

April ................................ -- 27 12 38 11 38

May ................................. -- 21 14 35 12 33

June ................................. -- 13 16 29 13 27

July.................................. -- 8 17 25 15 23

August ............................. -- 9 15 24 14 23

September........................ -- 7 14 21 14 21

October............................ -- 15 12 27 13 27

November........................ -- 30 11 41 12 42

December ........................ -- 47 12 59 12 59

Mean............................ -- 21 13 34 12 34
Water Withdra

Surface waters can be withdrawn from reservoir 

storage between May and October, but these withdrawals are not included in table 1 or figure 6 to avoid 

double counting withdrawals from the basin. This 

includes transfers of water into Wenham Lake from 

Putnamville Reservoir and out of Wenham Lake for the 

Salem-Beverly supply, transfers of water out of Swan 

Pond and Emerson Brook Reservoir to Middleton Pond 

for the Danvers-Middleton supply, and transfers of 

water out of Winona Pond and Suntaug Lake for the 

Peabody supply. These rates do not include some small 

commercial withdrawals because data was not available, however, their total withdrawals are believed to 

be minor relative to the water use data summarized 

in the study.

 The net effect of the withdrawals on the river 

flow at any given time depends on the timing of 

surface-water withdrawals, along with the delayed 

effects of ground-water withdrawals, which are 

erned by aquifer properties and the location of t

relative to the river. Therefore, depletions of str

flow caused by ground-water pumping generall

less than actual pumping rates during the spring 

summer, and greater than actual pumping rates 

the fall. In addition, some of the withdrawn wat

returned to the basin through discharges from s

systems in areas that have municipal water supp

do not have municipal sewer systems.

The withdrawal rates described above can 

compared to the flow at the gaging stations as a

cation of their relative magnitude (fig. 6); howe

these flows reflect the effects of withdrawals on 

flow. The cumulative mean monthly total withd

above the South Middleton station exceed the m

monthly streamflow at the station during July a

approach the mean monthly streamflow during 

Figure 6. Monthly mean streamflows and cumulative monthly mean withdrawals at (A) South Middleton station, (B) Ips

station, and (C) cumulative monthly mean withdrawals at Sylvania Dam, Mass., 1989–93. (Location is shown in fig. 2).

STREAMFLOW

TOTAL WITHDRAWAL

SURFACE-WATER WITHDRAWA

GROUND-WATER WITHDRAWA

STREAM DEPLETION BY

GROUND-WATER PUMPING

SUM OF STREAM DEPLETIONS 

SURFACE-WATER WITHDRAW

EXPLANATION

No withdrawal

J F MAM J J ASO

C. SYLVANIA DAM

J F MAM J J ASON D

B. IPSWICH STATION

A. SOUTH MIDDLETON STATION

0.01

0.1

1

10

100

1,000

1

10

100

1,000

0

10

20

30

40

50

60

70

FLOW, IN CUBIC FEET PER SECOND
14 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

September. The cumulative mean monthly total withdrawals above the Ipswich station approach the mean 

monthly streamflow at the station during July. Results 

of model scenarios presented later in the report will 

provide a better indication of the effects of the 

withdrawals on flows in the river.

PRECIPITATION-RUNOFF MODEL

The Hydrological Simulation ProgramFORTRAN (Bicknell and others, 1997), hereafter 

referred to as HSPF, was used to simulate runoff in 

response to precipitation and water withdrawals in the 

Ipswich River Basin. HSPF is well documented and 

can adequately represent the hydrology and complex 

water- withdrawal patterns in the basin. Computer code 

for HSPF and its companion programs are public 

domain, which can be modified when necessary to simulate unique features of individual watersheds and to 

add capabilities.

The steps followed to complete the Ipswich 

River Basin modeling study were to: (1) compile, collect, and process needed data, (2) use HSPF and associated computer software to build the model, (3) calibrate 

the model, (4) incorporate the model into GenScn 

(Kittle and others, 1998), a user-friendly decision support system, (5) examine selected water-withdrawal 

scenarios, and (6) document the model and results. 

Time series of streamflow, meteorologic, and waterwithdrawal data were needed as input to the model. 

Hydraulic and land-surface data were needed to configure the stream reaches and land surface in the basin and 

to set parameters in the model. 

Functional Description of the 

HSPF Model

HSPF is a continuous simulation model based on 

the principle of conservation of water mass, that is, 

inflow equals outflow plus or minus any change in storage. In HSPF, the land surface and the surface water 

bodies (lakes and streams) of the watershed are segmented into hydrologic response units (HRUs) and 

reaches (RCHRESs), respectively. Water budgets 

(inflows, outflows, and changes in storage) are calculated for each time step specified in the model for each 

HRU and RCHRES. 

HRUs reflect areas of relatively homogen

hydrologic response based on similar land use, 

subsurface geology, and other factors considere

important in the hydrology of the watershed. HR

divided into pervious area land segments (PERL

and impervious area land segments (IMPLNDs

RCHRESs are lengths of stream channels 

ervoirs. The downstream end of each RCHRES 

referred to as a node. Nodes are typically place

model to define channel segments with similar p

properties such as slopes and widths, at tributar

streams, at lakes and reservoirs, at data-collectio

and at other locations where estimates of stream

are desired, such as upstream and downstream f

municipal well fields, water diversions, or disch

of pollutants.

HSPF requires two primary input files fo

operation, the User Control Input (UCI) file and 

Watershed Data Management (WDM) file. The 

file directs the process actions used by the mod

sets input parameter variables. Process actions o

rithms in the model calculate the movement of 

and changes in storage. The UCI file is structur

blocks that simulate different processes. The th

main blocks of the UCI file simulate (1) PERLN

(2) IMPLNDs, and (3) RCHRESs. Within each 

are modules and sub-modules, some of which a

datory for simulations and others are optional. F

example, the PWATER modules are required to 

lated the hydrology of pervious areas, but the S

module is optional for simulating snowpack bui

and melt. A number of modules are used for ad

trative functions, such as controlling the operati

sequence of the program and directing the mod

external sources and output of time-series data. 

The WDM file contains the time-series da

to simulate streamflow or output simulation tim

results. Simulations require precipitation and ev

transpiration as input time series. Meteorologic 

series of air temperature, dew-point temperatur

radiation, and wind speed are required to calcul

snowpack buildup and melt. Output time series 

generated for any component in the simulation 

that is defined in the Time Series Catalog sectio

users manual, but time-series are mostly output 

streamflow.

Water budgets calculated on PERLNDs c

infiltration and storage in the subsurface, where

IMPLND water budgets do not. PERLND and 

IMPLND water-budget calculations include sur
Precipitation-Runoff M

runoff, but only PERLND water budget calculations 

include interflow (shallow ground-water flow that 

responds rapidly to precipitation), baseflow (deep 

ground-water flow that remains relatively constant), 

and optionally a deep ground-water flow component 

that discharges outside of the basin. Process actions 

that control the rate of infiltration and change in 

subsurface storage make simulation of PERLNDs 

considerably more complex than the water-budget 

calculations for IMPLNDs. A complete description of 

the process actions and input model parameters are 

given in the ‘HSPF Users Manual’ (Bicknell and 

others, 1997).

Precipitation is the principal inflow to a watershed; however, inflows can also include septic effluents 

and other sources. Precipitation and other sources of 

moisture supply on impervious and pervious areas can 

be retained at or above the surface as interception storage and as snowpack storage, but only pervious areas 

retain water in the soil matrix. HSPF considers soilwater storage in two-zones: (1) the upper-zone storage, 

generally considered the upper-soil horizon, and (2) the 

lower-zone storage, a deep-soil zone that only allows 

outward movement of water through evapotranspiration by deep-rooted vegetation. Stream channels and 

lakes also have a storage component defined by their 

geometry.

Precipitation that is not held in storage or is lost 

to evapotranspiration (or optionally exits through deep 

ground-water) is discharged to RCHRESs as surface 

runoff from IMPLNDs and PERLNDs and as subsurface outflows from PERLNDs. The area of IMPLND 

and PERLND that drains to a RCHRES and the linkage 

of one RCHRES to another are specified in the 

SCHEMATIC block and associated MASSLINK block 

or NETWORK block, or both. The schematic or network blocks are used to represent the physical layout of 

the watershed. Relations among stage, storage, surface 

area, and discharge are specified for each reach in usersupplied function tables (FTABLEs). Primary inflows 

to a reach are (1) surface runoff from PERLNDs and 

IMPLNDs, (2) interflow and base flow from 

PERLNDs, and (3) inflow from other reaches. Inflow 

as direct precipitation and outflow as evapotranspiration, or inflows and outflows from other sources, such 

as wastewater effluent or water withdrawals, also can 

be simulated for RCHRESs when specified by the user.

The inflows to and outflows from a stream reach 

are illustrated in figure 7. Surface runoff enters the 

reach from impervious surfaces (SURI) and pervious 

surfaces (SURO). Infiltrated precipitation can fl

the reach as shallow quick responding interflow 

(IFWO) or a slow responding active ground wa

(base flow) component (AGWO). Inflow can al

from upstream reaches (IVOL). Two outflow ex

gates) are illustrated (a reach can have up to 5 e

The first gate (OVOL 1) is the volume time-seri

water withdrawals (OUTDGT 1) for each reach 

by the EXTERNAL-SOURCE block. Specifyin

first outflow gate for water withdrawals require

these withdrawals be satisfied before water is ro

through successive outflow gates. In the Ipswic

Basin model, water usually is routed downstrea

through the second outflow gate (OVOL 2), as i

trated, but in some instances a third outflow gat

used to route water downstream as described la

the report.

Data Base

Time-series data required for simulations 

time series generated by the model are stored in 

Watershed Data Management (WDM) file. The 

data base is accessed by ANNIE, an interactive 

interface to store, manage, display, transform, p

analyze time-series data (Flynn and others, 1995

GenScn, a graphical user interface that has man

features of ANNIE but improves the ability to g

and analyze model scenarios and compare mod

results (Kittle and others, 1998). Data in variou

mats are entered into the WDM data base by us

IOWDM program (Lumb and others, 1990).

The WDM data base is organized by data 

with a unique data set number (DSN) assigned 

rate time series. Each data set also has attribute

describe the data type, time step, location, and o

important features. In the Ipswich WDM file, th

100 DSNs are used for input meteorologic time

and observed streamflow. Data sets with numbe

larger than 100 are generally organized by reac

Table 2 describes the general organization of the 

file.

The sum of individual ground-water with

plus any surface-water withdrawals provides th

water withdrawal time series for each reach (OU

1 in fig. 7). These time series were entered into 

WDM file in data set numbers 101 to 166 wher

last two digits correspond to the reach number. 

GenScn, these time series are identified as ExD
16 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

IFWO

AGWO

RCHRES

Outflow to pumping well 

or surface withdrawal,

or both (OVOL 1) Outflow to 

downstream

reach (OVOL 2)

Inflow from 

upstream reach 

(IVOL)

pervious areas (PERLND's)

SURO - Surface runoff

IFWO - Interflow

AGWO - Active ground-water flow

Pumping

Well

SURI

SURO

Flow from impervious 

areas (IMPLND's)

SURI - surface runoff

Flow Components from

Evaporation

Precipitation

Evapotranspiration

Precipitation

in the Constituent window, OBSERVED in the 

Scenario window, and have a location identified with 

the appropriate RCHRES segment. 

Streamflow depletions resulting from groundwater withdrawals were determined for wells in the 

basin by use of the STRMDEPL program, which is 

documented in Appendix A. Time series of streamflow 

depletions by individual wells and surface-water 

withdrawals are stored in the WDM file in data sets 

1010 to 1679; the second and third digits correspond to 

the reach number and the last digit corresponds to an 

individual well. This scheme allows identification of up 

to 10 wells along a reach. In the Ipswich Basin HSPF 

model, only reach 8 had more than 10 wells simulated; 

therefore, the 11th well was numbered with the successive reach number (1090) because no withdrawals were 

simulated in this reach. In GenScn, the Constituent 

window identifies streamflow depletions by individual 

wells by DEPL and surface-water withdrawals by 

SWDL. Actual well-pumping rates are stored in 

WDM file in data sets 2010 to 2679 using the s

numbering scheme described above for the indi

depletions. The actual pumping rates are identifi

the GenScn Constituent window by PUMP. All 

drawals and streamflow depletions are identifie

GenScn Scenario window by OBSERVED.

Streamflow Data

Observed daily-flow data were obtained f

USGS gaging stations at South Middleton (193

through 1995) and Ipswich (1931 through 1995)

These stations provided the primary data used t

brate the model. Records from the South Middl

station are generally rated fair (85 percent of th

discharge are within 15 percent of the true disch

and those from the Ipswich station are generally 

good (within 10 percent of the true discharge) f

Figure 7. Schematic of inflows to and outflows from a stream reach (RCHRES) in the Hydrological Simulation 

Program-FORTRAN (HSPF).
Precipitation-Runoff M

1989 to 1993 water years (Socolow and others, 1989–

93). Streamflows for the South Middleton station are in 

DSN 19 and those for the Ipswich station are in DSN 

56 in the WDM file; these DSNs correspond to the 

reach numbers in the model (fig. 8) in which these 

stations are located.

Meteorologic Data

Meteorologic data, including precipitation, air 

temperature, dew-point temperature, solar radiation, 

and wind speed for the Ipswich River Basin were provided by the Marine Biological Laboratory (MBL) in 

Woods Hole, Mass. These data are in hourly time steps 

and span the period January 1, 1961 through December 

31, 1995. Hourly precipitation records were also provided by Robert Lautzenheiser (retired state climatologist, written commun., 1998) for Reading, Mass., for 

the period January 1, 1983 to December 31, 1998.

The MBL selected 30 National Weather Service 

(NWS) weather stations in and around the Ipswich 

River Basin to develop their data base (fig. 1). Some of 

the stations used are a substantial distance (as m

45 mi) from the basin because only NWS first-o

stations collect data other than precipitation and 

extreme air temperature, and those stations are s

distributed. Table 3 lists the stations used to dev

the MBL data base, the types of data collected, 

locations, and periods of record.

The MBL provided meteorologic data in 

tial grid of the Ipswich River Basin that was po

by a weighted linear spatial interpolation of hou

daily values from the individual stations into ea

cell (Luc Claessens, Marine Biological Laborat

1999, written commun.). All hourly meteorolog

was in a grid matrix of 4- by 3-cells that are 38.6 

area. Hourly precipitation and air temperature t

series were developed from 9 stations with hou

and 26 stations with daily data during 1961 to 1

The hourly precipitation data for Reading suppl

Robert Lautzenheiser were included in the MBL 

base. The hourly stations were used as a basis f

mating hourly values for stations where only da

values were available using METCMP (Lumb a

Kittle, 1995). The hourly values at each station 

then spatially interpolated to obtain hourly valu

the 12 grid cells.

Dew-point temperature, air temperature, 

radiation, and wind speed were obtained from t

first-order NWS stations listed in table 3. Solar 

tion was unavailable for 1991 through 1995 at t

stations and was estimated from cloud cover by 

a method reported by Morton and others (1985)

The daily and hourly values of the meteo

variables obtained from the MBL grids were av

to obtain a single value for each variable and tim

for the basin. The basin-wide average was comp

because use of the grid data would have require

complete set of pervious (PERLND) and imper

(IMPLND) land units developed for the model 

duplicated in the UCI file for each grid cell. Inc

of the additional land units would have increase

mendously the size and complexity of the UCI 

slowed processing time. The basin-wide average 

were considered to be adequate for running the 

because the annual spatial variation among the 

was small. Mean annual precipitation varied by 

cent or less among the cells in the basin. This is 

ered a small variation in comparison to the larg

sampling errors associated with precipitation da

All other meteorological variables varied less th

precipitation.

Table 2. Organization and description of Data Set Numbers 

(DSNs) in the Watershed Data Management (WDM) system 

for the Ipswich River Basin, Mass.

[STRMDEPL, stream depletion by ground-water withdrawals; HSPEXP, 

Hydrological Simulation Program Expert System].

DSN Purpose

1 – 100 Observed data

101 – 167 Input total water withdrawals for a reach input to 

the model (OUTDGT 1)

200 – 267 Output of simulated streamflow for a reach

301 – 367 Output of total water withdrawals satisfied by 

streamflow for a reach

1010 – 1679 Individual surface-water withdrawal or stream 

depletion from ground-water withdrawal 

computed by STRMDEPL, where

101x – 167x corresponds to reach number and

1xx0 – 1xx9 corresponds to individual withdrawal point 

(maximum 10 per reach)

2010 – 2679 Actual withdrawals for individual wells, where

201x – 267x corresponds to reach number and

2xx0 – 2xx9 corresponds to individual withdrawal point 

(maximum 10 per reach)

5000 – 5100 Simulated flow components for HSPEXP

6000 – Simulation results from different scenarios, 

where

60xx – 6xxx second digit corresponds to a unique scenario 

and

6x01 – 6x67 last two digits corresponds to reach number
18 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

HAMILTON DANVERS PEABODY LYNNFIELD WOBURN BURLINGTON TEWKSBURY ANDOVER WILMINGTON NORTH ANDOVER BOXFORD MIDDLETON NORTH READING READING TOPSFIELD ROWLEY IPSWICH WENHAMBEVERLY SALEM LYNN ESSEX

BILLERICA

MANCHESTER

GLOUCESTER

WAKEFIELD

GEORGETOWN

ATLANTIC OCEAN

01102000

01101500

01101740

To BeverlySupply

To Salem

Supply

To DanversSupply

To Danversand MiddletonSupply

To PeabodySupply

To Spring PondReservoirPeabody Supply

To LynnSupply

To BurlingtonSupply

PutnamvilleReservoir Swan

Pond

EmersonBrookReservoir

WinonaPond

SuntaugLake

Wenham

Lake Longham

Reservoir Middleton

Pond

Lowell Pond

Cleveland Brook

Salem-Beverly Canal

Pye Brook

Howlett Brook

Ni chols Brook

Fish Brook

Lubber s Brook

Ipswich

R vi

er

Black Brook

Miles River

Idlewild Brook

Emerson Brook

Boston Brook

Wills Brook

N orris Brook

River

Bear Meadow Brook

Martins Brook

a M

odae Mel p

w r B oo k

Mil Bl koor

Ip

ws ich

9

3

1

8

5

38

32

12

6

51

7

39

58

30

65

36

61

2

53

13

49

52

31

11

42

40

50

64

14

20

66

33

41

46

15

48

62

54

34

4

28

35

16

23

27

29

55

67

59

18

24

60

10

26

45

57

25

21

37

44

63

22

17

19

43

42o30'

71o10'

42o

40'

70o50' 

0 2 4 6 MILES

EXPLANATION

01101740

15

01101500

PARTIAL RECORD  STREAM-GAGING STATION AND NUMBERSURFACE-WATER  TRANSFER

—Arrows

 leading outside the basin  indicates transfer of water  from the basinSURFACE-WATER  WITHDRAWALGROUND-WATER 

OPEN WATER

REACH AND MODEL NUMBER

—Subbasin

 boundary show

BASIN BOUNDARY

SUBBASIN BOUNDARY  TO GAGING STATION

SUBBASIN BOUNDARY

TOWN BOUNDARY

STREAM-GAGING 

ATLANTIC

OCEAN
Precipitation-Runoff Model 19

NWS

Station

No.

Station name Latitude Longitude

Precipitation Temperature Solar

radiation

Wind

speed

Cloud

cover

Period of record

Hourly Daily Minimum

MaximumDewpoint Start End

190535 Bedford, Mass. 42° 29′ 00′′ 71° 17′ 00′′ ● ●● 1/01/61 12/31/95

190770 Boston, Mass.–Logan Airport 42° 22′ 00′′ 71° 02′ 00′′ ● ●● 1/01/61 12/31/95

14739 Boston, Mass.–Logan Airport 42° 22′ 00′′ 71° 02′ 00′′ ● ●●●● 1/01/61 12/31/95

191447 Chestnut Hill, Mass. 42° 20′ 00′′ 71° 09′ 00′′ ● ●● 1/01/61 4/30/86

191992 Dracut, Mass. 42° 42′ 00′′ 71° 17′ 00′′ ● ●● 1/01/71 6/15/78

193276 Groveland, Mass. 42° 45′ 00′′ 71° 03′ 00′′ ● ●● 9/01/92 12/31/95

193276 Groveland, Mass. 42° 45′ 00′′ 71° 03′ 00′′ ● 9/01/92 12/31/95

193505 Haverhill, Mass. 42° 46′ 00′′ 71° 04′ 00′′ ● ●● 1/01/61 12/31/95

193876 Ipswich, Mass. 42° 40′ 00′′ 70° 52′ 00′′ ● 1/01/61 12/31/95

194105 Lawrence, Mass. 42° 42′ 00′′ 71° 10′ 00′′ ● ●● 1/01/61 12/31/95

194313 Lowell, Mass. 42° 39′ 00′′ 71° 22′ 00′′ ● ●● 1/01/61 12/31/95

194502 Marblehead, Mass. 42° 30′ 00′′ 70° 52′ 00′′ ● ●● 9/01/84 12/31/95

194502 Marblehead, Mass. 42° 30′ 00′′ 70° 52′ 00′′ ● 9/01/84 12/31/95

194744 Middleton, Mass. 42° 36′ 00′′ 71° 01′ 00′′ ● ●● 1/01/61 12/31/95

195175 Natick, Mass. 42° 18′ 00′′ 71° 22′ 00′′ ● ●● 4/01/78 12/31/95

195285 Newburyport, Mass. 3 WNW 42° 50′ 00′′ 70° 56′ 00′′ ● 1/01/61 12/31/95

196245 Peabody, Mass. 42° 32′ 00′′ 70° 59′ 00′′ ● ●● 1/01/67 12/31/95

196783 Reading, Mass. 42° 31′ 00′′ 71° 08′ 00′′ ● ●● 1/01/61 12/31/95

196783 Reading, Mass. 42° 31′ 00′′ 71° 08′ 00′′ ● 12/01/80 12/31/95

196977 Rockport, Mass. 1 ESE 42° 39′ 00′′ 70° 36′ 00′′ ● ●● 1/01/61 1/16/83

196977 Rockport, Mass. 1 ESE 42° 39′ 00′′ 70° 36′ 00′′ ● 1/01/61 12/31/83

197124 Salem, Mass.–Coast Guard Station 42° 32′ 00′′ 70° 52′ 00′′ ● ●● 1/01/61 12/31/66

198030 Spot Pond, Mass. 42° 27′ 00′′ 71° 05′ 00′′ ● 1/01/61 7/31/77

199360 Weston, Mass. 42° 23′ 00′′ 71° 19′ 00′′ ● ●● 1/01/61 6/30/68

94746 Worcester, Mass Municipal Airport 42° 16 00′′ 71° 52′ 00′′ ●●● 1/01/61 12/31/95
ecipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massachusetts

14745 Concord, N.H. Municipal Airport 43° 12′ 00′′ 71° 31′ 00′′ ●●● 1/01/61 12/31/95

14745 Concord, N.H. Municipal Airport 43° 12′ 00′′ 71° 31′ 00′′ ● 1/01/95 12/31/95

272174 Durham, N.H. 43° 09′ 00′′ 70° 57′ 00′′ ● 1/01/61 12/31/95

272800 Epping, N.H. 43° 02′ 00′′ 70° 05′ 00′′ ● ●● 12/01/63 12/31/95

273626 Greenland, N.H. 43° 01′ 00′′ 70° 50′ 00′′ ● ●● 8/01/73 12/31/95

274234 Hudson, N.H. 42° 47′ 00′′ 71° 26′ 00′′ ● 1/01/61 12/31/72

275072 Manchester, N.H. 43° 00′ 00′′ 71° 29′ 00′′ ● ●● 1/01/61 9/30/72

275211 Massabesic Lake, N.H. 42° 59′ 00′′ 71° 24′ 00′′ ● ●● 1/01/61 12/31/95

275705 Nashua, N.H. 2 42° 47′ 00′′ 71° 30′ 00′′ ● 12/01/72 2/28/85

275712 Nashua, N.H. 2 NNW 42° 47′ 00′′ 71° 29′ 00′′ ● ●● 1/01/61 12/31/95

275712 Nashua, N.H. 2 NNW 42° 47′ 00′′ 71° 29′ 00′′ ● 2/01/85 12/31/95

276980 Portsmouth, N.H. 43° 04′ 00′′ 70° 43′ 00′′ ● ●● 1/01/61 5/31/73

279740 Windham, N.H. 3 NW 42° 49′ 00′′ 71° 20′ 00′′ ● ●● 1/01/61 7/31/76

NWS

Station

No.

Station name Latitude Longitude

Precipitation Temperature Solar

radiation

Wind

speed

Cloud

cover

Period of record

Hourly Daily Minimum

MaximumDewpoint Start End
Precipitation-Runoff M

Potential evapotranspiration (PET) was calculated from daily high and low temperatures, and solar 

radiation by the Jensen-Haise (1963) method using 

METCMP (Lumb and Kittle, 1995). Near-final 

calibration results indicated a seasonal bias that can 

be attributed to the use of a constant monthly variable 

coefficient (CTS) in the Jensen-Haise computation. 

PET estimates were subsequently recalculated with a 

variable CTS value to correct for seasonal bias. Methods that were used to develop the CTS value are 

explained in the model-calibration section of the report.

Water-Withdrawal Data

Water-withdrawal information was obtained by 

questionnaire from water suppliers for 18 of the 22 

towns in the Ipswich River Basin or obtaining water 

from the basin. Water suppliers were asked to provide 

information on their drinking-water and waste-water 

infrastructure and time series of withdrawal rates and 

waste-water discharges for the period beginning 

January 1, 1989, through the most-recently available 

data. Information was not requested from the towns of 

Woburn, Billerica, Rowley and Georgetown because 

their areas within the basin are small and they do not 

have municipal water supplies or their municipal water 

supply comes from an adjacent basin. 

The information provided by each town differed 

considerably, and thus required various degrees of 

processing to format the data for input to the model.

Table 4 summarizes water-use information obtained 

from the towns. Water-use data for Hamilton, North 

Reading, Peabody, and Topsfield were obtained from 

monthly water-use records reported to the MADEP. In 

addition, the MADEP provided monthly time series for 

seven private water users in the basin. All other wateruse information was obtained directly from the water 

suppliers. In some instances, copies of hand-written log 

books provided by the water suppliers indicated periods when water meters were not in service. Recorded 

withdrawals for adjacent time periods were used to 

estimate withdrawals for the missing periods. This 

could result in small differences between the withdrawals reported to MADEP and the withdrawals 

used in the model.

Table 5 summarizes the 96 registered or permitted public and commercial water withdrawals in the 

basin. Several towns have large areas served by municipal water supplies, but with no municipal wastewater 

systems. These areas rely on onsite septic systems for 

waste treatment. Discussion of how these areas 

treated in the model is provided in the section o

‘Hydrologic Response Units.’ The municipal wa

data and methods used to process them are desc

below (locations of the areas described, river re

numbers and withdrawal locations are shown in 

Generally, the town water-use data are presente

order of downstream reach number (as listed in 

table 5), but some towns have been grouped bec

similarities in water-use patterns and methods u

process the data.

Burlington. The town of Burlington has 

age reservoir at the headwaters of Maple Meado

Brook. Water is pumped to the reservoir from o

the Ipswich Basin, stored, and released for later 

outside the basin; therefore, the surface area of 

ervoir was not included in the model. Water fro

land area that would normally drain to the reser

piped under the reservoir and contributes to Ma

Meadow Brook. Within the basin, the town is se

municipal water and sewer, which is discharged 

the basin. 

Wilmington. The town of Wilmington ob

water from 5 wells adjacent to Maple Meadow 

2 wells adjacent to Lubbers Brook, and 3 wells 

cent to Martins Brook. One of the wells was no

pumped during the calibration period, but was in

in the model with no withdrawals specified. The 

provided combined total monthly withdrawal ra

1969 through part of 1997 and average annual w

drawal rates for individual wells from 1991–96

of the individual average annual well withdraw

the total average annual withdrawals for the 199

period were used to apportion the total monthly 

drawals to individual well withdrawals for the 1

period. The daily withdrawals were obtained by 

gregating monthly withdrawals using Wenham 

as described below. The combined average with

from these wells during the calibration period w

2.53 Mgal/d. Wilmington is partially served by 

sewer.

Hamilton, Reading, North Reading, an

Topsfield. These towns rely solely on ground w

their water supplies except North Reading, whi

imports up to 1.5 Mgal/d of additional water du

summers from the Merrimack River Basin. Sev

vate surface-water withdrawals from within the

municipalities were also included in the model. 
22 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Table 4. Summary of municipal water-use information in the Ipswich River Basin, Mass.

[-- indicates not applicable]

Municipality

Water supply Wastewater Source

data

time step

Data in model

Remarks Public

system

Source

in basin

Public

system

Discharge

in basin

Begin

year

End

year

Andover Yes No Yes No -- -- -- No withdrawals from or returns to the bas

Beverly Yes Yes Yes No Daily 1989 1998 Waste discharged to South Essex Sewage

Treatment Plant

Billerica Yes No Yes No -- -- -- No withdrawals from or returns to the bas

Boxford No -- No -- -- -- -- No public supply or sewer system

Burlington Yes No Yes No -- -- -- No withdrawals from or returns to the bas

Danvers Yes Yes Yes No Monthly 1987 1997 Waste discharged to South Essex Sewage

Treatment Plant

Georgetown Yes No No -- -- -- -- No withdrawals from or returns to the bas

Hamilton Yes Yes No Yes Monthly 1989 1993 Waste all goes to septic systems

Ipswich Yes Yes Yes No Daily 1989 1998 Ipswich wastewater is discharged to the Ip

River below Sylvania Dam. About 50 p

the population is unsewered.

Lynn Yes Yes Yes No Daily 1989 1997 No land area in basin; waste discharged to 

Wastewater Treatment Plant

Lynnfield Yes Yes No Yes Daily 1989 1998 Waste all goes to septic systems

Middleton Partial Yes No Yes Monthly 1987 1997 About 60 percent of the population has pu

water; waste all goes to septic systems

North 

Andover

Yes No Yes No -- -- -- No withdrawals from or returns to the bas

North 

Reading

Yes Yes No Yes Monthly 1989 1993 Waste all goes to septic systems

Peabody Yes Yes Yes No Monthly 1989 1993 Waste discharged to South Essex Sewage

Treatment Plant

Reading Yes Yes Yes No Monthly 1987 1997 Waste discharged to Mass. Water Resourc

Authority

Rowley Yes No No -- -- -- -- No withdrawals from or returns to the bas

Salem Yes Yes Yes No Daily 1989 1998 No land area in basin; waste discharged to 

Essex Sewage-Treatment Plant

Tewksbury Yes No Yes No -- -- -- No withdrawals from or returns to the bas

Topsfield Yes Yes No Yes Monthly 1989 1993 Waste all goes to septic systems

Wenham Yes Yes No Yes Daily 1989 1998 Waste all goes to septic systems

Wilmington Yes Yes Partial Partial Daily 1989 1998 Wastewater from 16 percent of population 

Mass. Water Resources Authority

Woburn Yes No No -- -- -- -- No withdrawals from or returns to the bas
Precipitation-Runoff Model 23

Reach

No.

WDM

data

set 

No.

Mass. DEP

source 

No.

Source name Water supplier name

Included 

in 

model

Latitude Longitude Town

Distance 

from 

stream

(feet)

1 -- 3048000-02S Mill Pond Reservoir intake Burlington Water Dept. No 42° 30′ 54′′ 71° 10′ 18′′ Burlington --

1 1012 3342000-03G Chestnut Street well Wilmington Water Dept. Yes 42° 31′ 48′′ 71° 10′ 08′′ Wilmington 560

1 1013 3342000-04G Town Park well Wilmington Water Dept. Yes 42° 32′ 05′′ 71° 09′ 39′′ Wilmington 560

1 1014 3342000-07G Butters Row well 1 Wilmington Water Dept. Yes 42° 31′ 58′′ 71° 09′ 58′′ Wilmington 490

1 1015 3342000-09G Butters Row well 2 Wilmington Water Dept. Yes 42° 32′ 02′′ 71° 09′ 59′′ Wilmington 280

1 1016 3342000-10G Chestnut Street well 1A Wilmington Water Dept. Yes 42° 31′ 48′′ 71° 10′ 09′′ Wilmington 560

1 -- 3342001-01G Millbrook well 1 Millbrook Country Day School, Inc. No 42° 31′ 43′′ 71° 10′ 48′′ Wilmington --

5 1051 3342000-05G Shawsheen Avenue well Wilmington Water Dept. Yes 42° 33′ 30′′ 71° 11′ 29′′ Wilmington 120

5 1052 3342000-06G Aldrich Road well Wilmington Water Dept. Yes 42° 33′ 01′′ 71° 12′ 30′′ Wilmington 420

8 1080 3213000-06G Stickney well North Reading Water Dept. Yes 42° 33′ 50′′ 71° 08′ 01′′ North Reading 3,300

8 1081 3246000-02G Revay well 2 Reading Water Dept. Yes 42° 32′ 14′′ 71° 07′ 39′′ Reading 5,980

8 1081 3246000-03G Revay well 1 Reading Water Dept. Yes 42° 32′ 16′′ 71° 07′ 37′′ Reading --

8 1082 3246000-04G Well 2 Reading Water Dept. Yes 42° 32′ 58′′ 71° 07′ 60′′ Reading 1,340

8 1083 3246000-05G Well 3 Reading Water Dept. Yes 42° 32′ 56′′ 71° 07′ 59′′ Reading 1,250

8 1084 3246000-06G Bline well Reading Water Dept. Yes 42° 33′ 06′′ 71° 07′ 54′′ Reading 490

8 1085 3246000-07G Town Forest well Reading Water Dept. Yes 42° 33′ 14′′ 71° 07′ 38′′ Reading 140

8 1086 3246000-08G Well 82 20 Reading Water Dept. Yes 42° 33′ 11′′ 71° 07′ 48′′ Reading 140

8 1087 3246000-09G Well 66 8 Reading Water Dept. Yes 42° 33′ 05′′ 71° 08′ 02′′ Reading 490

8 1088 3246000-10G Well 13 Reading Water Dept. Yes 42° 32′ 59′′ 71° 08′ 11′′ Reading 1,110

8 1089 3246000-11G Well 15 Reading Water Dept. Yes 42° 32′ 56′′ 71° 08′ 10′′ Reading 970

8 1091 31724602-01G Well 1 Meadow Brook Golf Club Yes 42° 32′ 34′′ 71° 07′ 44′′ Reading 550

8 1092 31724602-01S Surface-water withdrawal 1 Meadow Brook Golf Club Yes 42° 32′ 32′′ 71° 07′ 51′′ Reading --

12 -- 3009003-01G Harold Parker well Harold Parker State Forest No 42° 36′ 35′′ 71° 05′ 31′′ Andover --

12 -- 3009004-01G Camp Evergreen well Camp Evergreen No 42° 36′ 20′′ 71° 05′ 23′′ Andover --

12 1125 3213000-04G Central Street wellfield North Reading Water Dept. Yes 42° 35′ 56′′ 71° 06′ 44′′ North Reading 100

 means not included or not applicable]
ecipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massachusetts

12 1126 3213000-05G Route 125 well North Reading Water Dept. Yes 42° 35′ 58′′ 71° 08′ 06′′ North Reading 1,550

12 1127 3213000-02G Lakeside Boulevard well 2 North Reading Water Dept. Yes 42° 35′ 46′′ 71° 07′ 51′′ North Reading 140

12 1127 3213000-03G Lakeside Boulevard well 3 North Reading Water Dept. Yes 42° 35′ 48′′ 71° 07′ 50′′ North Reading 140

12 1127 3213000-07G Lakeside Boulevard well 4 North Reading Water Dept. Yes 42° 35′ 48′′ 71° 07′ 50′′ North Reading 140

12 1128 3342000-01G Browns Crossing well Wilmington Water Dept. Yes 42° 34′ 56′′ 71° 08′ 44′′ Wilmington 150

13 1131 3213000-01G Railroad bed tubular wells North Reading Water Dept. Yes 42° 34′ 42′′ 71° 07′ 52′′ North Reading 140

13 1132 3342000-02G Barrows wellfield Wilmington Water Dept. Yes 42° 34′ 20′′ 71° 08′ 35′′ Wilmington 100

13 1133 3342000-08G Salem Street well Wilmington Water Dept. Yes 42° 34′ 42′′ 71° 07′ 60′′ Wilmington 150

17 1171 3164000-02G Main Street well Lynnfield Center Water District Yes 42° 33′ 24′′ 71° 02′ 41′′ Lynnfield 1,060

17 1172 3164000-05G Glen Drive well 1 Lynnfield Center Water District Yes 42° 33′ 33′′ 71° 02′ 58′′ Lynnfield 1,650

17 1173 3164000-06G Glen Drive well 2 Lynnfield Center Water District Yes 42° 33′ 33′′ 71° 02′ 58′′ Lynnfield 1,650

17 1174 3164000-07G Glen Drive well 3 Lynnfield Center Water District Yes 42° 33′ 33′′ 71° 02′ 58′′ Lynnfield 1,650

17 1175 3164000-08G Glen Drive well 4 Lynnfield Center Water District Yes 42° 33′ 33′′ 71° 02′ 58′′ Lynnfield 1,650

17 1176 31716402-01G Well 1 - Clubhouse Sagamore Springs Golf Club, Inc. Yes 42° 33′ 26′′ 71° 02′ 18′′ Lynnfield 350

17 1177 31716402-02G Well 2 - Maintenance Sagamore Springs Golf Club, Inc. Yes 42° 33′ 39′′ 71° 02′ 29′′ Lynnfield 350

17 1178 31716402-03G Well 3 - Residence Sagamore Springs Golf Club, Inc. Yes 42° 33′ 32′′ 71° 02′ 30′′ Lynnfield 100

17 1179 31716402-01S Surface-water withdrawal 1 Sagamore Springs Golf Club, Inc. Yes 42° 33′ 30′′ 71° 02′ 28′′ Lynnfield --

17 1170 31716402-02S Surface-water withdrawal 2 Sagamore Springs Golf Club, Inc. Yes 42° 33′ 30′′ 71° 02′ 28′′ Lynnfield --

17 -- 3164005-01G Pocahontas well Pocahontas Spring Water No 42° 33′ 11′′ 71° 02′ 20′′ Lynnfield

18 1181 3163000-05S Ipswich River Lynn Water and Sewer Commission Yes 42° 34′ 17′′ 71° 02′ 57′′ Lynn --

18 1182 31721303-01S Surface-water withdrawal 1 Thomson Country Club Yes 42° 34′ 16′′ 71° 02′ 09′′ North Reading --

18 1183 31721303-02S Surface-water withdrawal 2 Thomson Country Club Yes 42° 34′ 16′′ 71° 02′ 09′′ North Reading --

20 -- 3184007-01G Legion Post well American Legion Post 227 No 42° 34′ 12′′ 71° 00′ 37′′ Middleton --

20 1201 3229000-03S Ipswich River Peabody Water Dept. Yes 42° 33′ 39′′ 71° 00′ 16′′ Peabody --

21 -- 3229000-02S Suntaug Lake Peabody Water Dept. No 42° 31′ 17′′ 70° 59′ 54′′ Peabody --

22 -- 3229000-04S Winona Pond Reservoir Peabody Water Dept. No 42° 32′ 09′′ 71° 00′ 46′′ Peabody --

23 1231 3229000-01G Pine Street well Peabody Water Dept. Yes 42° 32′ 38′′ 71° 00′ 02′′ Peabody 800

23 1232 3229000-02G Johnson Street well Peabody Water Dept. Yes 42° 32′ 43′′ 70° 59′ 57′′ Peabody 100

25 1251 3071000-01G Well 1 Danvers Water Dept. Yes 42° 34′ 29′′ 70° 59′ 40′′ Middleton 100

25 1252 3071000-02G Well 2 Danvers Water Dept. Yes 42° 34′ 08′′ 70° 59′ 48′′ Middleton 100

Reach

No.

WDM

data

set 

No.

Mass. DEP

source 

No.

Source name Water supplier name

Included 

in 

model

Latitude Longitude Town

Distance 

from 

stream

(feet)
Precipitation-Runoff Model 25

25 -- 3184004-01G Middleton Golf Course well Middleton Golf Course, Inc. No 42° 35′ 12′′ 71° 00′ 46′′ Middleton --

26 1261 3071000-01S Middleton Pond Reservoir Danvers Water Dept. Yes 42° 35′ 41′′ 71° 01′ 15′′ Middleton --

28 -- 3071002-01P Danvers Water Dept. Danvers State Hospital No 42° 34′ 58′′ 70° 58′ 28′′ Danvers --

30 1301 3071000-02S Swan Pond Reservoir Danvers Water Dept. Yes 42° 35′ 19′′ 71° 02′ 50′′ Middleton --

30 1302 3071000-03S Emerson Brook Reservoir Danvers Water Dept. Yes 42° 36′ 12′′ 71° 02′ 04′′ Middleton --

30 -- 3184011-01G Candlelite well Candlelite Motor Inn No 42° 37′ 21′′ 71° 03′ 05′′ Middleton --

36 1361 -- Surface-water withdrawal 1 Tara Country Club Yes 42° 36′ 10′′ 70° 58′ 24′′ Danvers --

39 -- 3038009-01G Cole School well Harry Lee Cole School No 42° 39′ 37′′ 71° 00′ 10′′ Boxford --

39 -- 3038011-01G First Church Rock well First Church Congregation No 42° 39′ 52′′ 70° 59′ 58′′ Boxford --

39 -- 3038013-01G Boxford Community Store well Boxford Community Store, Inc. No 42° 39′ 45′′ 70° 59′ 55′′ Boxford --

40 -- 3038020-01G Well 1 Andrews Farm Water Co., Inc. No 42° 38′ 36′′ 70° 58′ 31′′ Boxford --

44 1441 3030001-04S Ipswich River to Wenham Lake Salem Beverly Water Supply Board Yes 42° 36′ 24′′ 70° 54′ 05′′ Wenham --

44 1442 3030001-04S Ipswich River to Putnamville Reservoir Salem Beverly Water Supply Board Yes 42° 36′ 24′′ 70° 54′ 05′′ Wenham --

45 1451 3030001-03S Putnamville Reservoir to Wenham Lake Salem Beverly Water Supply Board Yes 42° 36′ 08′′ 70° 56′ 24′′ Danvers --

46 -- 3298002-01G Sleepy Hollow well Eagle Tor Trust No 42° 36′ 51′′ 70° 56′ 22′′ Topsfield --

49 1491 3119000-04G Caisson well Hamilton Water Dept. Yes 42° 37′ 06′′ 70° 53′ 50′′ Hamilton 100

49 1492 3119000-05G Idlewild 1 well Hamilton Water Dept. Yes 42° 37′ 12′′ 70° 53′ 50′′ Hamilton 300

49 1493 3119000-06G Idlewild 2 well Hamilton Water Dept. Yes 42° 37′ 13′′ 70° 53′ 45′′ Hamilton 720

49 1494 3320000-01G Well 1 Wenham Water Dept. Yes 42° 36′ 37′′ 70° 53′ 40′′ Wenham 400

49 1495 3320000-02G Well 2 Wenham Water Dept. Yes 42° 36′ 39′′ 70° 53′ 41′′ Wenham 300

50 1501 3119000-03G Patton well Hamilton Water Dept. Yes 42° 38′ 01′′ 70° 54′ 04′′ Hamilton 920

50 1502 3298000-02G Perkins Row well Topsfield Water Dept. Yes 42° 38′ 50′′ 70° 55′ 33′′ Topsfield 300

51 -- 3038001-01G Well 1 Four Mile Village No 42° 41′ 07′′ 71° 00′ 13′′ Boxford --

51 -- 3038001-02G Well 2 Four Mile Village No 42° 41′ 07′′ 71° 00′ 14′′ Boxford --

51 -- 3038001-03G Bedrock well 3 Four Mile Village No 42° 41′ 07′′ 71° 00′ 08′′ Boxford --

53 1531 3298000-01G North Street well Topsfield Water Dept. Yes 42° 39′ 12′′ 70° 56′ 34′′ Topsfield 100

53 -- 3298005-01G Well 1 New Meadows Golf Club No 42° 39′ 50′′ 70 °55′ 34′′ Topsfield --

57 1571 3144000-04G Winthrop well 2 Ipswich Water Dept. Yes 42° 39′ 26′′ 70° 53′ 07′′ Ipswich 250

57 1571 3144000-05G Winthrop well 3 Ipswich Water Dept. Yes 42° 39′ 26′′ 70° 53′ 05′′ Ipswich 380

59 1591 3144000-03G Winthrop well 1 and tubular wells Ipswich Water Dept. Yes 42° 39′ 20′′ 70° 52′ 38′′ Ipswich 70

Reach

No.

WDM

data

set 

No.

Mass. DEP

source 

No.

Source name Water supplier name

Included 

in 

model

Latitude Longitude Town

Distance 

from 

stream

(feet)
ecipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massachusetts

61 1611 3030001-02S Longham Reservoir to Wenham Lake Salem Beverly Water Supply Board Yes 42° 35′ 27′′ 70° 52′ 17′′ Wenham --

61 1612 3030001-02S Longham Reservoir to Miles River Salem Beverly Water Supply Board Yes 42° 35′ 27′′ 70 °52′ 17′′ Wenham --

62 1621 3030001-01S Wenham Lake to Beverly Salem Beverly Water Supply Board Yes 42° 35′ 03′′ 70° 53′16′′ Beverly/Wenham --

62 1622 3030001-01S Wenham Lake to Salem Salem Beverly Water Supply Board Yes 42° 34′ 59′′ 70° 53′ 24′′ Beverly/Wenham --

64 1641 31711902-01S Surface-water withdrawal 1 Myopia Hunt Club Golf Course Yes 42° 36′ 35′′ 70° 51′ 38′′ Hamilton --

65 -- 3119000-01G Bridge Street well Hamilton Water Dept. No 42° 36′ 57′′ 70 50′ 35′′ Hamilton --

65 1651 3119000-02G School well Hamilton Water Dept. Yes 42° 36′ 44′′ 70° 50′ 07′′ Hamilton 200

66 1661 3144000-06G Essex Road well Ipswich Water Dept. Yes 42° 39′ 27′′ 70° 49′ 37′′ Ipswich 150

66 1662 3144000-07G Fellows Road well Ipswich Water Dept. Yes 42° 39′ 05′′ 70° 49′ 30′′ Ipswich 350

67 -- 31714401-01S Surface-water withdrawal 1 Corliss Brothers Farm No 42° 39′ 48′′ 70° 49′ 52′′ Ipswich --

Reach

No.

WDM

data

set 

No.

Mass. DEP

source 

No.

Source name Water supplier name

Included 

in 

model

Latitude Longitude Town

Distance 

from 

stream

(feet)
Precipitation-Runoff M

During the calibration period, Hamilton obtained 

water from two wells along Idlewild Brook (one new 

well has since been installed and is included in the 

model, but with no withdrawals specified during the 

calibration period), and a well each along the Ipswich 

River and Miles River. The combined average annual 

withdrawal from these wells during the calibration 

period was 0.79 Mgal/d. 

Reading has one of the most developed well 

fields along the Ipswich River —11 wells have a combined annual withdrawal of 1.96 Mgal/d. North 

Reading obtains water from 7 wells; 6 of these are 

along Martins Brook and 1 is along the Ipswich River. 

These wells had a combined average annual withdrawal of 0.87 Mgal/d during the calibration period. 

One of the wells along Martins Brook and the well 

along the Ipswich River were not pumped during the 

calibration period, but they were included in the model 

with no withdrawals specified during the calibration 

period.

Topsfield obtains water from a well along the 

Ipswich River and a well along Howlett Brook. These 

wells have a combined average annual withdrawal of 

1.36 Mgal/d. Total monthly withdrawals were reported 

for each well. 

Withdrawal rates for wells in Hamilton, North 

Reading, and Topsfield were obtained from the 

MADEP. Withdrawals in 1989 were unavailable and 

estimated from the average 1990–93 monthly withdrawals. Daily withdrawals were obtained by disaggregating monthly withdrawals using Wenham records as 

described below. 

Of these four towns, only Reading has a municipal wastewater system, which discharges to the ocean 

through the Massachusetts Water Resources Authority 

system; the other three towns rely on onsite septic 

systems for waste disposal.

The Thomson Country Club in North Reading 

operates 2 surface-water withdrawals for private use 

that take water directly from the Ipswich River just 

upstream of the South Middleton station. The combined average withdrawal from the two surface-water 

sources was 0.023 Mgal/d during the calibration 

period. The withdrawals generally were taken only 

during April through November each year.

Lynnfield. Lynnfield obtained its entire water 

supply from 1 well in the Wills Brook headwaters 

during the calibration period. This well had an average 

withdrawal of 0.31 Mgal/d during the period. The town 

provided daily withdrawal data from the well for the 

period 1989–97. The town installed 4 new well

Wills Brook headwaters during 1997. These wel

included in the model with no withdrawals spec

during the calibration period. 

The Sagamore Spring Golf Club, Inc., op

wells and 2 surface-water withdrawals for priva

in the Wills Brook headwaters in Lynnfield. Pum

rates for these supplies were provided by the M

and were included in the model. The combined 

withdrawal from the three wells was 0.006 Mga

and the combined average withdrawal from the 

surface-water sources was 0.053 Mgal/d during 

ibration period. The surface-water withdrawals 

ally were taken only during April through Nove

each year. Lynnfield relies on onsite septic syste

wastewater disposal. 

Lynn. Lynn (completely outside the basin

obtained water directly from the Ipswich River 

above the South Middleton station during 1989 

1993. Withdrawals averaged 3.1 Mgal/d in 1989 

0.39 Mgal/d in 1993.

Peabody. Peabody obtains water from 2 

along Norris Brook and directly from the Ipswic

about 1 mile downstream from the South Middl

station. Water from the Ipswich River is pumpe

sonally to Suntaug Lake and from there, re-dist

to Winona Pond or other reservoirs outside of th

Ipswich Basin. Under normal operation, all wat

Suntaug Lake and Winona Pond is exported fro

basin (Peter Smyrnios, Peabody Water Departm

oral commun., 1999). Only the water withdraw

the Ipswich River is included in the model. Dire

runoff to Suntaug Lake and Winona Pond were 

eled, but did not contribute to the Ipswich Basin

Municipal wastewater is discharged to the ocea

Only one of the two wells was active dur

calibration period. The monthly withdrawals fro

active well were obtained from the MADEP for 

93. Monthly withdrawals for 1989 were estimate

the average monthly withdrawals for 1990–93 p

Daily withdrawals were estimated by transform

withdrawal for each month into a daily value th

aged 0.07 Mgal/d during the calibration period. 

Danvers and Middleton. Danvers and 

Middleton obtain water from two wells and thre

water-supply reservoirs: Swan Pond, Emerson B

Reservoir, and Middleton Pond. Water is diverte

from Swan Pond and Emerson Brook Reservoir 

Middleton Pond, and from there, water is divert

the water-supply system. Swan Pond is pumped 
28 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

during October and November; at other times, the 

water level in the pond is maintained to help prevent 

dewatering of nearby residential wells. Emerson Brook 

Reservoir is pumped only when water is available (it 

usually dries in the summer) and there is storage available in Middleton Pond (Donald DeHart, Danvers 

Department of Public Works, written commun., 1998). 

Monthly water levels and curves for water level, storage volume, surface area, discharge were provided for 

each reservoir.

The two wells are adjacent to the Ipswich River 

and had a combined average withdrawal of 0.11 Mgal/d 

during the calibration period. Monthly withdrawals 

were reported for 1989 through part of 1998. Daily 

withdrawals were obtained by transforming monthly 

values into daily values. Municipal wastewater from 

Danvers is discharged to the ocean. Middleton is 

mostly unsewered and septic effluent in these areas that 

is not lost to evaporation is returned to the Ipswich 

River Basin.

Boxford. The town of Boxford has no municipal 

water-supply or wastewater systems. Residents rely on 

individual wells and onsite septic systems; thus no 

water-use activities were included in the model for the 

town.

Wenham. The town of Wenham obtains water 

from 2 wells adjacent to Idlewild Brook. Wenham provided total daily well withdrawals for 1989 through 

part of 1998. The combined daily withdrawals from 

these wells averaged 0.32 Mgal/d during the calibration 

period and are evenly divided between the two wells. 

Wastewater discharges to onsite septic systems.

Withdrawals from the Wenham wells were used 

to estimate daily withdrawals for some towns (as 

noted) where only monthly withdrawal rates were 

available. The Wenham records were considered to 

reflect the day-to-day water-supply demands in other 

towns in response to climatic conditions. Wenham 

records were not used to estimate daily ground-water 

withdrawals for Peabody, Danvers, and Middleton 

because their water supplies use both surface- and 

ground-water supplies. In systems such as these, the 

day-to-day fluctuations in ground-water pumping 

would not be the same as for a system that relies solely 

on ground-water supplies because short term increases 

in demand can be obtained from reservoir storage 

rather than increased well withdrawals.

Large day-to-day fluctuations in the Wenham 

withdrawals were probably caused by the operation of 

the town's water supply rather than user demands in 

response to climatic variations. These operation

related fluctuations were therefore removed by 

15-day moving average, centered on the 8th day 

using the record to estimate the pattern of daily 

demands for towns where only monthly records 

available. The smoothing period was determine

empirically to maintain a reasonably large varia

the daily values while eliminating the large oper

fluctuations. Daily withdrawals were computed 

wells with only monthly values by (1) computin

monthly mean withdrawal rates from the smoot

daily values at Wenham, (2) computing the ratio 

between the daily withdrawals and mean month

drawals for each day at Wenham, (3) computing 

average daily withdrawal by month for towns w

only monthly values were available, and (4) mu

ing the average daily values by the daily ratios 

computed from Wenham data. 

The variation in streamflow depletion cau

by ground-water withdrawals is substantially le

than actual well pumping rates because of the 

damping effect of aquifer storage. Figure 9 show

combined daily pumping of the two Wenham w

1989, the smoothed daily pumping rate (pattern 

to estimate daily pumping rates in other towns)

the calculated depletion of flow in Idlewild Bro

(RCHRES no. 49, fig. 8) caused by ground-wat

withdrawals. The streamflow depletion is comp

using the STRMDEPL program described in 

Appendix A.

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

FLOW, IN CUBIC FEET PER SECOND

COMPUTED STREAMFLOW DEPLETION

SMOOTHED PUMPING

ACTUAL PUMPING

J FMAMJ J A SON

1989

Figure 9. Combined actual and 15-day moving avera

daily ground-water withdrawals from two Wenham w

supply wells, and the calculated streamflow depletio

flow in Idlewild Brook, Mass., 1989.
Precipitation-Runoff M

Salem and Beverly. Salem and Beverly obtain 

their water from the Salem-Beverly Water-Supply 

Board (SBWSB), which depends entirely on surfacewater sources in the Ipswich River Basin. The SBWSB 

maintains three reservoirs in the basin: Putnamville 

Reservoir, Longham Reservoir, and Wenham Lake. 

Water is withdrawn from the Ipswich River through the 

3-mile long Salem-Beverly Canal to an intake that 

pumps water into the Putnamville Reservoir and 

Wenham Lake for storage and later use. Water in 

Putnamville Reservoir is diverted to Wenham Lake 

when Wenham Lake storage runs low. Water is also 

diverted from Longham Reservoir, near the headwaters 

of the Miles River subbasin, to Wenham Lake. 

The SBWSB supplied daily time series for the 

period 1989 through 1997 of diversions from the 

Ipswich River to Putnamville Reservoir and Wenham 

Lake, diversions from Putnamville Reservoir and 

Longham Reservoir to Wenham Lake, and releases 

from Longham Reservoir to the Miles River. The 

SBWSB provided monthly time series of pumping 

from Wenham Lake, and water levels and capacity 

tables for its reservoirs. During the calibration 

period, the SBWSB diverted an annual average of 

1,787 Mgal from the Ipswich River, and 1,187 Mgal 

from Longham Reservoir. Wastewater for Salem and 

Beverly is discharged to the ocean.

Ipswich. The town of Ipswich obtains water 

from three wells adjacent to Ipswich River and two 

wells adjacent to Miles River. Monthly withdrawals 

were reported for 1989, and daily withdrawals were 

reported for 1990 through part of 1998 for each well. 

The town also uses water sources in the Parker River 

Basin, but these were not modeled. Daily withdrawals 

were obtained for 1989 by disaggregating monthly 

withdrawals using Wenham records as described 

above. The combined average withdrawal from 

Ipswich wells in the Ipswich River Basin during the 

calibration period was 0.21 Mgal/d. Municipal sewers 

serve about half the population and the treated effluent 

is discharged to the Ipswich River below Sylvania 

Dam.

Andover, Billerica, North Andover, and 

Tewksbury. No municipal water supplies or wastewater returns were modeled for the towns of Andover, Billerica, North Andover, and Tewksbury. These towns 

obtain municipal water supplies outside of the Ipswich 

Basin and in areas that are sewered, wastewaters are 

discharged outside of the basin. 

Representation of the Basin

The physical and spatial representation o

basin in the model is defined by the combinatio

HRUs (PERLNDs and IMPLNDs), their contrib

area to a reach, and the linkage of one reach to a

The process of defining HRUs, their linkage to r

and the linkage of reaches to each other often is 

referred to as the schematization or discretizatio

basin. A Geographic Information System (GIS) 

used to discretize the watershed. Basin boundar

many of the reaches in the model were available 

state-wide digital data layer constructed by the 

and MassGIS (Massachusetts Geographic Infor

System). Basin boundaries for reaches that wer

available from this data layer were delineated fr

1:25,000-scale Digital Elevation Model (DEM) 

in some cases, they were digitized by hand from 

1:25,000-scale USGS topographic maps. Other 

layers used in the discretization process were ob

from MassGIS, and include 1:125,000-scale sur

geology, 1:25,000-scale land use, 1:25,000-scal

hydrography, and 1:5,000-scale wetlands. Thes

layers, including detailed descriptions, can be o

at MassGIS (http://www.state.ma.us/mgis/).

The spatial data were simplified and grou

obtain categories that were considered importan

hydrology of the watershed. The surficial-geolo

layer was simplified from 7 types of materials in

the basis of permeability and storage characteri

(1) sand and gravel, (2) till and bedrock, and (3

grained or alluvial deposits. The land-use data l

was combined with the wetland data layer and t

simplified from 62 categories to 8 land-use cate

(1) forest, (2) open irrigated, (3) open-non-irrig

(4) open water, (5) forested wetland, (6) non-fo

wetland, (7) low-density residential, (8) high-de

residential, and (9) commercial. HRUs were ob

by combining the surficial geology and the simp

land-use data layers. Intersection of the combin

surficial-geology and land-use data layers with 

basin delineations yielded the area of each HRU 

each subbasin.

Hydrologic Response Units

Fourteen out of 27 possible combinations 

surficial geology and land use covered areas suf

ciently large to warrant unique HRUs. Combina

surficial geology and land use with areas less th

about 1 percent of the basin area were grouped 

HRU with the most similar characteristics. For 
30 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

instance, open-non-irrigated land accounted for about 1 

percent of the watershed area; therefore, this category 

was combined with the open-irrigated category. From 

the initial 14 HRUs, four additional HRUs that represent residential areas on public water and septic systems and two HRUs that represent impervious areas 

were developed as described below.

Impervious Areas (IMPLNDs)

Impervious areas are any surfaces that prohibit 

infiltration of water into the ground, such as building 

roofs, paved roads, and parking lots. Water on some 

impervious surfaces can eventually infiltrate into the 

ground because these surfaces drain onto pervious 

surfaces that allow infiltration. In the HSPF model, 

IMPLNDs are used to simulate effective impervious 

areas, which are impervious surfaces that drain directly 

to streams, and thus produce only surface runoff. Noneffective impervious areas, which are impervious surfaces that drain to pervious surfaces, are incorporated 

into one of the disturbed PERLND types as described 

later. In large basins such as the Ipswich, values for 

imperviousness, and particularly effective imperviousness, are difficult to obtain. Initial estimates of the 

effective impervious area were made as a percentage of 

commercial land use and different classes of residential 

land use as indicated in table 6. High-density residential land use represents multi-family residential and 

single-family residential on lots with areas smaller than 

or equal to 0.5 acre. Low-density residential land use 

represents single-family homes on lots larger than 

0.5 acre.

Initial estimates of effective impervious a

similar to those reported by Dinicola (1990) an

and Veenhuis (1983) for similar land-use types. 

final effective impervious area was obtained pri

by calibration of small summer storms that gen

runoff mostly from effective impervious surface

ever, other factors including the overall respons

of the hydrograph to precipitation and water bu

were considered because small summer storms c

be affected by surface retention, widely distribu

small flow-control structures, precipitation vari

and other factors. 

Two IMPLND types were used in the mo

(1) commercial, and (2) residential which repre

the combined impervious area from high- and 

low-density residential areas. The calibrated eff

impervious area was decreased from the initial 

mated values by 20 percent for commercial area

by 50 percent for residential areas. Although, ab

percent of the basin is classified as developed, t

mated total effective impervious area as a perce

the total basin area is 6.8 at the South Middleto

tion, 4.6 at the Ipswich station, and 4.4 at Sylva

Dam.

Pervious Areas (PERLNDs)

Pervious areas are any surface that allow

infiltration and are represented by 14 HRUs init

obtained by the intersection of data layers for su

geology and land-use types, plus the 4 new HRU

to represent different residential areas on public 

water and onsite septic systems (described later

Water and wetlands (nos. 16, 17, and 18 in tabl

were not used as PERLND types in the final mo

but are included in the table for reference. Gene

descriptions and areas of each PERLND for the 

drainage area above the South Middleton statio

Ipswich station, and the Sylvania Dam are pres

in table 7. Areas of HRUs as a percentage of the 

age area to each station and the Sylvania Dam a

shown in figure 10. This plot indicates that mos

the HRUs are evenly distributed throughout the 

shed. A small area (about 0.6 mi2) that drains to 

Ipswich station was excluded from the model b

it drains directly to a supply reservoir that expo

water from the basin.

Table 6. Estimated effective impervious area by land use, 

Ipswich River Basin, Mass.

[MassGIS, Massachusetts Geographic Information System]

Land use 

classification

Area of 

basin as

classified 

by

MassGIS

(acres)

Estimated

percent of area 

that is effective 

impervious

Effective

impervious 

area

(acres)

Initial Final Initial Final

Commercial ....... 3,586 79 63 2,844 2,275

High-density

residential ...... 11,492 27 14 3,157 1,579

Low-density

residential ...... 14,483 5 2.5 724 362

Total ................... 29,562 6,725 4,216
Precipitation-Runoff M

Development of PERLND Types

Twelve PERLND types were developed for open 

space: 3 for undeveloped open areas on different surficial deposits and 9 for open areas associated with 

development (table 7). Open area associated with 

development represents the green space between buildings and paved surfaces that likely receives runoff from 

adjacent impervious surfaces. These areas are considered disturbed; therefore, infiltration and soil-water 

storage was decreased relative to undeveloped open 

HRUs for similar surficial geology types. Four 

PERLND types were created for open residential areas 

to represent two different development densities over 

two types of surficial geology. One PERLND type 

was created for open commercial areas. Duplic

PERLND types are specified for each of the fou

residential area PERLNDs to represent areas on 

water and onsite septic systems described below

PERLND types include forested areas over san

gravel, till, and alluvial deposits. 

Hydrologic characteristics are generally s

for PERLNDs with similar surficial geology; ho

upper- and lower-zone storage and infiltration i

for disturbed open PERLNDs relative to similar 

turbed open PERLNDs. Lower-zone evapotrans

tion is highest in forested PERLND types and lo

undisturbed open PERLND types. The calibrate

parameter values for each HRU are given in the 

file listed in Appendix B.

Table 7. Hydrologic Response Units (HRUs) used to represent the Ipswich River Basin and their contributing areas to 

South Middleton and Ipswich stations and to Sylvania Dam, Mass.

[Shaded rows indicate area incorporated into model as river reaches (RCHRES); mi2, square mile]

HRU

Area in acres

Surficial

geology

South Land use

Middleton

station

Ipswich

station

Sylvania

Dam

Total as a 

percent

of basin

PERLND 1 2,990 9,312 12,534 13 Sand and gravel Forest

PERLND 2 377 1,762 3,554 3.7 Sand and gravel Open

PERLND 3 675 2,391 3,879 4.1 Sand and gravel Open, low density residential

PERLND 4 1,416 2,461 3,028 3.2 Sand and gravel Open, low density residential on publ

and onsite septic

PERLND 5 1,456 2,761 3,687 3.9 Sand and gravel Open, high density residential

PERLND 6 1,102 1,864 2,250 2.4 Sand and gravel Open, high density residential on pub

and onsite septic

PERLND 7 626 1,125 1,280 1.3 Sand and gravel Open, commercial

PERLND 8 4,777 20,202 22,118 23 Till Forest

PERLND 9 328 2,170 2,658 2.8 Till Open

PERLND 10 1,023 3,667 4,238 4.4 Till Open, low density residential 

PERLND 11 1,814 3,154 3,373 3.5 Till Open, low density residential on publ

and onsite septic

PERLND 12 989 1,991 2,290 2.4 Till Open, high density residential 

PERLND 13 1,391 2,259 2,374 2.5 Till Open, high density residential on pub

and onsite septic

PERLND 14 939 1,273 1,630 1.7 Alluvial Forest

PERLND 15 121 171 400 .4 Alluvial Open

16 403 1,683 2,384 2.5 Water

17 1,765 5,293 6,680 7.0 Wetland, non-forested

18 4,228 11,691 13,119 14 Wetland, forested

IMPLND 1 817 1,707 1,941 2.0 Impervious residential 

IMPLND 2 1112 2,000 2,275 2.4 Impervious commercial

Total (mi2) 44.3 124.2 149.5
32 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

SOUTH MIDDL

 STATION

IPSWICH STAT

SLYVANIA DA

EXPLANAT

HYDROLOGIC RESPONSE UNIT AREAS AS A 

PERCENT OF DRAINAGE AREA

0

5

10

15

20

25

30

35

Forest

Open

Low density

Low density

High density

High density

Commercial

Overlying 

Sand and gravel

Forest

Open

Low density

Low density

High density

High density

Forest

Open

Open water

Forested wetland

 Non-forested wetland

Residential

Commercial

Overlying 

Till and bedrock

Pervious areas (PERLNDs)

Impervious areas

(IMPLNDs)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1 2

PERLND NUMBER IMPLND

NUMBER

Overlying

Alluvial

Residential Residential

On public 

water and 

onsite septic

On public 

water and 

onsite septic

Residential Areas on Public Water and 

Onsite Septic Systems

Residential areas on public water and onsite 

septic systems were considered to represent a net 

inflow of water to the area, whereas residential areas on 

public water and public sewer and residential areas on 

private wells and onsite septic systems were considered 

to have no net water gain or loss. To account for residential areas on public water and septic systems, 1990 

TIGER census-tract data (http://www.census.gov/) 

were used to determine the number of houses on public 

water but not public sewer. The census-tract data were 

used because public-utility maps were not readily 

available across the basin. The census-tract data indicated that about half the households in the basin are on 

public water but not public sewer. Several assumptions 

were made to relate the census-tract data with land-use 

information to develop HRUs served by public water 

but not public sewer.

The original MassGIS land-use cover had 4 categories of residential land use: (1) multi-family, (2) less 

than 1/4 acre, (3) 1/4 to 1/2 acre, and (4) greater than 

1/2 acre. Households on public water and onsite 

systems were assumed only to be associated wi

dential areas of 1/4 to 1/2 acre and greater than 

(moderate and low density residential developm

respectively). Multifamily residential and high-

residential areas (lots less than 1/4 acre) were a

to have both public water and public sewer.

Low- and moderate-density residential la

areas were obtained for each census tract. The n

of homes on public water and onsite septic syst

each census tract were apportioned to that tract

of low and moderate-density residential develop

It was further assumed that the average lot size 

moderate-density development is 1/3 acre and f

density development is 2/3 acre, and that house

more than 1 acre were not classified as resident

residential areas affected by public water and o

septic systems were then calculated by census t

Subbasin areas of residential land use wit

public water and onsite septic systems were cal

by a weighted average of the census tract areas 

Figure 10. Areas of hydrologic response units in the Hydrological Simulation Program-FORTRAN (HSPF) model of 

Ipswich River Basin, Mass. as a percentage of the drainage area above the South Middleton and Ipswich stations a

above Sylvania Dam, Mass.
Precipitation-Runoff M

each subbasin. The portion of areas on public water and 

onsite septic systems that overlay different types of 

surficial geology were calculated using the portion of 

area of different residential development densities over 

different surficial geology types in each subbasin. 

Minor adjustments in the calculated area were made to 

correct for imprecision in the method, so that the total 

residential area by subbasin and surficial geology 

remained the same as the area originally derived from 

the MassGIS land-use data.

Four new HRUs were added to the model to represent residential areas on public water and onsite 

septic systems: (1) high-density development over sand 

and gravel, (2) low-density development over sand and 

gravel, (3) high-density development over till, and 

(4) low-density development over till. These HRUs are 

identical to four corresponding residential HRUs that 

are not affected by public water and onsite septic systems; the difference between the two groups of HRUs 

is that a small quantity of water is added to the lowersoil zone as inflow from septic effluent to represent the 

average household water use. Low-density residential 

areas on public water and onsite septic systems were 

shifted from the area of low-density residential HRUs 

with similar surficial geology. Moderate-density 

residential areas on public water and septic were 

shifted from the areas of high-density residential HRUs 

with similar surficial geology. 

The quantity of septic effluent was calculated 

by multiplying the average occupancy per household 

(average of 3 persons occupancy for homes on public 

water and onsite septic systems from the census-tract 

data) by the average water use of 79 gal/d per person 

(Massachusetts Department of Environmental 

Management, 1987a). The resulting 237 gal/d per 

household was distributed over the 1/3 and 2/3 acres 

for moderate- and low-density residential development, 

respectively. This value was converted to inch per 

hour per acre and was added to the affected HRUs −

1.09x10-3 in/hr/acre for moderate-density residential 

areas and 5.45x10-4 in/hr/acre for low-density residential areas. This small quantity of water was added to the 

applicable HRUs as inflow to the lower-zone storage 

(LZLI) by means of an external time-series. Applying 

the septic effluent to the lower-soil zone was considered the most appropriate because septic leach fields 

are typically installed in this part of the soil horizon. 

Inflow to the lower-soil zone is not available to runoff 

or discharge as interflow or active ground water flow. 

Rather, septic effluent directed into the lower-zone 

storage means there is less opportunity for infilt

moisture to be held in the lower-zone storage be

the added inflow from the septic effluent will ke

storage closer to its capacity then would otherw

occur. As a result, more infiltrated atmospheric 

ture will reach the active ground-water storage i

with septic effluent then in similar areas withou

effluent. 

Water added to the basin in areas on publi

and onsite septic systems is not linked to any pa

source. Thus, the public water-supply source, w

inside or outside the basin, is inconsequential to 

water added as septic effluent. For example, the 

of North Reading, which is not sewered, supple

its water supply during the summer from the tow

Andover system, which obtains water from the 

cent Merrimack River Basin.The septic effluent 

North Reading is treated by the model as an infl

the Ipswich Basin all year round, whether the w

originated from the Merrimack Basin in the sum

from within the Ipswich Basin.

The estimated septic effluent rate is 9.6 in

high-density residential areas and 4.8 in/yr on l

density residential areas; these rates represent a

and 10 percent of the average annual moisture-s

to these areas, respectively. Residential areas on 

water and onsite septic compose an estimated 2

and 12 percent of the drainage area to the South 

Middleton and Ipswich stations, and the Sylvani

respectively. If the septic effluent were to reach 

tions and Sylvania Dam this would comprise ab

percent of the total runoff to the South Middleto

tion and about 4 percent each of the total runoff 

Ipswich station and to Sylvania Dam, but these 

do not consider the septic effluent lost to evapo

ration. Septic effluent is estimated to be 3 percen

total moisture supply to the South Middleton st

and about 2 percent each of the moisture supply 

Ipswich station and to Sylvania Dam. 

Stream Reaches

The Ipswich River and its main tributarie

were segmented into 67 reaches (fig. 8). The re

segmentation was determined based on hydrolo

water use, and in some cases, habitat considerat

A list of these reaches is provided in table 8. W

from RCHRES 21 (Suntaug Lake) is diverted o

the basin for the town of Peabody water supply

reach was included in the model, but water doe
34 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

contribute to the Ipswich River, so that the model can 

be used for firm yield analysis of this supply in the 

future. RCHRES 22 (Winona Pond) was not explicitly 

simulated because all water is diverted into the 

Peabody supply. The natural drainage to the Winona 

Pond is diverted around the pond; therefore, the overland drainage area in RCHRES 22 was combined with 

RCHRES 23. Methods used to define the reach geometry that control the storage-discharge characteristics of 

reaches and the incorporation of wetlands as RCHRES 

are described below. 

Hydraulic Characteristics (FTABLEs)

FTABLEs define the relations among depth, 

surface area, volume, and discharge of reaches used in 

the kinematic wave routing of flow downstream. 

FTABLEs are specified for the outflow gate used to 

route water downstream; the first outflow gate was used 

for reaches with no water withdrawals, and typically 

the second outflow gate was used for reaches with 

water withdrawals.

The relations in the FTABLEs depend on the 

hydraulic properties of the reaches. The relation 

between depth and discharge is usually defined by the 

hydraulic properties at the downstream end of the 

reach, but the discharge-volume relation is a function 

of the hydraulic properties of the entire reach. Hydraulic properties such as channel geometry, length, slope, 

and roughness, were determined from available data 

for each reach, or estimated on the basis of the properties of similar reaches. The hydraulic properties were 

used to solve Manning's equation for open-channel 

flow to develop the FTABLEs.

Reach lengths and slopes were determined from 

digital map layers. Node locations were digitized into a 

map layer. This layer was intersected with the stream 

map layer to determine the distances between nodes, 

and intersected with the DEM data to determine the 

elevation at each node and at the stream source in headwaters areas. Differences in elevation between nodes, 

or between stream sources and nodes, were divided by 

stream lengths to obtain reach slopes.

Channel cross-section data were obtained 

from Federal Emergency Management Agency 

(FEMA) flood-prone area maps and survey data

section data were also obtained from streamflow 

surements at the gaging stations and partial-rec

sites, site surveys, and ratings of structures prov

water suppliers. Data were available for several 

hundred cross sections in the basin from FEMA 

ies. The Channel Geometry Analysis Program (

(Regan and Schaffranek, 1985) was used to calc

the stage-storage-discharge relations from mult

cross sections and estimates of channel roughne

stage-discharge relations obtained from CGAP 

monly were adjusted on the basis of rating curv

developed for the gaging stations and partial-re

sites that coincided with node locations (table 8

measurements defined the low-flow end of the re

better than the FEMA data because usually few 

readings were taken in the low-flow channel for 

FEMA studies, whereas discharge measuremen

usually contain at least 25 such readings.

FEMA cross-sections and discharge mea

ments often were not available for the small trib

and in the headwater areas of the basin. In these 

FTABLEs were constructed for the reaches by u

the XSECT program (AquaTerra Consultants, 1

written commun.) XSECT assumes a trapezoid

nel configuration, and solves Manning's equatio

on channel slope, length, height, bottom and top 

flood-plain slope, and channel and flood-plain r

ness. Channel length and slope for these reache

determined from GIS analysis like all other cro

tions. Other parameters for XSECT were determ

from site inspections and by transfer of informa

from similar reaches where the parameters were 

known. XSECT also was used to develop FTAB

some sections of the main channel of the Ipswic

River, where FEMA cross-sections were inadeq

spaced to provide reasonable results with the C

program.
Precipitation-Runoff M

Table 8. Stream reaches (RCHRES) in the Hydrological Simulation Program-FORTRAN model of the Ipswich River Ba

Mass.—Continued

Reach

No.

USGS

station

No.

Downstream node 

location Reach name

Direct

drainage

area

Total

drainage

area

U

Latitude Longitude

1 01101300 42° 32′ 13′′ 71° 09′ 40′′ Maple Meadow Brook at Route 38, Wilmington 4.03 4.03 

2 -- 42° 33′ 07′′ 71° 09′ 27′′ Maple Meadow Brook above mouth, Wilmington .66 4.69 

3 -- 42° 33′ 08′′ 71° 09′ 28′′ Mill Brook above Maple Meadow Brook, Wilmington 3.51 3.51 

4 -- 42° 33′ 13′′ 71° 08′ 41′′ Mill Brook above Lubbers Brook, Wilmington .49 8.68 

5 01101320 42° 33′ 50′′ 71° 11′ 05′′ Lubbers Brook above Main Street (Route 38), Wilmington 2.83 2.83 

6 -- 42° 34′ 12′′ 71° 09′ 31′′ Lubbers Brook above Middlesex Avenue, Wilmington 1.89 4.71 

7 -- 42° 33′ 14′′ 70° 08′ 41′′ Lubbers Brook above mouth, Wilmington .90 5.61 

8 -- 42° 33′ 40′′ 71° 05′ 40′′ Ipswich River at Mill Street near Reading 4.19 18.5 

9 -- 42° 33′ 58′′ 71° 06′ 16′′ Bear Meadow Brook above mouth near Reading 4.83 4.83 

10 -- 42° 34′ 15′′ 71° 06′ 03′′ Ipswich River above Martins Brook, North Reading .42 23.7 

11 01101380 42° 36′ 42′′ 71° 05′ 58′′ Skug River at Harold Parker Road, Andover 2.51 2.51 

12 01101395 42° 34′ 47′′ 71° 08′ 22′′ Martins Brook at Route 62, North Reading 7.85 10.4 

13 01101400 42° 34′ 16′′ 71° 06′ 04′′ Martins Brook above mouth, North Reading 2.97 13.3 

14 -- 42° 34′ 35′′ 71° 04′ 14′′ Ipswich River above unnamed tributary, North Reading 1.02 38.1 

15 01101460 42° 34′ 36′′ 71° 04′ 15′′ Ipswich River Tributary at North Reading 2.08 2.08 

16 -- 42° 34′ 16′′ 71° 02′ 58′′ Ipswich River above Wills Brook, North Reading 1.10 41.2 

17 01101480 42° 34′ 13′′ 71° 02′ 57′′ Wills Brook near North Reading 1.76 1.76 

18 -- 42° 34′ 11′′ 71° 01′ 51′′ Ipswich River at South Middleton Dam, near Lynnfield .78 43.8 

19 01101500 42° 34′ 10′′ 71° 01′ 39′′ Ipswich River at South Middleton gaging station .61 44.4 

20 -- 42° 34′ 01′′ 70° 59′ 56′′ Ipswich River above Norris Brook, Danvers 1.18 45.6 

21 -- 42° 31′ 33′′ 71° 00′ 30′′ Norris Brook at Suntaug Lake Outlet, Peabody .50 .50 

22 -- 42° 32′ 14′′ 71° 00′ 28′′ Norris Brook at Winona Pond Outlet, Peabody .93 1.44 

23 01101510 42° 33′ 14′′ 71° 00′ 15′′ Norris Brook above Russell Street, Peabody 2.66 4.10 

24 -- 42° 34′ 00′′ 70° 59′ 54′′ Norris Brook above mouth, Danvers .42 4.52 

25 -- 42° 34′ 40′′ 70° 59′ 37′′ Ipswich River at Old Log Bridge Road near Middleton 1.92 52.0 

26 -- 42° 35′ 40′′ 71° 01′ 13′′ Middleton Pond Outlet, Middleton 1.53 1.53 

27 -- 42° 35′ 18′′ 71° 00′ 03′′ Middleton Pond Brook, Middleton .66 2.19 

28 01101540 42° 35′ 45′′ 70° 59′ 49′′ Ipswich River at Maple Street (Route 62), Middleton 1.64 55.8 

29 -- 42° 36′ 38′′ 70° 59′ 53′′ Ipswich River above Emerson Brook, Middleton .74 56.6 

30 -- 42° 36′ 14′′ 71° 02′ 06′′ Emerson Brook Reservoir, Middleton 4.71 4.71 

31 01101550 42° 36′ 37′′ 70° 59′ 56′′ Emerson Brook above mouth, Middleton 1.66 6.37 

32 01101610 42° 37′ 58′′ 71° 02′ 35′′ Boston Brook at Sharpners Pond Road near North Andover 5.59 5.59 

33 01101650 42° 37′ 15′′ 71° 01′ 14′′ Boston Brook at Liberty Road near Middleton 2.57 8.16 

34 -- 42° 36′ 40′′ 70° 59′ 55′′ Boston Brook above mouth, Middleton 2.76 10.9 

35 -- 42° 37′ 17′′ 70° 58′ 52′′ Ipswich River above Nichols Brook, Middleton 1.54 75.4 

Table 8. Stream reaches (RCHRES) in the Hydrological Simulation Program-FORTRAN model of the Ipswich River Ba

Mass.

[Total drainage area includes the direct drainage area to the reach plus the drainage area above the reach. Area is in square miles; No., number; US

Geological Survey; --, means station number not assigned or no upstream reach;°- degrees, ′ - minutes, ′′- seconds]
36 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

36 -- 42° 37′ 16′′ 70° 58′ 51′′ Nichols Brook, Middleton 3.09 3.09 

37 -- 42° 37′ 35′′ 70° 58′ 07′′ Ipswich River above Fish Brook, Topsfield .77 79.3 

38 01101720 42° 39′ 53′′ 71° 01′ 42′′ Fish Brook near Boxford 9.86 9.86 

39 01101740 42° 38′ 93′′ 70° 59′ 20′′ Fish Brook at Lockwood Lane near Boxford 4.09 14.0 

40 -- 42° 37′ 36′′ 70° 58′ 07′′ Fish Brook above mouth 3.88 17.8 

41 -- 42° 37′ 03′′ 70° 56′ 32′′ Ipswich River at riffle site above Route 97, Topsfield 1.51 98.6 

42 -- 42° 37′ 37′′ 70° 56′ 24′′ Cleveland Brook, Topsfield 1.07 1.07 

43 -- 42° 37′ 25′′ 70° 55′ 56′′ Ipswich River above Salem–Beverly Canal, Topsfield .64 100 

44 -- 42° 36′ 24′′ 70° 54′ 05′′ Salem–Beverly Canal intake, Wenham .85 .85 

45 -- 42° 36′ 10′′ 70° 56′ 24′′ Putnamville Reservoir Outlet, Topsfield .87 .87 

46 -- 42° 37′ 03′′ 70° 55′ 20′′ Putnamville Reservoir Brook above Salem–Beverly Canal, 

Wenham

2.76 3.63 

47 -- 42° 37′ 24′′ 70° 55′ 55′′ Salem–Beverly Canal outlet to Ipswich River, Topsfield .18 4.67 

48 -- 42° 37′ 50′′ 70° 54′ 26′′ Ipswich River above Idlewild Brook, Hamilton 1.03 106 

49 -- 42° 37′ 49′′ 70° 54 ′25′′ Idlewild Brook, Hamilton 2.60 2.60 

50 -- 42° 39′ 12′′ 70° 54′ 55′′ Ipswich River above Howlett Brook, Topsfield 2.35 111 

51 01101840 42° 40′ 17′′ 70° 58′ 52′′ Pye Brook at Lowe Pond Outlet, East Boxford 2.85 2.85 

52 01101850 42° 39′17′′ 70 °57′ 12′′ Pye Brook near Topsfield 3.80 6.65 

53 01101900 42° 39′ 17′′ 70° 54′ 54′′ Howlett Brook at mouth, Topsfield 4.22 10.9 

54 01101950 42° 39′ 37′′ 70° 54′ 14′′ Gravelly Brook, Ipswich 2.28 2.28 

55 -- 42° 39′ 34′′ 70° 53′ 40′′ Ipswich River at Willowdale Dam, Ipswich .73 125 

56 01102000 42° 39′ 34′′ 70° 53′ 39′′ Ipswich River at Ipswich gaging station .01 125 

57 -- 42° 39′ 15′′ 70° 52′ 55′′ Ipswich River above Black Brook, Hamilton .42 125 

58 -- 42° 39′ 14′′ 70° 52′ 54′′ Black Brook, Hamilton 3.19 3.19 

59 01102008 42° 39′ 29′′ 70° 51′ 45′′ Ipswich River at Mill Road near Ipswich 1.11 130 

60 -- 42° 39′ 50′′ 70° 50′ 49′′ Ipswich River above Miles River, Ipswich .52 130 

61 -- 42° 35′ 26′′ 70° 52′ 12′′ Longham Reservoir Outlet, Wenham 3.58 3.58 

62 -- 42° 35′ 41′′ 70° 53′ 19′′ Wenham Lake Outlet, Wenham 2.20 2.20 

63 01102009 42° 36′ 01′′ 70° 52′ 29′′ Miles River above Larch Row, Wenham 1.78 7.56 

64 01102010 42° 36′ 58′′ 70° 51′ 09′′ Miles River above Bridge Street at Hamilton 2.15 9.71 

65 -- 42° 38′ 43′′ 70° 49′ 54′′ Miles River above Gardner Street, Hamilton 3.86 13.6 

66 -- 42° 39′ 49′′ 70° 50′ 47′′ Miles River above mouth, Ipswich 3.49 17.1 

67 -- 42° 40′ 39′′ 70° 50′ 17′′ Ipswich River above dam, Ipswich 2.33 149 

Table 8. Stream reaches (RCHRES) in the Hydrological Simulation Program-FORTRAN model of the Ipswich River Ba

Mass.—Continued

Reach

No.

USGS

station

No.

Downstream node 

location Reach name

Direct

drainage

area

Total

drainage

area

U

Latitude Longitude
Precipitation-Runoff M

Stage-discharge ratings were supplied for reservoirs operated by Danvers and Middleton, and by the 

SBWSB. These ratings were used to construct the 

FTABLEs for reservoir outlets. Site surveys were also 

used to develop FTABLEs for some structures, such as 

node 12 (a weir on Martins Brook) and at node 51 (the 

dam outlet from Lowe Pond on Pye Brook).

Wetlands

In the initial model development, wetlands were 

simulated as two unique PERLND types: (1) forested 

wetland, and (2) non-forested wetlands. Early calibration results indicated that the simulated hydrographs 

were much more responsive to precipitation and snowmelt than the observed flows at both stations, even after 

PERLND storage- and infiltration-parameter values 

were set beyond reasonable limits. These results indicate that the wetlands and open water, which account 

for about 21 percent of the total basin area, are an 

important storage component in the watershed. To 

account for this storage, wetlands and open water were 

treated as “virtual” RCHRESs, RCHRESs with no 

atmospheric water gains or losses. Virtual RCHRESs 

were developed for most subbasins, and represent the 

combined storage of all wetlands and open water in the 

subbasin not already considered in the reach FTABLE. 

All PERLNDs and IMPLNDs in the subbasin were 

assumed to drain into the virtual reach before draining 

into channel RCHRES.

Simulation of wetlands and open water as virtual 

RCHRESs yielded good results for flows at the South 

Middleton station, however, low flows at the Ipswich 

station were initially oversimulated. It was hypothesized that because outflows from Massachusetts's wetlands are dominated by evapotranspiration (ET) and 

ground-water seepage (Lent and others, 1997) more 

water needs to be lost through ET than could be 

obtained by simulating wetlands as PERLNDs and 

virtual RCHRES. In these simulations, ET loss 

ited to precipitation falling directly on wetlands 

lated as PERLNDs) minus the water that outflow

the wetland. The available moisture for ET loss 

lands is typically much larger than just the direc

cipitation because wetlands receive both surfac

subsurface lateral flows from surrounding upgra

areas. This was evident in the over-simulated flo

the Ipswich station because ET from the large, p

ally wet, Wenham Swamp (fig. 4) appears to ha

artificially limited by the available water.

Wetlands and open water were subsequen

simulated as RCHRESs (numbered 101 to 167) 

atmospheric gains and losses and inflows from 

adjacent overland PERLNDs and IMPLNDs. To 

account for the combined area of wetlands and 

water, the surface area in the RCHRES FTABL

set equal to the corresponding area of wetlands 

open water previously simulated as PERLNDs 

16, 17, and 18 in table 7) for that reach. Storage

charge characteristics of the wetland RCHRES 

obtained empirically by matching the simulated 

observed hydrographs. Wetlands simulated as 

RCHRES yielded a good fit between simulated 

observed flows at both stations; however, low fl

both stations were under simulated instead of o

ulated as previously described. This under-simu

resulted because the model treated all water ent

the wetland RCHRES as available for ET with 

tively large surface area to evaporate from. As a 

quence, during periods of low precipitation and 

potential ET (low flow periods), almost all the w

draining to the wetland RCHRES was lost to ET

actuality, water drains to wetlands as surface ru

interflow, and base flow; hence ET from interflo

base flow would be limited. 
38 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Within the model, ET from RCHRES can be limited only by decreasing potential ET or decreasing the 

surface area in which ET is acting. A variable surface 

area was believed to represent actual conditions better 

because the free-water surface area likely decreases 

during periods of low flow. This approach yielded good 

results after an empirical adjustment was made of the 

FTABLE surface area for wetland RCHRES for flows 

below 0.5 ft3/s. 

Wetlands are an important influence on stream 

hydrology, as evidenced in the extensive literature 

on wetland functions (Lent and others, 1997; Hunt 

and others, 1996; Krabbenhoft and Webster, 1995; 

Anderson and Cheng, 1993; Mills and Zwarich, 1986). 

The effects of wetlands on stream hydrology in the 

Ipswich River Basin are evident in the different results 

obtained by the variety of methods used to simulate 

this feature, as described above. Wetlands simulated 

as RCHRES yielded good results, but the wetland 

storage-discharge characteristics, flow-path characteristics, and the interaction between ground water and 

surface water in these wetlands are largely unknown 

and should be considered in future hydrologic investigations of the Ipswich River Basin. Also, simulating 

wetlands as a RCHRES with a variable area introduces 

a structural error into the model because the drainage 

area that receives precipitation decreases during periods of low flow. As additional data on the hydrology of 

the wetlands in the basin become available, the use of a 

new module (HSPF version 12 beta, Aquaterra, Inc., 

written commun., 1999) for simulating water budgets 

in areas with high water tables and low gradients could 

be considered. Use of this module requires time-series 

data for ground-water levels in wetlands, which were 

not available for this study. 

Water Withdrawals

Time series of total ground-water and surfacewater withdrawals were developed for each reach 

where withdrawals were known to be substantial 

(table 5). The total water withdrawal was entered as a 

single data set for each affected reach in the WDM file 

(DSNs 101 to 167 are used to specify the total water 

withdrawal corresponding to RCHRESs 1 to 67, 

respectively). The model calibration included 23 

RCHRESs (1, 5, 8, 12, 13, 17, 18, 20, 23, 26, 30, 37, 

44, 45, 49, 50, 53, 59, 61, 62, 63, 64, and 66) with 

water withdrawals. The WDM file and model UCI files 

have been designed so that additional withdrawals can 

be added easily to other RCHRESs. 

Water withdrawals are read into the mode

EXT SOURCE block (external source) of the U

and are the time-dependent volume demands pa

the first outflow gate in a RCHRES. These withd

must be satisfied before water can exit from the 

outflow gate, which, in most cases, is the water 

to the downstream reach. Water in reaches with 

water withdrawals exits through a single outflow 

Several reaches (RCHRESs 30, 44, and 61) use

outflow gates. In RCHRES 30 separate outflow 

were specified for withdrawals from: (1) Swan 

(2) Emerson Brook Reservoir, and (3) downstre

routing. 

Flows in the Salem-Beverly Canal (RCHR

fig. 8) can reverse if withdrawals from the Salem

Beverly Water-Supply Board (SBWSB) are hig

enough. When the SBWSB is not pumping or if 

pump rate is less than the flow of water into the 

from its 4.7 mi2 drainage area (subbasins for 

RCHRESs 44, 45, 46, and 47), water flows into 

Ipswich River at the upstream end of RCHRES 

When the SBWSB is pumping and the flow into 

canal from its drainage area is less than the with

rate, water will flow into the canal from the Ipsw

River. Water withdrawn from the Ipswich River 

taken from the downstream end of RCHRES 43 

(upstream end of RCHRES 48). SBWSB dema

are further complicated because water is diverte

both Wenham Lake (RCHRES 62) and Putnam

Reservoir (RCHRES 45).

HSPF cannot simulate flow reversals; the

the representation of the SBWSB withdrawals w

simplified in the model by taking the entire with

directly from the Ipswich River at RCHRES 43 

routing flows from the drainage area to the cana

the Ipswich River at RCHRES 48. The net flow 

Ipswich at RCHRES 48 is the same as if the SB

withdrawals were taken from the Ipswich River 

when withdrawals exceeded supply from the ca

tributing area. Simulated flows at RCHRES 43 

Ipswich River can differ from the actual flows, 

ever, because diversions do not account for the 

from the 4.7 mi2 drainage area of RCHRESs 44, 

and 47. Three outflow gates were specified for 

RCHRES 43: (1) withdrawals diverted to Wenh

Lake, (2) withdrawals diverted to Putnamville 

Reservoir, and (3) downstream routing. 

Three outflow gates were also specified f

Longham Reservoir (RCHRES 61): (1) withdra

diverted to Wenham Lake, (2) time series for ou

over the spillway into Miles River (RCHRES 6
Precipitation-Runoff M

(3) an FTABLE that specifies the volume-discharge 

characteristics of the reservoir and spillway. The third 

outflow gate is needed for this reach to route flow 

downstream for long-term simulations when timeseries of discharge over the spillway is unavailable. The 

time series of the reported discharge to Miles River are 

used when available because the spillway can be 

manually adjusted by three flashboards. 

Streamflow Depletion by Ground-Water Withdrawals

The effects of ground-water withdrawals on 

streamflow are calculated for each well with the 

program STRMDEPL described in Appendix A. 

STRMDEPL produces a time series of the total streamflow depletion in response to pumping, which consists 

of captured discharge or induced infiltration, or both. 

The time-varying streamflow depletion is calculated on 

the basis of the daily pumping rate, distance of the well 

from the stream, aquifer properties, and the hydraulic 

connection of the stream and the aquifer. Because 

STRMDEPL provides a direct measure of the effects of 

ground water withdrawals on streamflow, ground-water 

withdrawals are taken directly from reaches, which 

provide the spatial reference for the well or well field in 

the basin.

STRMDEPL variables for all the pumped wells 

in the Ipswich Basin were assigned a diffusivity 

(DIFFUS) of 10,000 ft2/d (based on aquifer properties 

reported by Baker and others,1964, and Samuel and 

others,1966) and a streambank material (IBANK) of 

zero to indicate no semi-impervious material is present. 

Other STRMDEPL variables depended on the distance 

of the well from the stream (given in table 4) and the 

initial pump rate. The pumping rates for individual 

wells are available in the WDM file (DSNs 2010 

through 2679).

Ground-water flow to a well is affected by many 

factors, including (1) transmissivity and storage properties of the aquifer, (2) types and relative position of 

boundary conditions, (3) withdrawal rates, and (4) transient conditions such as a change in recharge (Theis, 

1940). Detailed analyses of factors that affect flow to 

wells have been described by many authors and have 

been summarized by Reilly and Pollock (1993) and 

Franke and others (1998).

Although flow to a pumped well occurs in three 

dimensions, a simplified cross-section schematic of 

ground-water flow in a homogeneous aquifer to a 

stream illustrates the effects of pumping on streamflow 

(fig. 11). The ground-water flow system before 

development, in which the stream gains flow fro

ground-water discharge sustaining base flow in 

stream, is shown in figure 11A.

The hypothetical effects of a pumped wel

shown in figure 11B for the case of an initial wa

table surface similar to the undeveloped aquifer 

figure 11A. A cone of depression forms around 

pumped well; flow is diverted toward the well 

(forming a contributing area) resulting in a flow 

between the well and the stream. In this case, fl

the stream is decreased by the amount of groun

water flow diverted toward the well (captured b

flow). The size of the contributing area is affect

by the factors mentioned previously, but can als

include the influence of other ground-water 

withdrawals. 

The ground-water flow paths when the co

ing area extends below a wet stream channel an

head in the aquifer is below the head in the stre

shown in figure 11C. The downward gradient b

the stream and the aquifer induces infiltration of 

water into the aquifer. If the captured baseflow 

(fig. 11B) and induced infiltration (fig. 11C) are 

equilibrium with withdrawals, the water table s

will remain unchanged. 

When ground-water withdrawals exceed 

tured baseflow and induced infiltration, water is 

removed from ground-water storage, as shown 

figure 11D. The water-table surface continuous

lowers while the well is being pumped and is co

ered a transient or unsteady-state condition that 

cally occurs only during extended dry periods i

Ipswich River Basin. Changes in ground-water 

that result from withdrawals in excess captured 

flow and induced infiltration require special con

ation in the Ipswich Basin HSPF model to prese

mass balance of water.

Water Withdrawals in Excess of Streamflow

During extended periods of dry weather, 

water withdrawals can exceed streamflow in a r

reach. A comparison of actual withdrawals and 

withdrawals satisfied by streamflow in the HSP

lations in reaches above the South Middleton st

indicates that this condition occurs mostly in re

and 17 and mostly between June and Septembe

each year. These are headwater reaches with mu

pumped wells. Water withdrawals commonly ex

streamflow in these reaches by 50 percent or m

periods of several days or more during late sum
40 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

A. Ground-water flow paths under undeveloped conditions

Ground water 

discharges to stream

B. Ground-water flow paths with a pumped well 

Pumped well intercepts ground water 

that would have discharged to stream

D. Ground-water flow to a pumped well that intercepts ground water and 

 depletes ground-water storage (low recharge and dry stream condition)

Water taken from

storage

Dry

stream

C. Ground-water flow paths to a pumped well (low-water table condition) that

 intercepts ground water and induces infiltration from the steam

Pumped well intercepts ground water and

induces infiltration from flowing stream

Cone of depression enlarges (as compared to B.)

to satisfy demand by taking ground water

from storage

Cone of 

depression

Losing

stream

Figure 11. Ground-water flow paths illustrating captured recharge and induced infiltration 

in a hypothetical aquifer: (A) undeveloped aquifer, (B) pumped well with a high water table, 

(C) pumped well with a low-water table surface, and (D) changing storage when withdrawals 

exceed captured recharge and induced infiltration.
Precipitation-Runoff M

In other reaches, water withdrawals seldom exceed the 

streamflow. For example, water withdrawals in reach 8 

are about twice those in reach 1, but the cumulative 

withdrawals in the reach rarely exceeded streamflow in 

the reach during the calibration period, except in the 

summer of 1993. The reason for this difference is that 

the drainage area for reach 8 is about 4.5 times that of 

reach 1 and the runoff from this drainage area is normally sufficient to satisfy withdrawals in this reach. 

Table 9 summarizes the average difference between the 

actual withdrawals and the withdrawals satisfied by 

streamflow in the HSPF simulations for the 1989–93 

model calibration period. Table 9 also summarizes the 

number of days during which the withdrawals 

exceeded streamflow during this period.

When water withdrawals exceed the flow in the 

reach, an error was introduced in the hydrologic budget 

in the model with the original implementation of the 

STRMDEPL program. The error in the hydrologic 

budget in the HSPF simulations as a result of the deficit 

between actual withdrawals and the withdrawals satisfied by streamflow is generally minor, but can be appreciable during periods of low flow in some reaches. The 

error caused by the deficit between actual withdrawals 

and satisfied withdrawals will be exacerbated during 

periods of extended drought and cause deficits in 

reaches further downstream as flows decrease.

In nature, when ground-water withdrawals 

exceed streamflow, the excess demand is satisfied from 

ground-water storage, as previously described. Neither 

the HSPF model, or the STRMDEPL program, 

accounts for changes in ground-water storage that 

result from withdrawals in excess of streamflow. A 

‘Special Action’ was developed in the Ipswich River 

Basin HSPF model to correct for this inadequacy.

Special Actions can be introduced into th

model to increase its power and flexibility. The 

action (herein referred to as SA) developed as p

this study accounts for a running deficit betwee

actual withdrawals and the withdrawals satisfie

streamflow in the simulation. The SA then reple

this deficit when streamflow exceeds demands, 

maintaining the hydrologic mass balance of the 

over the simulation time period. In effect, reple

the deficit by the SA is analogous to recharging 

diminished ground water storage shown in figur

The SA tracks deficits for each reach with 

ground-water withdrawals. The following user-

variable quantities (UVQUAN’s) are used wher

nn is the reach number;

defnn is the current deficit in the reach;

cdemnn is the current time interval demand 

(withdrawal specified in the input time

series);

pdemnnis the previous time interval demand

(withdrawal specified for the previous

interval);

withnn is the simulated withdrawal that was

satisfied by streamflow for the previous

interval; and

deffrc is the fraction of deficit that must be

satisfied before streamflow can pass

through a reach.

The variables defnn and deffrc require a ta

address (UVNAMEs) for reference in action lin

UVNAMEs DEFnn and DEFFRC correspond to 

quantities defnn and deffrc, respectively. 

Table 9. Deficit between actual water withdrawals and the withdrawal satisfied by streamflow in the Hydrological Simu

Program-FORTRAN (HSPF) for Ipswich River reaches above the South Middleton station, Mass.,1989–93

[Percent: Percent difference between the actual water withdrawal and the satisfied withdrawal by streamflow. Days: Number of days when withdra

exceeded streamflow. No., number; ft3/s, cubic foot per second]

Reach 

No.

1989 1990 1991 1992 1993 Av

with

(

Percent Days Percent Days Percent Days Percent Days Percent Days 

1 11 43 8.3 26 17 56 4.5 28 31 88 

5 0 0 0 0 0 0 0 0 0 0 

8 .3 4 1.2 7 .5 5 0 1 15 52 

12 0 0 0 0 .1 1 0 0 13 48 

13 .5 6 .5 5 3.3 18 0 0 29 72 

17 18 54 15 36 21 53 7.8 34 50 101 

18 .5 1 0 0 1.2 3 1.0 2 .7 2 
42 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

DEFFRC represents the hydraulic connection 

between the stream and the aquifer (often referred to as 

leakance) by designating the fraction of the deficit satisfied before streamflow can pass downstream. In the 

Ipswich River Basin, DEFFRC was set to 1.0 for all 

reaches (the entire deficit must be replenished before 

any water is routed downstream) because the stream 

and the aquifer are believed to be well connected. In 

systems with a poor hydraulic connection, DEFFRC 

values less than 1.0 could be used, thus allowing some 

flow to pass downstream before the deficit is satisfied. 

A GENER operation is associated with each 

reach for which a deficit is computed. The value in 

each GENER corresponds to the deficit in the reach 

plus the current withdrawal in the reach. The deficit 

(defnn) is incremented each time step by adding the 

previous time interval's actual demand (pdemnn) minus 

the previous interval's satisfied withdrawal (withnn). If 

the deficit is greater than zero, the Operation Status 

Vector (OSV) variable K in the GENER operation is 

set equal to the deficit times the fraction allowed to 

pass through a reach (deffrc). The current demand 

(cdemnn) is then added to the value of K. If there is 

no deficit, K is set equal to zero. The NETWORK 

block passes the GENER K values to the time-series 

specified for the first outflow gate (OUTDGT 1) in 

reaches that have water withdrawals.

Initial simulations with the SA indicated model 

run times on a 400mHz Pentium II processor in excess 

of 2 hours as compared to run times of about 3 minutes 

with no SA when the model was run within GenScn. 

The SA causes a dramatic increase in run time because 

the model is required to work up and down the operation sequence to compute variables used in the SA. 

Subsequently, the SA was modified to decrease the 

main swapping by a factor of 24 by setting pdemnn

equal to the demand 25 hours ago and withnn equal to 

the actual withdrawal 24 hours ago. These values are 

then used to update the current deficit (defnn) as above, 

but with values that have a 24-hour lag time. The 

revised SA no longer uses the variable cdemnn, but 

rather reads the current outflow demand directly from 

the WDM file (targeted to the first outflow gateOUTDGT 1). The GENER K value is passed to 

OUTDGT 1 as above to produce the current outflow 

demand plus any deficit.

Figure 12 shows the actual withdrawal and the 

withdrawal satisfied by streamflow in the HSPF simulation in reach 1 for June through August 1991. In July, 

the withdrawal begins to exceed streamflow, and thus 

the withdrawal is only partly satisfied. During several 

periods the streamflow meets withdrawals, but 

flow does not exceed withdrawals until the end 

August. At this time, the deficit between actual 

drawal and the withdrawal that is satisfied by st

flow in the simulation is replenished over a 6-da

period.

Model Calibration

The Ipswich River Basin model was calib

for the period January 1, 1989 to December 31, 

using an hourly time step. The 1989–93 period 

used for calibration because water withdrawals 

be obtained or estimated for the major water-su

demands on the system during that time, and be

land-use data for 1991 were used to define the 

PERLNDs. The water-withdrawal data were ne

calibrate the model, and were not available for a

suppliers prior to 1989, at which time the suppl

were required to report their monthly water use 

State. Water-use data were available for years m

recent than 1993, but because land use has chan

rapidly in the basin since 1991, a calibration pe

centered on 1991 was believed to best represen

basin.

By calibrating to a period when water wi

als were quantified, the effects of these withdra

could be included in the simulation so that valu

hydrologic parameters would not be skewed. In 

this normalizes the simulated hydrograph so tha

values of hydrologic parameters are calibrated t

fected flows and hence reflect the natural hydro

DISCHARGE, IN CUBIC FEET PER SECOND

STREAM DISCHARGE

WATER WITHDRAWAL SATISIFIED

IN THE SIMULATION BY STREAMFLOW

ACTUAL WATER WITHDRAWAL

0

10

20

30

40

MAY JUNE JULY AU

15 31 15 30 15 31 

1991

Figure 12. Actual water withdrawals and the withdraw

satisfied by streamflow in the Hydrological Simulation 

Program-FORTRAN (HSPF) in reach 1 of the Ipswich 

Basin, Mass. for the period June 1, 1991 through Aug

1991.
Precipitation-Runoff M

response of the watershed. If the water withdrawals had 

been ignored in the calibration, then the hydrologic 

parameter values would have been skewed to include 

the effect of these withdrawals on flows.

Model parameter values were calculated from 

available spatial data to the extent possible. For example, the average slopes of the PERLNDs were calculated from the digital elevation data. Most parameter 

values could not be measured directly, however, and 

were derived by means of an iterative calibration process. HSPF modeling reports for the nearby Charles 

River watershed by Socolofsky (1997) and Munson 

(1998) provide initial values for some parameters that 

could not be measured. An iterative process (calibration) was then used to adjust the initial values to minimize the difference between simulated and observed 

flows. 

Flows at the South Middleton station and the 

Ipswich station, which correspond to RCHRESs 19 and 

56 (fig. 8), provided the principal data for calibration. 

The model was calibrated in accordance with g

lines by Donigian and others (1984) and Lumb 

others (1994a). This generally entailed adjustin

parameter values to improve the model fit for an

and seasonal budgets, then adjusting values to i

the model fit for daily flows while maintaining 

annual and seasonal budgets. Storm flow and sn

were not given detailed consideration because o

study time constraints and the primary purpose 

model for simulating low-flow periods.

Precipitation data at Reading, Mass. and 

averaged data from the 12-grid cell data provid

MBL (herein referred to as the centroid) were u

calibration because it was uncertain which data 

represented precipitation in the basin. Model-fit 

statistics are summarized in table 10 and genera

were similar for simulations made with precipit

from each source. The quality of the model fit w

examined by: (1) the coefficient of determinatio

of the linear regression between simulated and 

Table 10. Summary of annual, monthly, and daily model-fit statistics at South Middleton and Ipswich stations for Hydro

Simulation Program-FORTRAN (HSPF) simulations made with centroid and Reading precipitation data, Ipswich River 

Mass., 1989–93

[ft3/s, cubic feet per second; >, less than; %, percent]

Model-fit statistic

Annual Monthly Daily

Centroid Reading Centroid Reading Centroid Re

South Middleton station

Number of years, months, or days .............. 5 5 60 60 1,826 1,

Coefficient of determination (r2)................. .85 .99 .96 .95 .92 

Coefficient of model-fit efficiency .............. .72 .98 .92 .90 .85 

Standard error (ft3/s) ................................... 3.5 .8 2.0 2.2 .6 

Root mean square error (percent)................ 9.1 3.1 42 37 94 1

Percent time simulated value <10%............ 80 100 37 32 23 

Percent time simulated value <25%............ 100 100 65 63 51 

Median percent error................................... 2.4 2.4 -.1 8.2 -.4 

Minimum percent error ............................... -17 -1.7 -42 -41 -82 -

Maximum percent error .............................. 7.4 5.2 185 122 1,588 2,1

Ipswich station

Number of years, months, or days .............. 5 5 60 60 1,826 1,8

Coefficient of determination (r2)................. .92 .97 .98 .95 .94 

Coefficient of model-fit efficiency .............. .82 .92 .95 .90 .88 

Standard error (ft3/s) ................................... 6.6 4.7 4.3 6.6 1.6 

RMSE (percent) .......................................... 7.5 5.4 32 27 51 

Percent time simulated value <10%............ 80 100 38 43 24 

Percent time simulated value <25%............ 100 100 68 72 56 

Median percent error................................... -.4 1.6 -4.4 1.0 -4.2 

Minimum percent error ............................... -12 -8.3 -41 -48 -88 -

Maximum percent error .............................. 4.9 4.4 115 106 369 6
44 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

observed discharge; (2) the coefficient of 

model-fit efficiency, which measures the 

proportion of variance in the observed discharge explained by the simulated discharge 

(Nash and Sutcliffe, 1970). The coefficient 

of determination (r2) and the coefficient of 

model-fit efficiency are similar because both 

provide a measure of the variation in the 

simulated value explained by the observed 

value. The coefficient of model-fit 

efficiency, however, provides a more rigorous evaluation of the fit quality than does 

the r2 because the model-fit efficiency measures the magnitude of the differences 

between simulated and observed values, 

whereas the r2 measures the difference 

between mean values (Duncker and 

Melching, 1998). In cases in which the 

observed values and model residuals 

are normally distributed, the value of the 

r

2 and the model-fit efficiency should be 

equal. The difference between simulated 

and observed discharges were also reported 

as the (1) standard error, in cubic feet per 

second; (2) root mean square error, in percent; (3) percent of time differences were 

within 10 percent, and (4) percent of time differences 

were within 25 percent; (5) median percent error, 

(6) minimum percent error, and (7) maximum percent 

error.

Mean Annual Discharge

Observed and simulated mean annual discharge 

at the South Middleton and Ipswich stations for simulations made with centroid and Reading precipitation 

data for the 1989–93 calibration period are summarized 

in table 11. Mean annual discharge at the South 

Middleton station are undersimulated on average by 

2.1 percent for simulations made with centroid precipitation data and oversimulated by 2.2 percent for simulations made with Reading precipitation data. Mean 

annual discharge at the Ipswich station are undersimulated on average by 3.1 percent for simulations made 

with centroid precipitation data and oversimulated on 

average by about 1.1 percent for simulations made with 

Reading precipitation data. Donigian and others 

suggest that simulated total water budgets withi

percent of the observed represent a very good m

Simulated versus observed mean annual d

charge is shown in figure 13. The linear regress

(fig. 13) closely matches the line of equality an

coefficient of model-fit efficiency indicates that 

model explained 92 percent, or more, of the vari

the mean annual discharge for simulations mad

the Reading precipitation data at both sites. The 

cient of model-fit efficiency indicates that the m

explained 72 percent, or more, of the variation i

mean annual discharge for simulations made w

centroid precipitation data at both sites. The ove

model-fit statistics (table 10) and regression fit (

are somewhat better for simulations with the Re

precipitation than with the centroid precipitatio

both stations, largely because of the simulation

the centroid data are undersimulated by more th

percent at both stations in 1990 (table 11). The 

annual precipitation in 1990 with the centroid d

Table 11. Observed and simulated annual discharge at South Mid

and Ipswich stations for Hydrological Simulation Program-FORTR

(HSPF) simulations made with centroid and Reading precipitation 

Ipswich River Basin, Mass., 1989–93

[Discharge values in cubic foot per second. Precipitation values in inches]

Year Observed

discharge

Centroid Reading

Simulated

discharge

Percent

difference

Precipitation

Simulated

discharge

Percent

difference

South Middleton station

1989 47 48 2.4 44.2 48 2.4 

1990 83 69 -17 49.3 85 1.5 

1991 59 63 6.4 47.6 58 -1.7 

1992 57 54 -6.1 43.8 59 3.2 

1993 76 81 7.4 44.9 80 5.2 

Mean 64 63 -2.1 46.9 66 2.2 

Ipswich station

1989 126 133 4.9 44.2 133 5.0 

1990 212 186 -12 49.3 229 6.9 

1991 164 163 -.4 47.6 151 -8.3 

1992 158 143 -9.5 43.8 157 -.8 

1993 214 223 3.9 44.9 219 1.6 

Mean 175 170 -3.1 46.9 178 1.1 
Precipitation-Runoff M

about 10 percent less than the Reading data, thus the 

centroid data appears to under-represent precipitation 

in the basin during this year. 

Monthly Mean Discharge and 

Seasonal Water Budgets

Observed monthly mean discharges ranged from 

lows of 1.0 and 8.1 ft3/s (August 1993) to highs of 343 

and 1,070 ft3/s (April 1993) at the South Middleton and 

Ipswich stations, respectively. Simulated discharge for 

the same periods ranged from lows of 1.0 and 5.0 ft3/s 

to highs of 347 and 974 ft3/s at the South Middleton 

and Ipswich stations, respectively, for simulations 

made with the centroid precipitation data. Simulated 

monthly mean discharges for the same periods made 

with the Reading precipitation data ranged from lows 

of 1.3 and 5.9 ft3/s to highs of 297 and 833 ft3/s at the 

South Middleton and Ipswich stations, respectively. 

The coefficient of model-fit efficiency indicates that at 

a minimum the model explained 90 percent of the variation in the observed monthly flows at both stations 

when the flows are simulated with either set of precipitation data. Regression lines indicate little bias in the 

simulated monthly mean discharge (fig. 14); however, 

the regression fit is slightly better for simulations made 

with the centroid precipitation data than for simulations 

made with the Reading precipitation data because the 

regression line is leveraged by an outlier (high runoff in 

April 1993) that was better simulated with the centroid 

data than the Reading data. 

A seasonal bias was observed during cali

of flows at both the South Middleton and Ipswi

tions (fig. 15 dashed line). This appears to refle

seasonal bias reported in the Jensen-Haise PET 

tations by Winter and others (1995), who comp

methods for calculating free-surface evaporatio

small lake in Minnesota. They report that the Je

Haise method, and other equations with a solar 

tion component, overestimate evaporation durin

through July and underestimate evaporation in 

September in comparison to values computed fr

energy budget. Winter and others (1995) also re

a large scatter in the Jensen-Haise PET comput

values for August. Leavesley and others (1983) 

that the Jensen-Haise and Hamond methods ten

underestimate PET during the winter period. PE

values computed by equations that are based on 

radiation data tend to exhibit a seasonal bias be

they do not account for latent heat in the water 

this results in overestimated PET values during 

spring and early summer period and underestim

PET values during the early fall through early w

period. The Ipswich River Basin model simulat

charges made with unadjusted Jensen-Haise PE

values reflect this bias by undersimulating disch

in the spring and early summer and oversimulat

discharge in the fall and winter.

Initial Jenkins-Haise PET values were ad

empirically during the calibration by modifying 

monthly variable coefficient (CTS) to minimize 

sonal bias (fig. 15 solid line). These changes in t

SIMULATED MEAN ANNUAL DISCHARGE,

IN CUBIC FEET PER SECOND

40 60 80 100

A. SOUTH MIDDLETON STATION

40

60

80

100

OBSERVED MEAN ANNUAL DISCHARGE, IN CUBIC FEET PER SECOND

SIMULATION WITH

 CENTROID DATA 

 REGRESSION FIT

SIMULATION WITH

 READING DATA

 AND REGRESSION 

LINE OF EQUALITY 

B. IPSWICH STATION

EXPLANATION

100

150

200

250

100 150 200 250

Figure 13. Relation of simulated mean annual discharge to observed for simulations made with centroid and Read

precipitation data for the Ipswich River, Mass., at (A) South Middleton station, and (B) Ipswich station, 1989–93.
46 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

A. SOUTH MIDDLETON STATION

B. IPSWICH STATION

0

100

200

300

400

0 100 200 300 400

0

400

800

1,200

0 400 800 1,200

MONTHLY RUNOFF

SIMULATED MEAN MONTHLY DISCHARGE,

IN CUBIC FEET PER SECOND

OBSERVED MEAN MONTHLY DISCHARGE,

IN CUBIC FEET PER SECOND

Centroid Reading

REGRESSION 

LINE OF EQUA

0

400

800

1,200

0 400 800 1,200

0

100

200

300

400

0 100 200 300 400

EXPLANATION

values are within guidelines described in METCMP 

(Lumb and Kittle, 1995). Figure 15 indicates that most 

of the seasonal bias at both stations was removed by 

adjusting the PET data. The percent mean monthly 

discharge error departs from the zero line for several 

periods, but these departures are largely due to outliers. 

The coefficient of model-fit efficiency indicates that 

at a minimum the model explained 75 percent of the 

seasonal flow variability for simulations made with 

the centroid precipitation data. The coefficient of 

model-fit efficiency values for monthly seasonal discharges were generally less for simulations made with 

Reading precipitation data than for simulations 

with centroid data (table 12). Typically, a seaso

model-fit efficiency with a low value for simula

made with one precipitation source had a substa

higher model-fit efficiency for the same season 

simulations made with the other precipitation so

Daily Flow

Observed daily mean discharges for the c

tion period ranged from 0.3 ft3/s (August 29, 19

670 ft3/s (April 2, 1993) at the South Middleton 

and from 2.5 ft3/s (September 4, 1993) to 2,490 

Figure 14. Relation of simulated monthly discharge to observed for simulations made with centroid and Reading 

precipitation data for the Ipswich River, Mass. at (A) South Middleton station, and (B) Ipswich station, 1989–93.
Precipitation-Runoff M

(April 2, 1993) at the Ipswich station (fig. 16). Simulated daily mean discharges for the same period made 

with the centroid precipitation data ranged from 0.3 

ft3/s to 657 ft3/s at the South Middleton station, and 

from 2.8 ft3/s to 1,710 ft3/s at the Ipswich station. Simulated discharges made with the Reading precipitation 

data ranged from 0.3 ft3/ to 580 ft3/s at South Middleton station and from 3.5 ft3/s to 1,500 ft3/s at the 

Ipswich station. The coefficient of model-fit efficiency 

indicated that at a minimum, the model explained 85 

percent of the variation in the observed daily mean discharge at both stations for simulations made with the 

centroid precipitation data. The coefficient of model-fit 

efficiency was slightly less for simulations made with 

the Reading precipitation data (table 10). 

In general, the simulated hydrographs at 

South Middleton and Ipswich stations parallel t

observed hydrographs over a wide range of flow 

tions and seasons (figure 17A and 17B) for simu

made with the centroid precipitation data. The h

graphs for simulations made with the Reading p

tation data were similar to those for simulations 

with the centroid precipitation data and, therefo

were not included in figure 17. The simulated s

hydrograph recession generally matches the ob

hydrograph recession; this match indicates that 

in the Ipswich River Basin, and physical proper

that affect storage, are reasonably represented i

the model.

A. SOUTH MIDDLETON STATION

MONTH

Jan Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

B. IPSWICH STATION

PERCENT ERROR

1989

1990

1991

1992

1993

MEAN MONTHLY 

 DISCHARGE

MEAN MONTHLY

 DISCHARGE PRIOR TO

 ADJUSTING POTENTIAL

 EVAPOTRANSPIRATION

 (PET) 

EXPLANATION

-100

-50

0

50

100

150

200

-100

-50

0

50

100

150

200

Figure 15. Percent error between simulated flow made with the centroid precipitation data and observed flows 

for the Ipswich River, Mass., at the (A) South Middleton and (B) Ipswich stations by month, before and after 

adjusting evapotranspiration rates for seasonal bias, 1989–93.
48 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Differences between simulated and observed 

flows are shown in figure 18 as a function of time and 

in figure 19 as a function of discharge. These figures 

were developed from results of simulations made with 

the centroid precipitation data. Figure 18 indicates that 

the largest errors (at both the South Middleton and 

Ipswich stations) are during the winter period, probably because of differences between actual and simulated snowpack buildup and melt. This is underscored 

by the errors shown as a function of the magnitude of 

flow (fig. 19), which indicates that the largest errors are 

during the highest flows. The annual peak discharge is 

often during the spring and usually includes snowmelt 

runoff. A comparison of the simulated and observed 

hydrographs at the Ipswich station, and the simulated 

snowpack water (fig. 20) during the peak of record for 

the calibration period (early April 1993) sugges

water was retained in the snowpack longer and 

released more rapidly than simulated; this increa

simulated discharge earlier than observed which 

resulted in a smaller simulated peak discharge t

observed. 

Flow Duration

Flow-duration curves show the percentag

time a specified discharge is equaled or exceede

reflect the combined effects of climate, topograp

hydrogeologic conditions on the distribution of 

magnitude through time (Searcy, 1959). A comp

of flow-duration curves computed from observe

daily discharges at the South Middleton and Ips

stations for the 1989-93 calibration period with 

Table 12. Summary of seasonal model-fit statistics at South Middleton and Ipswich stations for Hydrological Simulatio

Program-FORTRAN (HSPF) simulations made with centroid and Reading precipitation data, Ipswich River Basin, Mas

1989–93 

[ft3/s, cubic foot per second; >, less than; %, percent]

Model-fit statistic

Winter Spring Summer Fall

Centroid Reading Centroid Reading Centroid Reading Centroid R

South Middleton station

Number of months................................ 15 15 15 15 15 15 15 

Coefficient of determination (r2) .......... .96 .96 .97 .93 .90 .94 .93 

Coefficient of model-fit efficiency........ .91 .89 .94 .86 .76 .52 .75 

Standard error (ft3/s)............................. 2.9 3.1 4.7 7.0 2.3 2.7 5.0 

Root mean square error (percent) ......... 11 21 19 25 79 67 43 

Percent time simulated value <10% ..... 47 47 47 40 20 7 27 

Percent time simulated value <25% ..... 80 80 87 80 47 27 47 

Median percent error ............................ -.1 4.7 -1.6 -.1 14 39 -8.9 

Minimum percent error......................... -32 -26 -21 -42 -28 -6 -41 

Maximum percent error........................ 33 43 41 52 179 122 86 

Ipswich station

Number of months................................ 15 15 15 15 15 15 15 

Coefficient of determination (r2) .......... .96 .96 .97 .92 .94 .90 .97 

Coefficient of model-fit efficiency........ .92 .87 .93 .84 .88 .58 .93 

Standard error (ft3/s)............................. 7.4 8.1 15 24 4.6 8.0 5.3 

Root mean square error (percent) ......... 39 35 38 26 36 37 27 

Percent time simulated value <10% ..... 53 47 33 40 33 40 33 

Percent time simulated value <25% ..... 73 67 73 73 53 60 73 

Median percent error ............................ 1.5 7.7 -11 -3.0 -4.4 6.4 -4.8 

Minimum percent error......................... -27 -42 -31 -48 -38 -27 -41 

Maximum percent error........................ 101 73 113 46 70 106 53 
Precipitation-Runoff M

1 10 100 1,000 10,000

1

10

100

1,000

10,000

1 10 100 1,000 10,000

0.1

10

1,000

1

100

OBSERVED DISCHARGE, IN CUBIC FEET PER SECOND

DAILY DISCHARGE

SIMULATED DISCHARGE, IN CUBIC FEET PER SECOND

CENTROID READING

A. SOUTH MIDDLETON STATION

B. IPSWICH STATION

LINE OF EQUALITY

from simulated mean daily discharges made with either 

set of precipitation data indicates a similar magnitude 

and frequency of daily flows (fig. 21). The flow frequency curve of simulated daily discharges deviates 

from the curve of the observed discharges for flows 

greater than 1,500 ft3/s (0.5 percent probability of 

being equaled or exceeded) at the Ipswich station for 

simulations made with either precipitation data; this 

reflects the difference in the timing of snowmelt runoff 

as previously mentioned. 

Low Flows

Simulated and observed flows that have 

exceedence probabilities of 98 percent and 90 p

or more at the South Middleton and Ipswich sta

were compared. These are flows less than about 

and 6 ft3/s for flows with a 98-percent exceeden

probability, and 7 and 22 ft3/s at the 90-percent 

exceedence probability at the South Middleton 

Ipswich stations, respectively (flow duration cu

fig. 21). The computed error statistics between 

lated and observed flows within the 98- and 90-

Figure 16. Relation of simulated daily mean discharge to observed for simulations made 

with centroid and Reading precipitation data for the (A) South Middleton, and (B) Ipswich 

stations, Ipswich River, Mass., 1989–93.
50 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

A. SOUTH MIDDLETON STATION

B. IPSWICH STATION

OBSERVED

SIMULATED

0.1

1

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

1

10

100

1,000

10,000

CENTROID DAILY PRECIPITATION

J FMAMJ J ASOND J FMAMJ J ASOND J FMAMJ J ASOND J FMAMJ J ASOND J FMAMJ J AS

1989 1990 1991 1992 1993

0

0.1

0.2

PRECIPITAION,

IN INCHES

probability range are given in table 13 for simulations 

made with the centroid and Reading precipitation data. 

Note that some values, such as the root mean square 

error, are reported in cubic feet per second instead of 

percent as reported previously. Model-fit statistics 

reported as a percent can be a poor indicator of the 

quality of the fit because a small absolute differ

can be a large difference when expressed as a p

age of the low-flow value. In general, the mode

simulations made with precipitation data from t

troid are comparable to simulations made with 

Reading precipitation data. 

Figure 17. Simulated and observed daily-mean-discharge hydrographs for simulations made with centroid precipitat

data at the (A) South Middleton, and (B) Ipswich stations, Ipswich River, Mass., 1989–93.
Precipitation-Runoff M

SIMULATED MINUS OBSERVED DAILY DISCHARGE, 

IN CUBIC FEET PER SECOND

-800

-600

-400

-200

0

200

400

600

800

J FMAMJ J ASOND J FMAMJ J ASON D J FMAMJ J A SOND J FMAMJ J ASOND J FMAMJ J AS

1989 1990 1991 1992 1993

-300

-200

-100

0

100

200

300

A. SOUTH MIDDLETON STATION

B. IPSWICH STATION

The coefficients of determination and model-fit 

efficiency have decreased considerably from the model 

fit for all daily flows. This decrease is largely because 

of the scatter between simulated and observed discharges at this range in flow, particularly at the South 

Middleton station (fig. 16). Table 13 indicates that the 

model fit improves considerably for flows at the 90-

percent exceedence probability compared to those at 

the 98-percent exceedence probability. The model fit 

for simulated low flows is also somewhat better at the 

Ipswich station than at the South Middleton station. In 

general, the standard error and root mean square errors 

are small and within plus or minus the flow magnitude 

at the given exceedence probability at both sites.

For the 1989–93 period, the median obse

flow at or below the 98-percent exceedence prob

was 0.6 ft3/s at the South Middleton station and 

5.4 ft3/sec at the Ipswich station; the median ob

flow at or below the 90-percent exceedence prob

was 1.8 ft3/s at the South Middleton station and 

at the Ipswich station. For the same period that 

observed flows were at or below the 98-percent 

exceedence probability, the median simulated fl

made with either set of precipitation data was 1

at the South Middleton station and 5.4 ft3/s at th

Ipswich station. For the same period that the ob

flows were at or below the 90-percent exceeden

probability, the median simulated flow made wi

either precipitation data was 2.5 ft3/s at the Sou

Figure 18. Difference between simulated and observed daily mean discharges as a function of time at the (A) South 

Middleton, and (B) Ipswich stations, Ipswich River Mass., 1989–93.
52 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

-800

-600

-400

-200

0

200

400

600

800

1 10 100 1,000 

 SIMULATED MINUS OBSERVED DAILY DISCHARGE,

 IN CUBIC FEET PER SECOND -300

-200

-100

0

100

200

300

OBSERVED DAILY DISCHARGE, IN CUBIC FEET PER SECOND

A. SOUTH MIDDLETON STATION

B. IPSWICH STATION

Middleton station and 11 ft3/s at the Ipswich station. 

At the South Middleton station, the median simulated 

flow during the time the observed flows were at or 

below the 90- and 98-percent exceedence probabilities 

were about 50 percent larger than the observed median 

flows. At the Ipswich station, the median simulated 

flows during the time the observed flows were at 

or below the 90- and 98-percent exceedence 

probabilities were the same as the observed median 

discharges. 

Miscellaneous Discharge Measurements

Miscellaneous discharge measurements h

been made at a number of locations in the Ipsw

River Basin for the river habitat assessment stud

(David Armstrong, USGS, person. commun., 19

Discharge measurements were made at only Fis

Brook at Lockwood Lane near Boxford (fig. 8, 

01101740), which is represented by reach numb

during the calibration period. Fish Brook near B

Figure 19. Difference between simulated and observed daily mean discharges as a function of observed discharge at 

(A) South Middleton, and (B) Ipswich stations, Ipswich River, Mass., 1989–93.
Precipitation-Runoff M

SNOWPACK WATER EQUIVALENT, IN INCHES

SIMULATED SNOWPACK WATER

0

1

2

3

4

5

6

7

8

OBSERVED DISCHARGE

SIMULATED DISCHARGE

MEAN DAILY DISCHARGE, 

IN CUBIC FEET PER SECOND

0

500

1,000

1,500

2,000

2,500

3,000

PRECIPITATION,

IN INCHES

0.0

1.0

2.0

Melting Point

MEAN DAILY AIR TEMPERATURE

5 10 15 20 25

FEBRUARY

28 5 10

MARCH

15 20 25 31 5 10

APRIL

15 20 25

1993

drains a 15.5 mi2 area that is 40 percent forest and 23 

percent wetland. Three discharge measurements were 

made at this site in July 1993. Figure 22 indicates that 

the simulated discharges are slightly greater than measured discharges; however, the simulations appear reasonable given the fact that no direct calibration was 

performed for this location. Simulated flows made with 

either set of precipitation data appear to closely match 

the measured flows at the stations during this time. 

Summary of the Differences Between 

Simulations with Reading and 

Centroid Precipitation Data

A number of factors affect the match between the 

simulated and observed discharge, especially the representativeness of precipitation data over the basin. 

Although results for simulations made separately with 

the Reading and centroid precipitation data are 

simulations made with one data set improved so

measures of the model fit, but caused others to 

In general, simulations made with the Re

data appear to represent the precipitation in the 

part of the basin (to the South Middleton station

than the simulations made with the centroid dat

versely, simulations made with the centroid data 

to represent precipitation in the lower basin (to 

Ipswich station) better than simulations made w

Reading data. These differences in the model fi

result from use of different precipitation data se

expected because of the spatial position of the s

data in the basin (fig. 1). The small gains in the 

ness of the model fit probably do not warrant us

arate precipitation data for different parts of the 

because this would double the number of HRUs 

there are no long-term differences between thes

Figure 20. Observed and simulated daily mean discharge at the Ipswich station for simulations made with the centroid 

precipitation, air temperature, and simulated snowpack water for the Ipswich River Basin, Mass., February through April 
54 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Simulation results made with the two precipitation data sets do not clearly indicate that one precipitation station better represents precipitation over the 

entire basin than the other. Daily flows simulated with 

the centroid precipitation data were slightly “better”

overall than daily flows simulated with the Reading 

precipitation data and, therefore, were used for all 

scenario simulations.

Sensitivity Analysis

 A sensitivity analysis provides an indicat

the effects of changes in the parameter values re

senting watershed properties on the response of 

model-simulated values. An iterative process, w

the value of a given parameter is varied while a

parameters are held constant, indicates the degr

which that parameter can affect simulation resu

The sensitivity analysis applied constant change

parameter values equally over seasons and amo

hydrologic response units. A discussion of the fl

components and evapotranspiration losses simul

the Ipswich River Basin model for each of the h

logical response units is given below. The relati

differences between HRUs provide an understa

of the model response (sensitivity) to changes i

parameter values. 

Response of Pervious (PERLNDs) 

and Impervious (IMPLNDs) 

Land Segments

The hydrologic response of pervious and 

vious land segments are important to understan

effect that HRUs have on the model results. Exa

tion of flow components and evapotranspiration 

for each HRU indicate the predominant sources 

losses of water in the model and which model p

ters will be most influential in the simulation pr

Flow components and evapotranspiration losses 

PERLNDs and IMPLNDs are plotted in figure 

(1) the mean annual water budget during 1989–

(2) a wet month (April 1993), and (3) a dry mon

(August 1993). Flow components (discharge to 

in the Ipswich River Basin model) are shown as 

above the zero line and evapotranspiration losse

shown as bars below the zero line. 

Surface runoff from an IMPLND is equal 

moisture supply minus a small evaporation loss 

interception storage. Although the total runoff p

area from an IMPLND is larger than a PERLND 

(which has evapotranspiration losses from subs

storages), the timing and magnitude of runoff fr

IMPLND is not moderated by subsurface storag

flow from a PERLND. Thus, IMPLNDs produc

storm flows and smaller low flows then a PERL

0.1

1

10

100

1,000

DISCHARGE, IN CUBIC FEET PER SECOND

1

10

100

1,000

10,000

PERCENT CHANCE DISCHARGE EXCEEDED

A. SOUTH MIDDLETON STATION

B. IPSWICH STATION

EXPLANATION

0.5 1 2 5 10 30 50 70 90 95 98 99.5

OBSERVED

SIMULATED 

0.5 1 2 5 10 30 50 70 90 95 98 99.5

Centroid data 

Reading data

Figure 21. Flow-duration curves for observed and 

simulated daily mean discharges for simulations 

made with the centroid and Reading precipitation 

data for the (A) South Middleton, and (B) Ipswich 

stations, Ipswich River, Mass., 1989–93.
Precipitation-Runoff M

No surface runoff (as a percent of the me

annual runoff or during a wet or dry month) wa

cated from PERLNDs representing sand and gr

(nos. 1 through 6). Mean annual surface runoff 

percent of total runoff from PERLNDs represen

(nos. 8 through 13) ranged from 1.5 to 5.9 perc

was greatest in high-density residential areas (n

and 13). Surface runoff represented less than 1 

of the total runoff from PERLNDs representing 

vium (nos. 14 and 15) and commercial areas (n

Surface runoff represented 4 percent or less of t

runoff during the wet month (April 1993) for 

PERLNDs representing till (nos. 8 through 13) 

commercial areas (no. 7) and no surface runoff 

cated for any PERLND during the dry month (A

1993).

Table 13. Summary of low-flow model-fit statistics at the South Middelton and Ipswich stations for Hydrological Simula

Program-FORTRAN (HSPF) simulations made with centroid and Reading precipitation data, Ipswich River Basin, Mas

1989–93

[ft3/s, cubic foot per second; <, less than; %, percent]

Model-fit statistic

98-Percent exceedence probability1

1Discharges less then or equal to: 0.7 ft3/s at the South Middleton station, 6.0 ft3/s at the Ipswich station.

90-Percent exceedence prob

2Discharges less then or equal to: 7.0 ft3/s at the South Middleton station, 22 ft3/s at the Ipswich station.

Centroid Reading Centroid Read

South Middleton station

Number of days .................................................. 41 41 229 229

Coefficient of determination (r2) ........................ -.11 -.10 .54 

Coefficient of model-fit efficiency...................... -169 -323 -5.4 -3

Standard error (ft3/s)........................................... .20 1.7 4.5 3

Root mean square error (ft3/s) ............................ 1.5 2.1 4.9 4

Percent time simulated value <10% ................... 5 7 9 10

Percent time simulated value <25% ................... 10 10 21 23

Median error (ft3/s)............................................. .50 .5 .4 

Minimum error (ft3/s)......................................... -.3 -.3 -5.0 -4

Maximum error (ft3/s) ........................................ 5.2 6.4 28 25

Ipswich station

Number of days .................................................. 75 75 222 222

Coefficient of determination (r2) ........................ .42 .61 .60 

Coefficient of model-fit efficiency...................... -4.9 -2.2 -2.0 -2

Standard error (ft3/s)........................................... 3.0 .70 9.4 

Root mean square error (ft3/s) ............................ 3.3 2.4 9.9 11

Percent time simulated value <10% ................... 21 27 18 21

Percent time simulated value <25% ................... 52 49 43 49

Median error (ft3/s)............................................. .1 1.1 -1.0 1

Minimum error (ft3/s)......................................... -2.9 -2.1 -17 -16

Maximum error (ft3/s) ........................................ 11. 8.3 45 55

0

5

10

15

20

CENTROID PRECIPITATION DATA

READING PRECIPITATION DATA

SIMULATED DISCHARGE

MEASURED DISCHARGE

1 5 10 15 20 25 30 5 10 15 20 25 30

DISCHARGE, IN CUBIC 

FEET PER SECOND

FISH BROOK AT BOXFORD, MASS (MODEL REACH 39)

June 1993 July 1993

Figure 22. Discharge simulated with centroid and Reading 

precipitation data and instantaneous discharge 

measurements made at Fish Brook near Boxford, Mass., 

July 1993.
56 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Ground-water 

Lower-zone 

Upper-zone 

Surface 

Surface runoff

Interflow

Baseflow

- EVAPOTRANSPIRA

 LOSSES—

+ DISCHARGE TO 

REACHES—

EXPLANAT

0

-8

-6

-4

-2

0

2

4

6

8

C. DRY MONTH WATER BUDGET - AUGUST 1993

B. WET MONTH WATER BUDGET - APRIL 1993

-10

-5

0

5

10

15

20

INCHES

On public water 

and onsite septic

Commercial

Forest

Open

Low density

Low Density

High density

High Density

Forest

Open

HYDROLOGIC RESPONSE UNIT 

On public water 

and onsite septic

Overlying

alluvial

Impervious areas

(IMPLNDs)

Overlying 

till and bedrock

Overlying 

sand and gravel

Forest

Open

Low density

Low Density

High density

High Density

Residential

Commercial

Pervious areas (PERLNDs)

Residential Residential

-50

-40

-30

-20

-10

0

10

20

30

40

50

A. MEAN ANNUAL WATER BUDGETS

Figure 23. Runoff as surface-flow, interflow, and base-flow, and evapotranspiration losses from surface storage, uppe

storage, lower-zone storage, and ground-water storage from each hydrologic response unit for: (A) mean annual water 

(B) wet-month water budget for April 1993, and (C) dry-month water budget for August 1993, Ipswich River Basin, Mas
Precipitation-Runoff M

Mean annual interflow as a percent of total 

runoff ranged from 2 to 11 percent in PERLNDs 

representing sand and gravel (nos. 1 through 6), 46 

to 58 percent in PERLNDs representing till (nos. 8 

through 13), and 25 to 34 percent in PERLNDs 

representing alluvium (nos. 14 and 15). Interflow 

was generally smallest in PERLNDs representing 

forest (nos. 1, 8, and 14). During the wet month 

(April 1993), interflow as a percent of total runoff 

ranged from 14 to 33 percent in PERLNDs 

representing sand and gravel, 68 to 76 percent in 

PERLNDs representing till, and 55 to 60 percent in 

PERLNDs representing alluvium. It should be noted 

that some differences in runoff during this period result 

from uneven moisture supply distribution from 

snowpack water carried over from the previous month. 

During the dry month (August 1993), interflow as a 

percent of total runoff was less than 1 percent in 

PERLNDs representing sand and gravel, 2.6 to 6.3 

percent in PERLNDs representing till, and 0 to 2.2 

percent in PERLNDs representing alluvium.

Mean annual baseflow as a percent of total runoff 

ranged from 89 to 98 percent in PERLNDs representing sand and gravel (nos. 1 through 6), 36 to 52 percent 

in PERLNDs representing till (nos. 8 through 13), 

and 65 to 74 percent in PERLNDs representing alluvium (nos. 14 and 15). During the wet month (April 

1993), baseflow as a percent of total runoff ranged 

from 67 to 86 percent in PERLNDs representing sand 

and gravel, 21 to 32 percent in PERLNDs representing 

till, and 40 to 45 percent in PERLNDs representing 

alluvium. During the dry month (August 1993), baseflow represented nearly the entire runoff from all 

PERLNDs. 

Mean annual evapotranspiration (ET) losses are 

relatively evenly distributed among PERLNDs. ET 

losses from the surface, and upper- and lower-zone 

storage represent about 24, 30, and 45 percent of the 

total mean annual ET loss, respectively. Active ground 

water ET is less than 1 percent of the total annual ET 

from any PERLND. During the wet month (April 

1993), ET losses are primarily from upper-zone storage 

(averages 68 percent of the total ET loss) and surface 

ET (averages 25 percent of the total ET loss). During 

the dry month (August 1993), ET losses are primarily 

from the lower-zone storage (averages 70 perce

the total ET) and surface ET (averages 24 perce

the total ET). 

Several general findings can be drawn fro

comparison. Surface runoff is generated primar

IMPLNDs and to a small extent by PERLNDs s

ing areas of till (nos. 8 through 13). Surface run

from these till PERLNDs generally occurs duri

ods of heavy precipitation or snowmelt, or both

the winter and spring, when evapotranspiration 

are small and subsurface storage is at or near sa

tion. Surface runoff generally represents a smal

ponent of the hydrologic budget; thus, paramete

affect surface runoff have little effect on the unc

of the model predictions. 

Interflow is a major runoff component fro

areas overlying till and this component become

larger portion of the total runoff during wet mo

Model parameters that affect interflow will hav

greater effect in PERLNDs representing till (no

through 13) than in other PERLNDs and interfl

model parameters will have a larger effect on ru

during wet months than dry months. Baseflow i

major runoff component from areas of sand and 

and is the dominant runoff component during d

months for all PERLNDs. Model parameters th

affect baseflow will have a greater effect on PER

representing sand and gravel (nos. 1 through 6) 

in other PERLNDs, and baseflow model param

will be the dominant model parameters during p

of low flow. 

ET losses are primarily from upper-zone 

storage during the non-growing (cooler) month

from lower-zone storage during the growing sea

Model parameters that affect the amount of upp

zone storage and the rate of ET loss from the up

zone will have a greater effect in the cooler mon

than during the growing season. Conversely, mo

parameters that affect the amount of lower-zone 

storage and the rate of ET loss from the lower zo

have a greater effect in the growing season than 

the non-growing season.
58 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Parameter Values

Model sensitivity to eleven PERLND parameters, and storage associated with wetland reaches, 

(tables 14 and 15) were examined by sequentially 

doubling and then halving the calibrated parameter 

or storage values and measuring the effect of these 

changes on the simulated (1) total runoff volume, 

(2) high- and low-flow distribution, (3) seasonal 

and summer runoff, (4) peak stormflow, and 

(5) proportion of interflow and surface runoff. These 

flow characteristics were examined using HSPEXP 

(Lumb and others, 1994a); however, the inflow from 

septic effluent was redirected as lateral surface inflow 

(LSURLI) due to limitations of HSPF version 11. 

The special action (SA) component of the Ipswich 

River Basin model, which accounts for deficits 

between water withdrawals and the withdrawal that 

was satisfied by streamflow, was not used for these 

simulations. Tests indicated that flow characteristics 

generated at the South Middleton and Ipswich 

stations did not appreciably change when the SA 

was included in the simulations used for sensitivity 

testing.

Several parameters (IRC, LZETP, and AGWRC) 

could not be doubled because they would exceed the 

model’s maximum allowed value; for these parameters 

the upper values were set at the maximum allowed 

value or by half the difference between the base value 

and the maximum allowed value, depending on which 

value best reflected the change in the value relative to 

other PERLNDs. The effect of altering the calibrated 

values is expressed in table 14 as the relative sensitivity 

(RS), in percent, and in table 15 as the absolute error 

(AE) relative to the observed value. The sensitivity 

values are calculated from a single flow characteristic 

value generated by the HSPEXP for the entire calibration period. The relative sensitivity (RS) is computed 

using the following equation:

, (1)

where

V is the value of the flow characteristic (inches),

P is the parameter value;

b is the calibrated value, and

a is the altered sensitivity value. 

The absolute error is calculated by the followin

equation:

, 

where

Vo is the value of the observed flow charac

(inches); and

Vs is the value of the simulated flow charac

(inches).

The AGWRC variable, the rate that water 

released from active ground-water storage, is cl

its maximum permitted value. As a result, even 

change in the flow characteristic from an increa

AGWRC (table 14) produces a large change in 

value because the denominator in the RS equati

small. IRC, the interflow recession constant, is 

highly sensitive to increases in its value for sim

reasons. 

In general, the relative sensitivity analysi

cates that the most influential model parameters 

those that affect ground water (AGWRC and K

and to a lesser extent, parameters that affect int

(INTFLW and IRC). In addition, model simulat

results are sensitive to changes in parameters th

ence the amount of precipitation that eventually 

charges from ground water or interflow (INFILT

LZSN, UZSN). As indicated previously, ground

discharge to stream reaches is the dominant flow 

ponent in the Ipswich River Basin, followed by 

flow. Hence, uncertainties in the parameters tha

ground water will have the largest influence in m

performance, followed by uncertainties in inter

parameters. In general, model results are insens

wetland storage, possibly because the calibrated 

age is set sufficiently high that changes in stora

umes within the range tested do not produce mu

change in the flow characteristics examined. 

The absolute error in the flow characteris

(table 15) indicates that some perturbations imp

the model fit, compared to the base calibration. 

Changes in parameter values that decrease error 

some flow characteristics, however, also increas

error for other flow characteristics. In addition, 

decreases in runoff error at one station typically 

in increased runoff error at the other station. In g

the calibrated parameter values appear to yield t

overall model fit, that is, the least overall runoff 

RS

Vb Va –

Vb + Va

-------------------     Pb Pa –

Pb p + a

-----------------     = ⁄ × 100

AE

Vo Vs –

Vo

------------------     = × 100
Precipitation-Runoff Model 59

Table 14. Relative sensitivity of simulated flow characteristics to HSPF model parameter or storage change, Ipswich River Basin, Mass., 1989–93—Continued

Model 

parameter Change

Relative sensitivity (percent)

Total 

volume

10-

percent 

flow

50-

percent

flow

Evapotranspiration

Storm 

volume

Peak

flow

Base

flow Interflow Surface runoff

Volume

Summer Winter Summer 

storm

South Middleton station

INFILT 2x 1.9 -3.4 18 -2.6 -1.5 -27 1.6 -58 -9.3 10 0.10 -2.9

.5x -.11 5.8 -13 1.5 4.5 0 0 44 20 -8.2 1.8 5.6

LZSN 2x -6.2 -6.0 -6.3 40 -5.6 -27 0 -31 -1.9 -8.5 -5.6 -5.8

.5x 5.2 4.2 7.8 -4.8 4.9 0 0 26 1.2 11 3.6 5.6

UZSN 2x -9.7 -10 -12 -7.2 -33 -60 1.6 -19 70 -22 -7.8 -93

.5x 5.2 .25 13 -19 -17 -27 1.6 31 72 10 3.1 -61

INTFLW 2x .02 -.86 .63 -.08 -6.1 -27 0 8.2 -9.9 0 -.10 -2.9

.5x .03 2.2 -2.2 .15 13 0 0 -19 24 -.29 .46 8.3

IRC 2x -8.8 -91 119 0 11 0 17 .66 0 93 -32 -64

.5x .73 13 -15 0 23 23 0 2.0 0 -.43 2.8 33

LZETP 2x -16 -7.6 -29 16 -11 0 0 -15 18 -7.3 -23 19

.5x 23 17 33 -29 36 23 0 45 8.1 19 26 39

INTCEP 2x -2.5 -.40 -8.5 3.0 -2.5 -27 0 1.3 0 -9.3 -.92 -2.9

.5x 1.5 .35 5.1 -1.9 1.5 0 0 .65 -.09 5.6 .76 0

NSUR 2x -.03 -.25 .09 .02 -1.5 -27 0 2.9 -3.1 -.14 .05 0

.5x .06 .40 -1.0 -.02 1.5 .05 0 -.54 3.0 0 .10 0

LSUR 2x -.03 -.25 .09 .02 -1.5 -27 0 2.9 -3.1 -.14 .05 0

.5x .06 .40 -9.8 -.02 1.5 0 0 -.5 5.9 0 .10 0

KVARY 2x 1.8 6.1 -8.1 0 -3.0 -27 0 1.2 0 -9.0 6.2 -5.8

.5x -1.7 -5.4 7.2 0 2.5 0 0 1.2 0 7.8 -5.0 5.6

AGWRC 2x -425 -699 387 0 331 0 0 132 0 685 -927 617

.5x 6.5 29 -43 -.03 22 23 -4.8 1.2 0 -6.3 19 50

Wetland 2x -.08 .45 -1.6 0 6.4 0 0 1.2 0 2.1 -.72 16

FVOL .5x .03 .30 .36 0 -6.7 -27 1.6 1.2 0 -2.5 1.1 -21

mitted value range, 0.5x indicates the calibrated value was halved. 10percent flow indicates the flow that is equaled or exceeded 10 percent of the time (high flow). 50percent flow indicates the flow that 

is equaled or exceeded 50 percent of the time (low flow). Storm statistics determined from an average of 10 storms: 4/2/1990, 7/23/1990, 10/10/1990, 4/20/1991, 8/17/1991, 9/22/1991, 11/20/1991, 

3/10/1992, 9/25/1992, 12/10/1993. Model parameters: INFILT, Infiltration rate of soil; LZSN, Lower zone nominal storage; UZSN, Upper zone nominal storage. INTFLW, Interflow parameter; IRC, 

interflow recession constant; LZETP, Lower zone evapotranspiration; INTCEP, Interception storage; NSUR, Roughness of surface plain; LSUR, Length of surface plain; KVARY, ground water behavior 

constant; AGWRC, Active ground water recession constant; FVOL, reach storage.]
ecipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massachusetts

Ipswich station

INFILT 2x 1.6 -3.7 11 -2.3 -.60 -33 0 -59 -12 11 -.47 5.7

.5x .18 6.2 -12 1.0 3.5 0 0 44 26 -9.5 2.1 -5.9

LZSN 2x -15 -14 -11 3.7 0 0 0 -40 -6.3 -10 -17 16

.5x -3.6 -16 22 -8.6 13 0 0 -22 -18 23 -11 40

UZSN 2x -6.1 -5.9 -6.3 5.0 -5.5 0 0 -31 -2.9 -8.1 -5.6 -5.9

.5x 5.1 4.24 8.1 -4.7 5.9 0 0 25 1.6 10 3.4 5.7

INTFLW 2x -2.6 -.58 -8.6 2.9 -3.6 0 0 .41 .13 -10 -1.0 -12

.5x 1.7 .37 5.3 -2.0 2.4 0 0 0 0 6.3 .78 5.7

IRC 2x -10 -100 111 0 39 0 0 -4.6 0 123 -35 0

.5x .94 14 -14 0 21 27 0 1.6 0 -1.5 3.4 40

LZETP 2x -17 -8.5 -28 16 -24 -40 0 -20 15 -7.3 -23 0

.5x 23 17 34 -29 42 27 0 45 9.6 19 26 60

INTCEP 2x -2.6 -.58 -8.6 2.9 -3.6 0 0 .41 .13 -10 -1.0 -12

.5x 1.7 .37 5.3 -2.0 2.4 0 0 .35 0 6.3 .78 5.7

NSUR 2x -.02 -.32 .19 0 -1.8 0 0 2.3 -4.0 -.16 0 -5.9

.5x .06 .37 -.39 -.15 1.8 0 0 -.95 4.1 -.16 .05 0

LSUR 2x -.02 -.32 .19 0 -1.8 0 0 2.3 -4.0 -.16 0 -5.9

.5x .06 .37 -.39 -.15 1.8 0 0 -.95 4.3 -.16 .05 0

KVARY 2x 1.7 6.1 -9.0 0 -5.5 0 0 .70 0 -11 6.2 -25

.5x -1.6 -5.5 7.8 0 4.7 0 0 .70 0 8.5 -4.9 16

AGWRC 2x -423 -726 464 0 587 0 0 78 0 703 -898 1,818

.5x 6.1 28 -44 -.15 9.8 27 -3.2 .70 0 -17 21 26

Wetland 2x .29 .26 1.2 0 3.0 0 0 .70 0 2.2 -.16 11

FVOL .5x -.39 .05 -2.2 0 -3.0 0 0 .70 0 -2.8 .16 -18

Model 

parameter Change

Total 

volume

10-

percent 

flow

50-

percent

flow

Evapotranspiration

Storm 

volume

Peak

flow

Base

flow Interflow Surface runoff

Volume

Summer Winter Summer 

storm
Precipitation-Runoff Model 61

Table 15. Sensitivity of runoff characteristics as the percent error from the observed value to selected model PERLND parameters and wetland storage values, in 

the HSPF Ipswich River Basin model, Mass., 1989–93—Continued

Model 

parameter Change

Runoff error (percent difference from observed value)

Percent of total runoff

Total 

volume

10-

percent 

flow

50-

percent 

flow

Evapotranspiration

Storm

volume

Peak 

flow

Base 

flow

Volume

Summer Winter Summer 

storm Interflow Surface runoff

South Middleton station

Base calibration -1.7 -5.5 22 -19 -14 11 0 18 -2.9 83 25 16

INFILT 2x -.5 -7.6 37 -20 -15 -7.4 1.1 27 -2.9 79 17 15

0.5x -1.8 -1.8 11 -18 -11 11 0 12 -1.8 90 34 19

LZSN 2x -5.7 -9.2 17 5.9 -17 -7.4 0 12 -6.5 76 21 16

.5x 1.8 -2.8 28 -22 -11 11 0 27 -.56 90 30 16

UZSN 2x -7.8 -12 12 -23 -31 -26 1.1 1.9 -7.9 -3 22 26

.5x 1.8 -5.4 33 -28 -23 -7.4 1.1 27 -.93 21 31 27

INTFLW 2x -1.7 -6.1 22 -19 -17 -7.4 0 18 -3.0 79 27 15

.5x -1.7 -4.1 20 -19 -5.8 11 0 18 -2.6 93 22 19

IRC 2x -2.2 -11 31 -19 -13 11 1.1 25 -4.8 76 25 16

.5x -1.2 3.0 10 -19 .3 30 0 18 -1.1 128 26 16

LZETP 2x -10 -9.4 3.2 -11 -19 11 0 14 -14.8 103 23 18

.5x 14 5.7 52 -33 9.5 30 0 34 15.4 138 34 17

INTCEP 2x -3 -5.8 15 -17 -15 -7.4 0 11 -3.5 79 25 16

.5x -.7 -5.3 26 -20 -13 11 0 23 -2.4 83 25 16

NSUR 2x -1.7 -5.7 22 -19 -15 -7.4 0 18 -2.9 83 26 16

.5x -1.6 -5.3 21 -19 -13 11 0 18 -2.9 83 25 17

LSUR 2x -1.7 -5.7 22 -19 -15 -7.4 0 18 -2.9 83 26 16

.5x -1.6 -5.3 14 -19 -13 11 0 18 -2.9 83 25 17

KVARY 2x -.5 -1.6 15 -19 -16 -7.4 0 12 1.2 76 25 16

.5x -2.8 -8.8 28 -19 -12 11 0 25 -6.1 90 25 16

AGWRC 2x -4.2 -9.4 25 -19 -12 11 0 23 -8.2 90 25 16

.5x 2.7 15 -8.6 -19 0 30 -3.2 14 10.4 155 25 16

Wetland 2x -1.7 -5.2 20 -19 -10 11 0 20 -3.4 103 25 16

FVOL .5x -1.7 -5.3 22 -19 -18 -7.4 1.1 16 -2.2 59 25 16

HSPF, Hydrological Simulation ProgramFORTRAN. 2x indicates the calibrated value doubled except when limited by the permitted value range, 0.5x indicates the calibrated value was halved. 10percent 

flow indicates the flow that is equaled or exceeded 10 percent of the time (high flow). 50-percent flow indicates the flow that is equaled or exceeded 50 percent of the time (low flow). Storm statistics determined from an average of 10 storms: 4/2/1990, 7/23/1990, 10/10/1990, 4/20/1991, 8/17/1991, 9/22/1991, 11/20/1991, 3/10/1992, 9/25/1992, 12/10/1993. Model parameters: INFILT, Infiltration rate of 

soil; LZSN, Lower zone nominal storage; UZSN, Upper zone nominal storage; INTFLW, Interflow parameter; IRC, interflow recession constant; LZETP, Lower zone evapotranspiration; INTCEP, Interception storage; NSUR, Roughness of surface plain; LSUR, Length of surface plain; KVARY, ground water behavior constant; AGWRC, Active ground water recession constant; FVOL, reach storage.]
ecipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massachusetts

Ipswich station

Base calibration -3.3 -4.9 5.6 -24 34 69 0 -2.1 2.0 70 26 11

INFILT 2x -2.3 -7.1 14 -25 33 35 0 5.2 1.7 76 17 11

.5x -3.2 -.83 -2.6 -24 37 69 0 -8.1 3.4 63 34 14

LZSN 2x -13 -13 -2.0 -22 34 69 0 -8.6 -9.0 90 20 11

.5x -5.6 -14 22 -29 45 69 0 14 -5.5 122 22 10

UZSN 2x -7.2 -8.5 1.3 -22 29 69 0 -7.3 -1.7 63 21 11

.5x .08 -2.1 11.4 -27 39 69 0 4.9 4.3 76 30 12

INTFLW 2x -3.3 -5.5 6.2 -24 27 35 0 -2.1 1.9 63 27 11

.5x -3.3 -3.3 4.1 -24 44 69 0 -2.3 2.3 83 23 14

IRC 2x -3.9 -10 13 -24 37 69 0 5.4 -.11 70 25 11

.5x -2.7 4.5 -3.7 -24 54 102 0 -3.1 4.3 122 26 11

LZETP 2x -11.8 -9.3 -9.6 -17 17 35 0 -6.0 -10 70 23 12

.5x 12.7 6.3 32.2 -38 77 102 0 11 21 155 35 12

INTCEP 2x -5.0 -5.2 -.27 -23 30 69 0 -8.4 1.3 57 26 11

.5x -2.2 -4.6 9.4 -25 36 69 0 2.1 2.5 76 26 11

NSUR 2x -3.3 -5.1 5.8 -24 32 69 0 -2.2 2.0 63 26 11

.5x -3.2 -4.6 5.4 -24 35 69 0 -2.2 2.0 70 25 12

LSUR 2x -3.3 -5.1 5.8 -24 32 69 0 -2.2 2.0 63 26 11

.5x -3.2 -4.6 5.4 -24 35 69 0 -2.2 2.0 70 25 12

KVARY 2x -2.2 -.90 -.54 -24 29 69 0 -9.2 6.3 44 26 11

.5x -4.3 -8.3 11 -24 38 69 0 3.6 -1.3 90 26 11

AGWRC 2x -5.7 -8.9 8.6 -24 38 -83 0 2.1 -3.4 90 26 11

.5x .72 15 -21 -24 43 102 -2.1 -13 17 103 26 11

Wetland 2x -3.1 -4.7 6.5 -24 36 69 0 -.6 1.9 83 26 11

FVOL .5x -3.5 -4.8 4.1 -24 31 69 0 -3.9 2.1 50 11 11

Model 

parameter Change

Runoff error (percent difference from observed value)

Percent of total runoff

Total 

volume

10-

percent 

flow

50-

percent 

flow

Evapotranspiration

Storm

volume

Peak 

flow

Base 

flow

Volume

Summer Winter Summer 

storm Interflow Surface runoff
Application of the Model: Effects of Water Withdrawals on Stream

Model Limitations

Mathematical models that are used to represent 

complex natural systems are simplified by necessity, 

both in terms of the processes simulated and the physical representation of the system. Hence, there are 

inherent limitations to the types of questions that can 

be appropriately addressed by the model. The Ipswich 

River Basin precipitation-runoff model was conceptualized and calibrated to evaluate the effects of water 

withdrawals from relatively shallow ground water and 

surface sources on streamflow. The model can be used 

to evaluate many water-resource management questions by providing information about the effects of 

alternative management scenarios, or by generating 

data that would be difficult to obtain otherwise. The 

model may not be an appropriate tool to evaluate some 

management questions, however, and the simulation 

results could be incorrect or misleading, which could 

lead to poor management decisions. Therefore, the use 

of the model and results of simulations should always 

be weighed in the context of the inherent limitations of 

the model.

For example, the use of this model may not be 

appropriate to evaluate the effects on streamflow of 

wells tapping fractured bedrock, because ground water 

in fractured bedrock can have a widely variable area of 

recharge and natural discharge. One of the underlying 

assumptions in the streamflow depletion program 

(STRMDEPL) developed for this study is that the 

pumped well is completed in a uniform aquifer with a 

fully-penetrating stream. The accuracy of streamflow 

depletion calculated by STRMDEPL depends closely 

on how well the actual aquifer conditions fit the underlying assumptions. Without detailed geohydrologic 

investigations of bedrock aquifer conditions, application of the STRMDEPL program to determine any 

streamflow depletions caused by bedrock wells would 

have a high degree of uncertainty.

Another consideration in evaluating model simulation results is the degree to which the model was calibrated. A good fit was obtained between simulated and 

observed flows over a wide range of conditions for the 

Ipswich River at the South Middleton and Ipswich stations; however, most reaches were ungaged and the 

model could not be calibrated for stream reaches below 

the Ipswich station. Furthermore, the calibration 

reflects the combined effects of various hydrologic 

response units (PERLNDs and IMPLNDs) and reach 

characteristics. Hydrologic judgment was used to 

represent the response of different PERLNDs a

IMPLNDs, but no information was available to 

itly calibrate the unique HRUs. Therefore, simu

results from ungaged areas or changes in flow p

duced by the variation of the properties of HRU

uncertain, and the results should be viewed as ev

of a relative change instead of an absolute chan

Stage, storage, and discharge characteristics of 

(including wetlands) are determined from meas

channel geometry to the extent possible, but ma

tors, such as channel roughness and the large nu

of changes in channel geometry along a stream 

could not be measured within the scope of this 

The stage, storage, and, discharge characteristic

stream reach affect the flow routing in the mode

the stream stage at a given discharge.

APPLICATION OF THE MODEL: 

EFFECTS OF WATER WITHDRAWALS 

ON STREAMFLOW

The Ipswich River Basin model was deve

as a tool to evaluate the response of streamflow 

various water withdrawal scenarios. Results of 

simulation of these scenarios, along with those 

any future scenarios that might be tested, will h

water-resource planners develop management s

gies to satisfy water supply needs while simultan

maintaining flows to protect the river ecosystem

hypothetical scenarios identified by the Ipswich 

Task Force Science and Data Committee as imp

to understanding the effects of water withdrawa

were simulated: 

1. Stopping all withdrawals during the 1989–

calibration period, 

2. Only ground-water withdrawals for the 

calibration period, 

3. Only surface-water withdrawals for the 

calibration period,

4. Simulate long-term (1961–95) streamflow

1991 land-use conditions as developed i

calibrated model, and stopping all withd

5. Simulate long-term streamflow conditions 

reverting developed HRUs to undevelop

HRUs and stopping all withdrawals, and

6. Simulate long-term streamflows in respon

average 1989–93 water withdrawals.
64 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

A new model run file (uci) and unique scenario 

identification was created for each scenario. Simulation 

results for each scenario were targeted to a unique data 

set in the WDM file so that the scenarios could be compared. Table 16 summarizes the scenarios, model run 

files, and output data sets. 

All scenarios required modification of the base 

model run file (ips.uci) to change withdrawal rates in 

the external source block (EXT SOURCES) and to 

output streamflow to unique DSNs in the external 

target (EXT TARGET) block. The GLOBAL block was 

also modified in the last three scenarios to change the 

simulation period. Scenario 5 converted all developed 

HRUs (PERLNDs 3 through 7 and 10 through 13, and 

IMPLND 1 and 2) to forested HRUs (PERLNDs 1 and 

8) with similar surficial geology by changing the drainage areas from developed HRUs to undeveloped HRUs 

in the SCHEMATIC block. This scenario approximates 

the natural flow of the river by stopping withdrawals 

and reverting land use to undeveloped conditions. 

Scenario 6 required streamflow depletion from groundwater and surface-water withdrawals over the 1961–95 

period; however, these data were generally unavailable 

except for the calibration period (table 4). Water withdrawals were estimated for periods of missing data for 

each reach by averaging daily withdrawals for each 

month that data were available and generating a 

daily withdrawal for each month for periods of 

record.

Simulation results for the scenarios provi

tive differences between streamflows under diff

water withdrawals and land uses. Results are be

pared in groups of scenarios with similar time s

that the differences between model runs represe

ferences between scenarios and not the differen

between climatic conditions. The first three sce

span the 1989–93 period used to calibrate the m

water withdrawals during this period are mostly 

reported records. The last three scenarios span t

1961–95 period; water withdrawals (when inclu

the simulation) are mostly estimated from the r

withdrawals for the 1989–93 period and do not 

changing water use over this period. The report

ground-water withdrawals were relatively const

from year to year for similar months. The repor

surface withdrawals are often dependent on strea

and thus, are subject to wider variations in mon

values.

Calibration-Period Simulations

Flow-duration curves for simulations of t

1989–93 period are shown in figure 24 for the b

simulation and for scenarios with (1) no withdr

(2) only surface-water withdrawals, and (3) onl

ground-water withdrawals. Flow-duration curve

nearly identical for the base simulation and simu

with only ground-water withdrawals at both the 

Middleton and Ipswich stations. Flow-duration 

are also nearly identical for simulations with no 

drawals and simulations with only surface-wate

withdrawals at both the South Middleton and Ip

stations. The two sets of curves differ by about a

of magnitude at the 99.8 percent exceedence pr

ity at both sites. This indicates that surface-wate

withdrawals have little effect on the duration an

quency of low flows and that the ground-water 

withdrawals have a large effect on the magnitud

duration, and frequency of low flows. The relati

difference between curves is somewhat larger a

South Middleton station than at the Ipswich sta

because of the relatively greater rate of ground-

withdrawal with respect to streamflow above th

South Middleton station than above the Ipswich 

Table 16. Alternative water withdrawal and land-use scenarios 

simulated for the Ipswich River Basin, Mass.

Scenario Model run file

Scenario 

identification

Output data 

set numbers

1. Stop all withdrawals No_demd.uci No_demd 6001 to 6066

2. Ground-water 

withdrawals only

No_GWdem.uci No_GWdem 6101 to 6166

3. Surface-water 

withdrawals only

No_SWdem.uci No_SWdem 6201 to 6266

4. Long-term with 

no water-supply 

demands

LT-NoDem.uci LT-NoDem 6301 to 6366

5. Long-term undeveloped land use 

and no water 

demands

LT-Undev.uci LT-Undev 6401 to 6466

6. Long-term with 

1989–93 average 

water withdrawals

LT-Demd.uci LT-Demd 6501 to 6566
Application of the Model: Effects of Water Withdrawals on Stream

station. The differences between curves diminis

the exceedence probability decreases; little diff

between curves is indicated below the 50 perce

exceedence probability at both sites. This indica

that water withdrawals have little effect on high 

and medium flows at either station.

Hydrographs of simulated daily flows fur

illustrate the effect of ground-water withdrawal

on low flows (fig. 25). During most of the year 

hydrographs for the various scenarios are nearly 

identical; during periods of low flow (especially 

during the summers of 1991 and 1993), howeve

the hydrograph with no withdrawals and the 

hydrograph with only surface-water withdrawal

sustained at a higher discharge than the hydrogr

for the base simulation or that with only ground

withdrawals. 

Long-Term Simulations

Long-term simulations (1961–95) indicat

that the differences in streamflow between scen

with no withdrawals and those with average wa

withdrawals (fig. 26) are similar to the differenc

in streamflow for the 1989–93 simulations for s

types of scenarios. The flow-duration curve for 

veloped land use with no withdrawals is similar 

the flow-duration curve with no withdrawals wi

1991 land-use conditions (fig. 24). Small differ

can be noted in the flow-duration curves betwee

simulations with undeveloped land use with no 

drawals and simulations with no withdrawals w

1991 land-use conditions for medium- to low-fl

conditions at the South Middleton station and 

medium- to high-flow conditions at the Ipswich 

station. The differences in duration curves for 

low-flow conditions at the South Middleton stat

reflect the greater infiltration and increased base 

flow under undeveloped conditions than develo

conditions, whereas the lack of difference at the 

Ipswich station (which has less developed land 

than above the South Middleton station) reflect 

greater lower zone evapotranspiration between 

forested and open land which offsets any gains 

base flow.

DISCHARGE, IN CUBIC FEET PER SECOND

PERCENT CHANCE DISCHARGE EXCEEDED

A. SOUTH MIDDLETON STATION

B. IPSWICH STATION

0.1

1

10

100

1,000

1

10

100

1,000

10,000

0.5 10 90 1 5 20 50 80 95 99 2 30 70 98 99.8

BASE SIMULATION

NO WITHDRAWALS

SURFACE-WATER

 WITHDRAWALS ONLY

GROUND-WATER

 WITHDRAWALS ONLY

EXPLANATION

Figure 24. Flow-duration curves developed from simulated 

daily flows for current conditions (base simulation) and three 

scenarios—no withdrawals, only surface-water withdrawals, 

and only ground-water withdrawals—for the Ipswich River at 

the (A) South Middleton and (B) Ipswich stations, Mass., 

1989–93.
66 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

0.1

1

10

100

1,000

1

10

100

1,000

10,000

1989 1990 1991 1992 1993

EXPLANATION

DISCHARGE, IN CUBIC FEET PER SECOND

A. SOUTH MIDDLETON STATION

B. IPSWICH STATION

BASE SIMULATION

NO WITHDRAWALS

SURFACE-WATER

 WITHDRAWALS ONLY

GROUND-WATER

 WITHDRAWALS ONLY

Figure 25. Discharge for current conditions (base simulation) and three scenarios—no withdrawals, only surface-wate

withdrawals, and only ground-water withdrawals—for the Ipswich River at the (A) South Middleton and (B) Ipswich stat

Mass., 1989–93.
Application of the Model: Effects of Water Withdrawals on Stream

Long-term simulations enabled the comp

of low-flow-frequency probabilities by fitting an

series of low flows to the log-Pearson Type III d

tion. Low-flow frequency probabilities were co

from annual series of minimum 1-day, 7-day, an

day mean flows for each of the long-term simul

scenarios using SWSTAT, a program designed t

pute surface-water statistics (Lumb and others, 

The low-flow frequency curves computed from 

simulated daily discharges for each of the long-

scenarios are shown for each period of minimum 

in figure 27. 

The 1-day low-flow probability curve ind

the minimum daily discharge that is likely to oc

the specified recurrence interval (bottom x-axis)

is the reciprocal of the probability of non-excee

(top x-axis). For instance, streamflow at the Sou

Middleton station for simulations with no water 

drawals and 1991 land use indicate that the min

daily flow with a recurrence probability of 50 y

2.9 ft3/s. Flows might not fall below 2.9 ft3/s in 

50-year period or could fall below this level mo

once in a 50-year period; over a long period of 

however, this minimum daily flow would be exp

to occur, on average, once in 50 years if no wat

withdrawals were being made. 

Minimum daily flows for simulations wit

withdrawals with 1991 land-use conditions and 

withdrawals with undeveloped land-use conditi

were comparable. At the South Middleton statio

flows ranged from 2.7 and 3.5 ft3/s at the 100-y

recurrence interval to 9.9 and 15 ft3/s at about t

1-year recurrence interval for simulations with 

(1) no withdrawals with 1991 land-use conditio

and (2) no withdrawals with undeveloped land-

conditions, respectively. At the Ipswich station, 

flows ranged from 5.8 and 5.5 ft3/s at the 100-y

recurrence interval to 23 and 21 ft3/s at about th

1-year recurrence interval for simulations with 

(1) no withdrawals with 1991 land-use conditio

and (2) no withdrawals with undeveloped land-

conditions, respectively. Simulations with no w

drawals with 1991 land-use conditions and thos

with undeveloped land-use conditions indicate 

undeveloped land-use conditions resulted in 

increased discharge above South Middleton stat

slightly decreased discharge at the Ipswich stati

B. IPSWICH STATION

A. SOUTH MIDDLETON STATION

NO WATER WITHDRAWALS

 AND 1991 LAND USE

NO WATER WITHDRAWALS

 AND UNDEVELOPED LAND USE

AVERAGE 1989–93 WATER WITHDRAWALS 

 AND 1991 LAND USE 

EXPLANATION

PERCENT CHANCE DISCHARGE EXCEEDED

DISCHARGE, IN CUBIC FEET PER SECOND

1

10

100

1,000

10,000

0.5 2 5 10 20 50 70 90 95 98 99.5

0.1

1

10

100

1,000

0.5 2 5 10 20 50 70 90 95 98 99.5

Figure 26. Flow-duration curves for average water 

withdrawals with 1991 land-use conditions, no withdrawals 

with 1991 land-use conditions, and no withdrawals with 

undeveloped land-use conditions, for the Ipswich River at 

the (A) South Middleton, and (B) Ipswich stations, Mass., 

for long-term simulations (1961–95).
68 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

NO WITHDRAWALS AND

 1991 LAND USE

NO WITHDRAWALS AND

 UNDEVELOPED LAND USE

AVERAGE 1989–1993 

 WATER WITHDRAWALS

 AND 1991 LAND USE

A. 1-DAY LOW-FLOW FREQUENCY

B. 7-DAY LOW-FLOW

C. 30-DAY LOW-FLOW

0

5

10

15

20

25

1.01 1.02 1.04 1.11 1.25 2 5 10 20 50 100

0

5

10

15

20

0

5

10

15

20

0.99 0.98 0.96 0.9 0.8 0.5 0.2 0.1 0.05 0.02 0.01

1.01 1.02 1.04 1.11 1.25 2 5 10 20 50 100

0

10

20

30

40

50

60

0

5

10

15

20

25

30

IPSWICH STATION

0.99 0.98 0.96 0.9 0.8 0.5 0.2 0.1 0.05 0.02 0.01

0

5

10

15

20

25

30

RECURRENCE INTERVAL, IN YEARS

DISCHARGE, IN CUBIC FEET PER SECOND

NON-EXCEEDENCE PROBABILITY

SOUTH MIDDLETON STATION

EXPLANATION

Figure 27. Log-Pearson Type III low-flow exceedence probabilities and recurrence intervals for (A) 1-day, 

(B) 7-day, and (C) 30-day annual minimum mean streamflows based on long-term (1961–95) simulations of 

average water withdrawals, no withdrawals with 1991 land-use conditions, and no withdrawals with 

undeveloped land-use conditions, for the Ipswich River at the South Middleton and Ipswich gaging stations, 

Mass.
Application of the Model: Effects of Water Withdrawals on Stream

This indicates that the imperviousness above the South 

Middleton station under the 1991 land-use condition 

was sufficient to inhibit infiltration and, thereby, 

decrease baseflow. This is underscored by the fact 

that under relatively less developed conditions at the 

Ipswich station, the undeveloped condition resulted 

in lower flow through evapotranspiration than the 

developed condition. 

Minimum daily flows for simulations with average 1989–93 withdrawals were considerably less than 

the minimum daily flows for simulations with no withdrawals for either land-use condition. At the South 

Middleton station, flows with water withdrawals 

ranged from 0.32 ft3/s at the 100-year recurrence interval to 2.0 ft3/s at about the 1-year recurrence interval. 

At the Ipswich station, flows with water withdrawals 

ranged from 0.84 ft3/s at the 100-year recurrence interval to 13 ft3/s at about the 1-year recurrence interval.

The 7-day low-flow frequency represents the 

minimum flows over a continuous 7-day period. The 

7-day low-flow probabilities are similar to, but slightly 

greater than, the 1-day low-flow probabilities. At the 

South Middleton station, flows ranged from 2.9 and 

3.8 ft3/s at the 100-year recurrence interval to 11 and 

16 ft3/s at about the 1-year recurrence interval for simulations with (1) no withdrawals with 1991 land use 

conditions, and (2) no withdrawals with undeveloped 

land conditions, respectively. At the Ipswich station, 

flows ranged from 6.0 and 5.7 ft3/s at the 100-year 

recurrence interval to 25 and 22 ft3/s at about the 

1-year recurrence interval for simulations with (1) no 

withdrawals with 1991 land-use conditions and (2) no 

withdrawals with undeveloped land conditions, respectively. Minimum 7-day flows for simulations with 

water withdrawals ranged from 0.38 ft3/s at the 

100-year recurrence interval to 3.0 ft3/s at about the 

1-year recurrence interval at the South Middleton station, and from 1.5 ft3/s at the 100-year recurrence interval to 15 ft3/sec at about the 1-year recurrence interval 

at the Ipswich station.

The 7-day, 10-year, low-flow (7Q10), which represents the probable minimum flow over a 7-day period 

that will occur on average once in 10 years, is a widely 

used regulatory statistic. At the South Middleton station, the 7Q10 flows were 4.1 ft3/s, 5.9 ft3/s, and 

0.54 ft3/s for simulations with (1) no withdrawals 

with 1991 land-use conditions, (2) no withdrawals 

with undeveloped land-use conditions, and (3) average 

water withdrawals with 1991 land-use conditions, 

respectively. At the Ipswich station, the 7Q10 fl

were 8.3 ft3/s, 8.2 ft3/s, and 2.7 ft3/s for simulat

with (1) no withdrawals with 1991 land use con

(2) no withdrawals with undeveloped land cond

and (3) average water withdrawals with 1991 la

conditions, respectively. 

The 30-day low-flow frequency represent

minimum annual flow over a continuous 30-day 

The 30-day low-flow probabilities are similar, b

larger, than flows at the 1- and 7-day low-flow p

bilities. At the South Middleton station, flows r

from 3.4 ft3/s and 4.7 ft3/s at the 100-year recur

interval to 17 ft3/s and 21 ft3/s at about the 1-ye

recurrence interval for simulations with (1) no w

drawals with 1991 land-use conditions and (2) n

withdrawals with undeveloped land conditions, 

tively. At the Ipswich station, flows ranged from 

7.6 ft3/s and 6.6 ft3/s at the 100-year recurrence 

val to 50 ft3/s and 37 ft3/s at about the 1-year 

recurrence interval for simulations with (1) no w

drawals with 1991 land use conditions and (2) n

withdrawals with undeveloped land conditions, 

tively. Minimum 30-day flows for simulations w

water withdrawals ranged from 0.52 ft3/s at the 

100-year recurrence interval to 17 ft3/s at the 1-

recurrence at the South Middleton station, and f

3.1 ft3/s at the 100-year recurrence interval to 4

at the 1-year recurrence interval at the Ipswich 

Low flows for simulations with no water 

drawals and undeveloped land use tend to decre

ative to simulations with no water withdrawals 

1991 land-use conditions for return intervals of 

years or less for all duration periods, and especi

the 30-day low-flow period. At the Ipswich stat

30-day low flow for no withdrawals with undev

conditions was less than the 30-day low flow wi

age water withdrawals as the return period appr

1 year. This suggests that the evaporation losses

are greater in forested PERLNDs than in other 

PERLND types, become increasingly importan

establishing the long-duration (e.g., 30-day inte

low-flow characteristic for short return intervals

Because the amount of effective impervio

area in the basin is uncertain, another simulatio

was made (LT-imp.uci) for the 1961–95 period 

average 1989–93 withdrawals, but with the effe

impervious area set equal to the initial estimated 

of effective imperviousness shown in table 6. T

simulation required shifting area from disturbed 

PERLNDs into the corresponding IMPLNDs an
70 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

represents about a 50 percent increase in the effective 

impervious area in the Ipswich River Basin model. 

Results of this simulation can be used to assess the 

hydrologic effects of changes in effective impervious 

area and can provide a reasonable upper limit to the relative hydrologic change from a undeveloped to an 

developed land-use condition. 

Flow duration curves for simulated daily flows 

made with increased effective impervious area are 

nearly identical to the flow duration curves for simulated daily flows with the calibrated effective impervious area at both the South Middleton and Ipswich 

stations. Small changes in the computed log-Pearson 

low-flow-frequency probabilities were noted, however, 

between simulated flows made with the different effective impervious areas. Simulation results with the 

larger effective impervious area indicated that the minimum annual daily flow decreased by about 7 percent 

over the entire range of recurrence intervals compared 

to the minimum annual daily flow for simulations made 

with the calibrated effective impervious area at the 

South Middleton station. At the Ipswich station, the 

minimum annual daily flow decreased by about 6 percent for return periods that approached 1-year, but 

increased by about 5 percent for return periods of 5 

or more years. Thus, the difference in the 1-day low 

flow between simulations made with undeveloped 

land-use conditions and developed land-use conditions 

would generally be larger, particularly at the South 

Middleton station (more developed) when the effective 

imperviousness is increased to a reasonable upper 

limit.

Simulations made with increased impervious 

area indicated that the 30-day low flow increased by 

1.3 percent for a 100-year recurrence interval to 13 

percent for about a 1-year recurrence interval at the 

South Middleton station compared to flows simulated 

with the calibrated impervious area; a similar, but 

smaller increase was noted at the Ipswich station. This 

increase in the 30-day low flow reflects the increased 

runoff from storms that likely occur during a 30-day 

period, but as previously noted, the flow between 

storms will generally be less as a result of increased 

imperviousness. In general, the differences between 

flow characteristics for simulations made with t

brated effective impervious area and the initial 

tive impervious area are small at the stream-gag

stations, but changes in the effective imperviou

will have a greater impact in subbasins that are 

developed than in subbasins with less developm

which is evident from the relatively large chang

flow characteristics at the South Middleton stat

compared to those at the Ipswich station. 

SUMMARY

The Ipswich River Basin supplies water t

about 330,000 residents in 23 municipalities in 

near the basin. Urbanization and decreases in st

flow resulting from water withdrawals in the ba

are of concern because of the potential effects o

aquatic habitat, water quality, and recreational u

of the river. Impaired flow, low dissolved oxyge

centrations, high nutrient concentrations, and th

ence of pathogens in the river have led regulator

the river under Section 303(d) of the Federal Cl

Water Act as non-compliant with the Massachu

Water Quality Standards. This listing requires t

Massachusetts develop a management plan to a

the impairments. 

During the 1989–93 study period, averag

monthly water withdrawals from all sources exc

monthly mean streamflow above the South Mid

gaging station during July and approaches mon

mean streamflow during September. Average 

monthly pumping above the Ipswich gaging sta

approaches the mean monthly streamflow durin

during the 1989–93 period. During 1989–93, gr

water withdrawals always exceeded surface-wa

withdrawals above the South Middleton station

ground-water withdrawals exceeded surface-wa

withdrawals only during June through October 

the Ipswich station because the state water-use 

restrict surface-water withdrawals between May 

October. 

The Hydrological Simulation ProgramFORTRAN (HSPF) was used to simulate the hy

ogy and complex water withdrawals in the basi
Sum

Model development involved (1) collecting and assembling data on climate, streamflow, and water-use or 

estimating this data when necessary, (2) subdividing 

the land surface into units of similar hydrologic 

response (HRUs) and the streams into reaches, 

(3) determining the hydraulic characteristics of each 

reach, and (4) determining the effects of water 

withdrawals on streamflows. 

Time series of climate, streamflow, and water 

withdrawals were compiled and entered into the 

Watershed Data Management system data base. Spatial 

grids of climate data for the basin were developed by 

the Marine Biological Laboratory (MBL) from 

National Weather Service data. Grid cells were averaged to obtain a single set of climatic time series (centroid) for use in the model. The climate data generally 

are hourly and date back to 1961. Daily streamflow 

observations on the Ipswich River at South Middleton 

and at Ipswich gaging stations began in the 1930’s. 

Daily water withdrawal data (often estimated from 

monthly values) generally began in 1989. 

Land-surface and hydraulic data were compiled 

to discretize the basin and set model parameters. The 

model includes 15 pervious HRUs (PERLNDs), and 2 

impervious HRUs (IMPLNDs), that were developed 

from unique combinations of land use, surficial geology, and water-use practices to represent the basin. The 

Ipswich River and its main tributaries were segmented 

into 67 stream reaches (RCHRES) based on hydrology, 

water withdrawals, and in a few cases, on habitat considerations. Wetlands cover about 21 percent of the 

Ipswich River Basin, and because of their effects on the 

hydrology of the basin, additional RCHRES were 

defined for most channel segments to represent wetland 

storage.

Streamflow depletions resulting from groundwater withdrawals were calculated using STRMDEPL, 

a computer program that analytically computes the 

delayed effects of ground-water withdrawals on 

streamflow based on daily pumping rate of wells, aquifer and streambed properties, and the distance of the 

pumped well from the stream.

The model was calibrated to measured st

flow at the South Middleton and Ipswich station

the period 1989–93 because water-use informat

could be obtained or estimated, and because 19

land-use data were used to define the HRUs. M

parameter values were calculated from available 

data to the extent possible, and then an iterative 

was used to adjust values to minimize the differ

between simulated and observed flows. Parame

values were calibrated using precipitation data 

Reading, Mass. and from the MBL centroid dat

because of uncertainty in which data best repre

precipitation over the basin. The model was cal

to annual, monthly, and daily flows to provide t

model fit, particularly during low-flow periods. 

Mean annual discharge at the South Midd

station is undersimulated on average by 2.1 perc

simulations made with centroid precipitation da

oversimulated by 2.2 percent for simulations m

with Reading precipitation data. Mean annual d

charge at Ipswich is undersimulated on average 

percent for simulations made with centroid prec

tion data and oversimulated on average by abou

percent for simulations made with Reading prec

tion data. The coefficient of model-fit efficiency 

cates that at a minimum, the model explained 9

percent of the variance in the observed monthly 

and 79 percent of the variance in the observed d

flow for simulations made with either precipitat

source. Hydrographs of simulated daily mean d

charge for 1989–93 at the South Middleton and 

Ipswich stations parallel the observed hydrogra

over a wide range of flow conditions and season

Flow-duration curves computed from simulated 

observed daily discharge at the South Middleto

Ipswich stations for 1989–93 indicate a similar 

tude and frequency of flow. In general, the mod

was slightly better for simulations made with th

centroid precipitation data than for simulations 

with the Reading data; therefore, the centroid pr

tion was used to evaluate various water-withdra

scenarios.
72 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

The GenScn decision-support-system software 

was used to facilitate examination of six water-use 

scenarios for this report. Three scenarios each were 

examined for the 1989–93 period and three for the 

1961–95 period. The calibration-period scenarios were 

compared to the base scenario of calibrated flows 

resulting from existing water-use practices to evaluate 

the effects of water withdrawals on streamflow. The 

calibration-period scenarios included (1) stopping all 

withdrawals, (2) only ground-water withdrawals, and 

(3) only surface-water withdrawals. The long-term 

simulations (1961–95) were used to test the effects of 

withdrawals on streamflow over a wider range of climatic conditions and to compute 1-, 7-, and 30-day 

low-flow frequencies using log-Pearson Type III analysis. The long-term simulations included: (1) stopping 

all withdrawals under 1991 land-use conditions as 

developed in the calibrated model, (2) stopping all 

withdrawals and reverting developed HRUs to undeveloped HRUs to predict what the natural streamflow 

would have been, and (3) simulations of average 1989–

93 water withdrawals and 1991 land use. 

Flow-duration curves and hydrographs developed from the various withdrawal scenarios for the calibration period indicate that surface-water withdrawals 

have little or no effect on low flows but the groundwater withdrawals have a large effect on low flows. At 

both gaging stations, flow-duration curves are about 

an order of magnitude lower at the 99.8 percent 

exceedence probability for the 1989–93 water withdrawals and the simulation with only ground-water 

withdrawals as compared to the simulations with no 

water withdrawals and with only surface-water withdrawals. The relative difference between curves is 

somewhat larger at the South Middleton station than 

at the Ipswich station because the ground-water 

withdrawals are a larger proportion of the streamflow 

at South Middleton than at Ipswich. Differences 

between curves diminish as the probability of 

exceedence decreases to 50 percent. During periods 

of low flow (especially during the 1991 and 1993 summers), hydrographs for the simulations with no 

withdrawals and only surface-water withdrawal

sustained at higher discharges than the hydrogr

for the base simulation and the simulation with 

ground-water withdrawals. The surface-water 

withdrawals have little effect on the flow durati

because they are restricted to times of relatively 

flow when the withdrawals are only a small por

of the total flow.

Results of long-term simulations were sim

those for the same scenarios for 1989–93 simula

both sites. Low flows for simulations with avera

calibration-period water withdrawals were subs

tially lower than simulations with (1) no water w

drawals with 1991 land use, and (2) simulations 

no water withdrawals with undeveloped land us

example, at the South Middleton station the 7-d

year low-flow (7Q10), a widely used regulatory 

tic, was 0.54, 4.1, and 5.9 ft3/s, for simulations 

(1) average 1989–93 water withdrawals and 199

use, (2) no withdrawals and 1991 land use, and 

withdrawals and undeveloped land use, respecti

the Ipswich station, the 7Q10 was 2.7 ft3/s for s

tions with average 1989–93 water withdrawals, 

about 8.3 ft3/s for simulations with no withdraw

with either 1991 land use or undeveloped land u

The Ipswich River Basin precipitation-ru

model was conceptualized and calibrated to eva

the effects on streamflow of water withdrawals 

shallow ground-water wells and from surface so

As such, the model can be used to evaluate a num

management scenarios or to predict flow under 

tions that would be difficult or impossible to ob

otherwise. Although the model is well calibrate

observed data, consideration should be given to 

inherent uncertainty of the model simulations.
Refere

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APPENDIX A

Documentation of Computer Program

STRMDEPL—A Program to Calculate Streamflow 

Depletion by Wells Using Analytical Solutions

By Paul M. Barlow

Appen

CONTENTS

Summary ...........................................................................................................................................................................

Analytical Solutions for Streamflow Depletion by Wells .................................................................................................

Description of Computer Program STRMDEPL ..............................................................................................................

Sample Problem for Ipswich River Basin .........................................................................................................................

References .........................................................................................................................................................................

FIGURES

1. Example input file for program STRMDEPL....................................................................................................

2. Example result file generated by program STRMDEPL ...................................................................................

3. Example plot file generated by program STRMDEPL......................................................................................

4. Graph showing specified daily pumping rates at well Wenham Well 1, 1989–97, and calculated 

streamflow depletion..........................................................................................................................................

Appen

SUMMARY

The computer program STRMDEPL calculates time-varying streamflow depletion caused by 

pumping at a well. The program is based on two 

analytical solutions to the ground-water flow equation for the condition of a pumping well in a semiinfinite, homogeneous, and isotropic aquifer in 

direct hydraulic connection with a straight and 

fully penetrating stream. One solution assumes 

unimpeded connection between the stream and 

aquifer (Jenkins, 1968); the other solution 

accounts for resistance to flow at the boundary 

between the stream and aquifer caused by semipervious streambed and streambank materials 

(Hantush, 1965). Superposition is used to calculate 

the influence of time-varying daily pumping rates 

on streamflow depletion. This document summarizes the analytical solutions on which the program 

is based, describes the program and its input 

requirements, and presents a sample problem 

based on a pumped well near the Ipswich River, 

Massachusetts.

ANALYTICAL SOLUTIONS FOR 

STREAMFLOW DEPLETION BY WELLS

Several analytical solutions are available for the 

determination of streamflow depletion by wells. These 

include steady-state solutions by Newsom and Wilson 

(1988) and Wilson (1993) and transient solutions by 

Theis (1941), Conover (1954), Glover and Balmer 

(1954), Glover (1960), Theis and Conover (1963), 

Hantush (1964, 1965, and 1967), Jenkins (1968), and 

Weeks and Appel (1984). The most often applied analytical solution for determining time-varying rates of 

streamflow depletion by wells is that presented in 

Jenkins (1968). For application of this solution, several 

simplifying assumptions concerning the aquifer and 

adjoining stream must be made. These assumptions, 

which are described in Theis (1941), Glover and 

Balmer (1954), and Jenkins (1968), are listed here for 

reference:

1. The aquifer is isotropic, homogeneous, an

semi-infinite in areal extent;

2. The transmissivity of the aquifer does not 

with time. Thus, for a water-table aquife

drawdown is considered to be negligible 

compared to the initial saturated thickne

the aquifer;

3. The stream that forms a boundary to the aq

straight, fully penetrates the aquifer, and 

direct hydraulic connection with the aqu

4. The stage of the stream (as well as the gro

water head at the stream boundary) rem

constant with time;

5. Water is released instantaneously from sto

6. The well is open to the full saturated thick

the aquifer; and

7. The pumping rate is steady during any per

pumping.

The analytical solution presented in Jenk

(1968) is

 , 

where

and

is the rate of streamflow depletion (cubic 

per time);

is the pumping rate of the well (cubic len

time);

is the perpendicular distance from the w

the stream (length);

is the storativity (or specific yield) of th

aquifer (dimensionless);

is the transmissivity of the aquifer (squa

length per time); and

is time.

Inspection of equation 1 indicates that at 

time, the argument of the complementary error 

tion ( ) becomes large, and the function itself 

approaches zero. This indicates that immediatel

Qs Qw = erfc U( )

U d

2

S

4Tt = --------

Qs

Qw

d

S

T

t

U
80 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

withdrawal begins, the source of water to the 

well is aquifer storage, and there is little or no 

streamflow depletion. As time increases, the 

proportion of streamflow depletion contributing water to the well will increase, ultimately 

approaching the rate of withdrawal of the well 

as steady-state conditions are achieved and 

contributions from aquifer storage approach 

zero (that is, as ).

Streamflow depletion consists of two 

components. The first is captured ground-water 

discharge, which is ground water that would 

have discharged to the stream and contributed 

to the total amount of streamflow had the well 

not been pumping. The second component is 

induced infiltration, which is streamflow that is 

drawn out of the stream and into the aquifer. 

The analytical solutions presented here do 

not differentiate between these two components of streamflow depletion, they simply 

provide a total depletion that consists of both 

captured ground-water discharge and induced 

infiltration.

Three of the parameters in equation 1 

that affect streamflow depletion are often 

combined into a single parameter that characterizes a particular stream-aquifer-well system. 

This parameter has been referred to as the 

streamflow depletion factor ( )

 .

The ratio of transmissivity to storativity is 

defined as the hydraulic diffusivity of the aquifer ( ). When a well is located very close to 

a stream (that is, a small ), or when the diffusivity of the aquifer is very large, streamflow 

depletion will begin soon after withdrawal 

begins. Conversely, when a well is located far 

from a stream, or the diffusivity of the aquifer 

is very small (such as occurs for water-table 

aquifers where the storativity, , is assumed 

equal to the specific yield of the aquifer), there 

may be a substantial time lag between when 

the well begins to pump and the beginning of 

streamflow depletion.

Qs Qw = t → ∞

sdf

sdf d

2

S

T = ---------

T S⁄

d

S

The amount of streamflow depletion that occurs 

response to pumping can be reduced by resistance to fl

through streambed and streambank materials at the str

aquifer boundary. In such cases, the streambed and str

bank materials are referred to as being semipervious. H

(1965) derived an analytical solution for streamflow de

by wells that accounts for the presence of semiperviou

rials at the stream-aquifer boundary for the same aqui

stream, and well conditions used to derive equation 1. 

solution is

where

 ,

and , the streambank leakance term (units of length)

defined by

 ,

where

is hydraulic conductivity of the aquifer (length 

time);

is hydraulic conductivity of the streambank (le

per time); and

is thickness of the streambank (length).

As the value of the streambank leakance term 

increases (that is, resistance to flow at the stream-aqui

boundary increases), streamflow depletion responds m

slowly to pumping and streamflow depletion rates are 

than those that would occur in the absence of semiper

streambank materials.

The amount of streamflow depletion that occurs 

response to pumping also can be reduced by partial pe

tion of the stream in the aquifer. The effect of partial p

tion is accounted for in the analytical solutions by rep

the actual distance from the well to the stream ( ) by 

effective distance from the pumped well to the stream

( ). Guidelines for determining are provided by H

(1965) and Spalding and Khaleel (1991). Spalding an

Khaleel show that the effective distance of the well fro

Qs Qw erfc U( ) U2 – ( ) U w+

2 = { } – exp erfc U w [ ] + ( ) +

w

Tt

S

-----

a = --------

a

a Kb'

K' = --------

K

K'

b'

d

x0 x0
Appen

stream is a function of the actual distance from the well 

to the stream and the penetration of the stream into the 

aquifer.

One of the assumptions that was made in the 

development of equations 1 and 2 is that the pumping 

rate of the well is steady during any period of pumping. 

However, the equations can be used in conjunction 

with the method of superposition to calculate streamflow depletion that occurs in response to time-varying 

pumping rates at the well. The use of superposition is 

appropriate here because the underlying ground-water 

flow equation on which each solution is based is linear.

In the superposition approach, incremental 

changes in streamflow depletion that occur in response 

to time-varying pumping rates are accounted for by 

summing the depletions that occur in response to each 

pumping rate. A superposition equation (Stallman, 

1962; Moench, 1971; Butt and McElwee, 1985) can be 

written for total streamflow depletion as

 , (3)

where

is the rate of streamflow depletion at time step i

(cubic length per time);

is the initial pumping rate of the well during 

(cubic length per time);

is the change in pumping rate of the well 

during interval (cubic length per time);

 are the values of either or

(depending on whether equation 1 or 

equation 2 is selected) at times and 

, respectively (dimensionless);

is the length of time from the beginning of 

pumping to the time of interest;

is the time corresponding to time step ;

is the length of time of the initial pumping rate 

prior to the start of the analysis;

is the number of time steps (dimensionless); 

and

is the time step number (dimensionless).

Equation 3 assumes a constant time-step size of 

time unit, such as 1 day. Streamflow depletions 

culated for each time of interest ( ), and each t

interest is equal to the product of the constant tim

size (for example, 1 day) by the number of time 

DESCRIPTION OF COMPUTER 

PROGRAM STRMDEPL

Computer program STRMDEPL was wri

FORTRAN-77 to implement equations 1-3, wh

culate streamflow depletion caused by time-var

pumping at a well. STRMDEPL uses a constan

step size of 1 day; therefore, pumping rates mu

specified for each day of analysis. For example

streamflow depletions are to be calculated for th

year period January 1, 1999 through December 

1999, a total of 365 pumping rates must be spec

the input file, one for each day of the year. Furt

more, the user must specify the value of the init

pumping rate (variable QWINIT) and the length 

time for which that initial pumping rate occurre

to the start of the analysis (variable INTIME). T

values are specified so that the program will cal

an initial, constant streamflow depletion that ac

for the effects of pumping that occurred prior to 

start of the analysis. Streamflow depletions that 

culated for the period of simulation are added to 

tracted from this initial rate of depletion. The in

pumping rate and length of time during which t

pumping rate occurred can be empirically adjus

obtain the desired initial streamflow depletion. 

example, if an initial streamflow depletion equa

previous 12-month average pumping rate was d

the user would specify QWINIT to the average 

ing rate during the previous 12-months and vary 

value of INTIME in a series of simulations unti

initial streamflow depletion was equal (or nearly 

to the 12 month average pumping rate.

The program reads data for a particular si

tion from an input file and writes the results of 

ulation to result and plot files. Line-by-line instr

for creating the input file follow; example input 

program output files are provided in the next se

Variable names that are used in the input file an

puter program are shown in upper-case text. Th

Qs ti ( ) Q0 t

0 ( )F t0 ( ) Qk ∆ t

k ( )F ti k – + 1 ( )

k 1 =

i

= + ∑

Qs ti ( )

Q0 t

0 ( ) t0

Qk ∆ t

k ( )

k

F t0 ( ) F ti k – + 1 , ( ) erfc U( )

erfc U( ) U2 – ( ) U w+

2 { } – exp erfc U w [ ] + ( ) +

t

0

ti k – + 1

ti

t

k k

t

0

i

k

ti
82 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

of each variable (character, integer, or real) is listed 

after the variable’s definition. All data specified in the 

input file are read using free format and all real-valued 

variables are double precision in the program. For 

example, a real-valued variable of 1.33 x 10-3 could be 

entered as 1.33D-3 or as 0.00133. The program is 

designed for specific units for each of the variables; the 

units for each variable are:

Well distance to stream (variable XWELL): feet

Diffusivity of aquifer (variable DIFFUS): square feet 

per second

Streambank leakance term (variable SLEAK): feet

Pumping rates at well (variables QWINIT and 

QWELL): cubic feet per second

Line 1:

TITLE--Title of simulation, which can be up to 70 

characters in length. Leave this line blank if no title 

is specified. (Character variable)

Line 2:

WELLID--An identifier for the well that is being 

simulated, which can be up to 20 characters in 

length. (Character variable)

Line 3:

XWELL--Distance of well to stream, in feet. (Real 

variable)

DIFFUS--Diffusivity of the aquifer, in square feet per 

second. (Real variable)

IBANK--A code that specifies whether or not 

semipervious streambank materials are present. 

(Integer variable)

IBANK = 0: Semipervious streambank materials 

are absent (equation 1 is used)

IBANK = 1: Semipervious streambank materials 

are present (equation 2 is used)

SLEAK--The value of the streambank leakance term, 

in feet, if IBANK = 1. Enter 0.0D0 if IBANK = 0. 

(Real variable)

Line 4: See discussion on these two parameters 

beginning of this section.

INTIME--Number of pumping days prior to sta

analysis. (Integer variable)

QWINIT--Pumping rate prior to start of analysi

cubic feet per second. (Real variable)

Line 5:

NPD--Number of pumping days in analysis. If 

greater than 30,000, parameter IMAXX in 

program STRMDEPL must be increased to 

greater than or equal to NPD and the progra

be recompiled. (Integer variable)

Line 6: Date and pumping rate for each day of 

analysis. Repeat this line of input data NPD tim

CDATE(I)--Date of day I (8 characters, such as 

19990101). (Character variable)

QWELL(I)--Pumping rate for day I, in cubic fe

second. (Real variable)

An example input file for STRMDEPL, w

used in the sample problem described in the nex

tion, is shown in figure 1. Result and plot files c

by STRMDEPL using the input file shown in fi

are given in figures 2 and 3, respectively.

SAMPLE PROBLEM FOR 

IPSWICH RIVER BASIN

The streamflow-depletion program was te

a hypothetical pumped well 486 feet from the r

bank, using pumping rates for Wenham Well 1 

period January 1, 1989 through December 31, 1

(3,287 days). The diffusivity of the aquifer near 

well and river was assumed to be 10,000 square 

per day (0.1157 square feet per second) based o

hydraulic properties of the aquifer in the Ipswic

Basin given in Baker and others (1964) and Sam

and others (1966). The streambed materials are 
Appen

coarse in the vicinity of the well and, accordingly, it 

was assumed that there would be no resistance to flow 

at the streambank caused by semipervious materials. 

As a result, equation 1 was used to calculate streamflow depletions (IBANK = 0). Burns and James (1972) 

also used equation 1 in their analysis of the Ipswich 

River Basin.

An initial streamflow depletion was desired that 

was as close as possible to the pumping rate on January 

1, 1989, which was 0.1903 ft3/s (0.123 Mgal/d). As 

a result, an initial pumping rate of 0.1900 ft3/s (variable QWINIT) and number of pumping days prior to 

the analysis of 10,000 (variable INTIME) were simulated. This combination of initial pumping rate and 

pumping days prior to the start of the analysis (January 

1, 1989) resulted in an initial streamflow depletion of 

0.1848 ft3/s, which is 97.3 percent of the initial pumping rate. The initial streamflow depletion does not 

reach the initial pumping rate of 0.1900 ft3/s, even after 

10,000 days of simulation, because the complementary 

error function in equation 1 asymptotically approaches 

unity. As a result, for this combination of well distance 

from the stream and aquifer diffusivity, it is difficult to 

obtain an initial streamflow depletion equal to the 

initial pumping rate.

Specified daily pumping rates at the well and calculated streamflow depletions in the river for the period 

of analysis are shown in figure 4. As seen in the figure, 

daily pumping rates are quite variable over the period 

of analysis, ranging from 0.0 to about 1.0 ft3/s. The 

pumping rates also show seasonality—generally 

increasing during the spring and summer months and 

decreasing during the fall and winter. Finally, the 

pumping rates show a general trend upward during the 

9-year period. The range and variability of calculated 

streamflow depletion, however, is much less than the 

range and variability of the daily pumping rate, which 

results from the diffusivity of the aquifer and distance 

of the well from the stream. Variability of the daily 

pumping rates is effectively damped by the aquifer, 

which results in a less variable rate of streamflow 

depletion throughout the year. The calculated streamflow depletions also exhibit a general increasing trend 

during the 9-year period of analysis.

REFERENCES

Baker, J.A., Healy, H.G., and Hackett, O.M., 1964, G

and ground-water conditions in the Wilmington

Reading area, Massachusetts: U.S. Geological 

Water-Supply Paper 1694, 80 p.

Burns, A.W., and James, I.C., II, 1972, Computer sim

model of the Ipswich River basin: Massachuset

Resources Commission, Division of Water Res

Ipswich River Watershed District, Publication N

6317, 66 p.

Butt, M.A., and McElwee, C.D., 1985, Aquifer-para

evaluation from variable-rate pumping tests usi

convolution and sensitivity analysis: Ground W

v. 23, no. 2, p. 212–219.

Conover, C.S., 1954, Ground-water conditions in the 

and Mesilla Valleys and adjacent areas in New 

U.S. Geological Survey Water-Supply Paper 12

200 p.

Glover, R.E., 1960, Ground water-surface water 

relationships: Colorado State University paper 

CER60REG45, 8 p.

Glover, R.E., and Balmer, C.G., 1954, River depletio

resulting from pumping a well near a river: Am

Geophysical Union Transactions, v. 35, part 3, 

p. 468–470.

Hantush, M.S., 1964, Hydraulics of wells, in Chow, 

ed., Advances in Hydroscience, v. 1: New York

Academic Press, p. 386.

_____1965, Wells near streams with semipervious b

Journal of Geophysical Research, v. 70, no. 12, 

p. 2829–2838.

_____1967, Depletion of flow in right-angle stream b

steady wells: Water Resources Research, v. 3, n

p. 235–240.

Jenkins, C.T., 1968, Computation of rate and volum

stream depletion by wells: U.S. Geological Sur

Techniques of Water-Resources Investigations, 

chap. D1, book 4, 17 p.

Moench, Allen, 1971, Ground-water fluctuations in r

to arbitrary pumpage: Ground Water, v. 9, no. 2

Newsom, J.M., and Wilson, J.L., 1988, Flow of grou

to a well near a stream--effect of ambient groun

flow direction: Ground Water, v. 26, no. 6, p. 70
84 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

Sammel, E.A., Baker, J.A., and Brackley, R.A., 1966, Water 

resources of the Ipswich River Basin, Massachusetts: 

U.S. Geological Survey Water-Supply Paper 1826, 83 p.

Spalding, C.P., and Khaleel, Raziuddin, 1991, An evaluation 

of analytical solutions to estimate drawdowns and 

stream depletion by wells: Water Resources Research, 

v. 27, no. 4, p. 597–609.

Stallman, R.W., 1962, Variable discharge without vertical 

leakage, in Ferris, J.G., Knowles, D.B., Brown, R.H., 

and Stallman, R.W., Theory of aquifer tests: U.S. 

Geological Survey Water-Supply Paper 1536-E, p. 118–

122.

Theis, C.V., 1941, The effect of a well on the flow of a 

nearby stream: American Geophysical Union 

Transactions, v. 22, part 3, p. 734-738.

Theis, C.V., and Conover, C.S., 1963, Chart for 

determination of the percentage of pumped wat

diverted from a stream or drain, in Bentall, Ray

compiler, Shortcuts and special problems in aq

tests: U.S. Geological Survey Water-Supply Pa

1545-C, p. C106–C109.

Weeks, E.P., and Appel, C.A., 1984, Optimum locat

well near a stream, in Rosenshein, J.S., and Be

G.D., eds., Groundwater hydraulics: Water Res

Monograph Series 9, American Geophysical U

Washington, D.C., p. 4-28.

Wilson, J.L., 1993, Induced infiltration in aquifers w

ambient flow: Water Resources Research, v. 29

p. 3503–3512.
Appen

Depletion for Wenham Well 1

3320000-01G Line 2: WELLID

486.00 0.1157 0 0.0 Line 3: XWELL DIFFUS IBANK SLEAK 

10000 0.1900 Line 4: INTIME QWINIT

3287 Line 5: NPD

19890101 0.1903 Line 6: CDATE(I) QWELL(I)

19890102 0.1864

19890103 0.0982

19890104 0.1470

19890105 0.3133

19890106 0.1377

19890107 0.2754

19890108 0.1648

19890109 0.0897

19890110 0.2352

19890111 0.1857

19890112 0.1818

19890113 0.1748

19890114 0.2011

19890115 0.1230

19890116 0.2769

19890117 0.1122

19890118 0.3056

19890119 0.1973

19890120 0.0982

19890121 0.3644

19890122 0.0967

19890123 0.1253

19890124 0.2143

19890125 0.1849

19890126 0.1601

19890127 0.2066

19890128 0.2004

19890129 0.1942

19890130 0.1578

3,250 lines of input deleted here

19971225 0.1800

19971226 0.2730

19971227 0.2590

19971228 0.1625

19971229 0.2315

19971230 0.2080

19971231 0.2025

Figure 1. Example input file for program STRMDEPL.
86 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

 *****************************************************

 * *

 * **** U.S. GEOLOGICAL SURVEY **** *

 * *

 * *** STRMDEPL: PROGRAM OUTPUT *** *

 * *

 * ONE-DIMENSIONAL MODEL OF STREAMFLOW DEPLETION *

 * *

 * BY WELLS, BASED ON ANALYTICAL SOLUTIONS *

 * *

 * DEVELOPED BY JENKINS (1968) AND HANTUSH (1965) *

 * *

 * VERSION CURRENT AS OF 04/12/99 *

 * *

 *****************************************************

 Depletion for Wenham Well 1 

 SUMMARY OF INPUT DATA

 ---------------------

 WELL IDENTIFIER: 3320000-01G 

 WELL DISTANCE TO STREAM (XWELL): 0.486D+03 feet

 DIFFUSIVITY (DIFFUS): 0.116D+00 square feet per second

 STREAMBANK CODE (IBANK): 0 (semipervious streambank absent)

 INITIAL TIME (INTIME): 10000 days

 INITIAL PUMPING RATE (QWINIT): 0.190D+00 cubic feet per second

 NUMBER OF PUMPING DAYS (NPD): 3287

Figure 2. Example result file generated by program STRMDEPL.
Appen

 RESULTS

 -------

 STREAMFLOW DEPLETION AT BEGINNING OF ANALYSIS:

 0.1848 cubic feet per second

 PUMPING RATE STREAMFLOW DEPLETION

 DAY (cubic feet per second)

 --- ------------ --------------------

 19890101 0.1903 0.1848

 19890102 0.1864 0.1848

 19890103 0.0982 0.1847

 19890104 0.1470 0.1833

 19890105 0.3133 0.1812

 19890106 0.1377 0.1815

 19890107 0.2754 0.1827

 19890108 0.1648 0.1840

 19890109 0.0897 0.1851

 19890110 0.2352 0.1840

 19890111 0.1857 0.1828

 19890112 0.1818 0.1829

 19890113 0.1748 0.1829

 19890114 0.2011 0.1827

 19890115 0.1230 0.1826

 19890116 0.2769 0.1820

 19890117 0.1122 0.1821

 19890118 0.3056 0.1824

 19890119 0.1973 0.1833

 19890120 0.0982 0.1852

 19890121 0.3644 0.1850

 19890122 0.0967 0.1860

 19890123 0.1253 0.1871

 19890124 0.2143 0.1855

 19890125 0.1849 0.1842

 19890126 0.1601 0.1838

 19890127 0.2066 0.1833

 19890128 0.2004 0.1830

 19890129 0.1942 0.1833

 19890130 0.1578 0.1837

 3,250 lines of results deleted here

 19971225 0.1800 0.2375

 19971226 0.2730 0.2371

 19971227 0.2590 0.2373

 19971228 0.1625 0.2385

 19971229 0.2315 0.2388

 19971230 0.2080 0.2382

 19971231 0.2025 0.2379

Figure 2. Example result file generated by program STRMDEPL—Continued.
88 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

 DATE QWELL QS

 19890101 0.1903 0.1848

 19890102 0.1864 0.1848

 19890103 0.0982 0.1847

 19890104 0.1470 0.1833

 19890105 0.3133 0.1812

 19890106 0.1377 0.1815

 19890107 0.2754 0.1827

 19890108 0.1648 0.1840

 19890109 0.0897 0.1851

 19890110 0.2352 0.1840

 19890111 0.1857 0.1828

 19890112 0.1818 0.1829

 19890113 0.1748 0.1829

 19890114 0.2011 0.1827

 19890115 0.1230 0.1826

 19890116 0.2769 0.1820

 19890117 0.1122 0.1821

 19890118 0.3056 0.1824

 19890119 0.1973 0.1833

 19890120 0.0982 0.1852

 19890121 0.3644 0.1850

 19890122 0.0967 0.1860

 19890123 0.1253 0.1871

 19890124 0.2143 0.1855

 19890125 0.1849 0.1842

 19890126 0.1601 0.1838

 19890127 0.2066 0.1833

 19890128 0.2004 0.1830

 19890129 0.1942 0.1833

 19890130 0.1578 0.1837

 3,250 lines of results deleted here

 19971225 0.1800 0.2375

 19971226 0.2730 0.2371

 19971227 0.2590 0.2373

 19971228 0.1625 0.2385

 19971229 0.2315 0.2388

 19971230 0.2080 0.2382

 19971231 0.2025 0.2379

Figure 3. Example plot file generated by program 

STRMDEPL.
Appen

1989 1990 1991 1992 1993 1994 1995 1996 19

0

0.2

PUMPING RATE AND STREAMFLOW DEPLETION,

IN CUBIC FEET PER SECOND

CALCULATED STREAMFLOW DEPLETION

SPECIFIED DAILY PUMPING RATE AT WELL

YEAR

0.4

0.6

0.8

1.0

1.2

EXPLANATION

Figure 4. Specified daily pumping rates at well Wenham Well 1, 1989–97, and calculated streamflow depletion.

APPENDIX B

Ipswich River Watershed Model (HSPF) User Contro

Input File for PERLND and IMPLND Blocks

Appen

*** HSPF model run for Ipswich River Basin, MA 

*** -------------------------------------

*** | Base simulation |

*** -------------------------------------

*** Documentation - HSPF Users manual release 11 (Bicknell and others, 1997)

******************************************************************************

*** PERLND - Pervious land surface Principles 4.2(1).1 pg 37 **

*** Coding 4.4(1) pg 300 **

******************************************************************************

PERLND

 ACTIVITY

 <PLS > Active Sections (1=Active; 0=Inactive) ***

 # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC ***

 1 15 0 1 1

 END ACTIVITY

 PRINT-INFO

 <PLS > <-*** Print-flags: 2-PIVL, 3-dy, 4-mn, 5-yr, 6-never ***-> PIVL P

 # - # ATMP SNOW PWAT SED PST PWG PQAL MSTL PEST NITR PHOS TRAC *

 1 15 5 4 1 

 END PRINT-INFO

 GEN-INFO 

 <PLS ><-------Name------->NBLKS Unit-systems Printer *** 

 ###--### User t-series Engl Metr *** 

 in out *** 

 1 S&G Forest 1 1 1 1 15 0 

 2 S&G Open 1 1 1 1 15 0 

 3 S&G Opn low-resid 1 1 1 1 15 0 

 4 S&G Opn low-res PW 1 1 1 1 15 0 

 5 S&G Opn hi-resid 1 1 1 1 15 0 

 6 S&G Opn hi-res PW 1 1 1 1 15 0 

 7 Open Commercial 1 1 1 1 15 0 

 8 Till Forest 1 1 1 1 15 0 

 9 Till Open 1 1 1 1 15 0 

 10 Till Opn low-resid 1 1 1 1 15 0 

 11 Till Opn low-res PW 1 1 1 1 15 0 

 12 Till Opn hi-resid 1 1 1 1 15 0 

 13 Till Opn hi-res PW 1 1 1 1 15 0 

 14 Fine Dep Forest 1 1 1 1 15 0 

 15 Fine Dep Open 1 1 1 1 15 0 

 END GEN-INFO 

 

*** ------------------------------------------------------------------------ * 

*** PERLND - Section SNOW Principles 4.2(1).2 pg 40 * 

*** Coding 4.4(1).3 pg 309 * 

*** ------------------------------------------------------------------------ * 

 

 ICE-FLAG 

 <PLS > 0= Ice formation not simulated, 1= Simulated *** 

 ### -###ICEFG *** 

 1 15 1 
94 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

 END ICE-FLAG 

 

 SNOW-PARM1 

 <PLS > Snow input info: Part 1 *** 

 ### -### LAT MELEV SHADE SNOWCF COVIND *** 

 1 42. 60. 0.50 1.60 0.25 

 2 42. 60. 0.05 1.60 0.25

 3 7 42. 60. 0.15 1.60 0.25

 8 42. 60. 0.50 1.60 0.25

 9 42. 60. 0.05 1.60 0.25

 10 13 42. 60. 0.15 1.60 0.25 

 14 42. 60. 0.50 1.60 0.25 

 15 42. 60. 0.10 1.65 0.25 

 END SNOW-PARM1 

 

 SNOW-PARM2 

 <PLS > Snow input info: Part 2 *** 

 ### -### RDCSN TSNOW SNOEVP CCFACT MWATER MGMELT *** 

 1 0.15 32. 0.15 0.05 0.90 0.1100

 2 0.15 32. 0.15 0.05 0.90 0.1100

 3 7 0.15 32. 0.20 0.07 1.00 0.1300

 8 0.20 32. 0.15 0.05 0.90 0.1100

 9 0.15 32. 0.15 0.05 0.90 0.1100 

 10 13 0.15 32. 0.20 0.07 1.00 0.1200 

 14 0.15 32. 0.15 0.05 0.90 0.1100 

 15 0.15 32. 0.15 0.05 0.90 0.1100

 END SNOW-PARM2 

 

 SNOW-INIT1 *** 

 <PLS > Initial snow conditions: Part 1 *** 

 ### -### PACKSNOW PACKICE PACKWATER RDENPF DULL PAKTMP *** 

*** 1 15 2.27 0.0 0.49 0.29 35.6 31.6 

 END SNOW-INIT1 *** 

 

 SNOW-INIT2 *** 

 <PLS > Initial snow conditions: Part 2 *** 

 ### -### COVINX XLNMLT SKYCLR *** 

*** 1 15 0.10 0.01 0.15 

 END SNOW-INIT2 *** 

***---------------------------------------------------------------------------

*** PERLND - Section PWATER Princples 4.2(1).3 pg 54 

*** Coding 4.4(1).4 pg 317 

***---------------------------------------------------------------------------

 

 PWAT-PARM1 

*** 1=varies monthly 0=does not

*** <PLS > <PWATER flags><monthly parameter value flags> 

***## -### CSNO RTOP UZFG VCS VUZ VNN VIFW VIRC VLE 

 1 6 1 0 0 1 1 1 1 1 1 

 7 1 0 0 1 1 1 1 1 1 

 8 13 1 0 0 1 1 1 1 1 1 

 14 15 1 0 0 1 1 1 1 1 1 

 END PWAT-PARM1 

 
Appen

 PWAT-PARM2 

 <PLS > *** PWATER input info: Part 2 

 ### -### ***FOREST LZSN INFILT LSUR SLSUR KVARY AGW

 ***(none) (in) (in/hr) (ft) (none) (l/in) (l/i

 1 0.550 14.20 0.286 500. 0.024 0.50 0.9

 2 0.020 14.20 0.287 300. 0.025 0.50 0.9

 3 0.050 11.10 0.242 300. 0.025 0.50 0.9

 4 0.050 11.10 0.242 300. 0.025 0.50 0.9

 5 0.050 10.70 0.212 200. 0.025 0.50 0.9

 6 0.050 10.70 0.212 200. 0.025 0.50 0.9

 7 0.030 8.20 0.080 100. 0.024 0.50 0.9

 

 8 0.550 9.20 0.038 400. 0.026 0.50 0.9

 9 0.020 9.00 0.038 200. 0.028 0.50 0.9

 10 0.050 8.70 0.028 300. 0.026 0.50 0.9

 11 0.050 8.70 0.028 300. 0.026 0.50 0.9

 12 0.050 8.20 0.022 200. 0.026 0.50 0.9

 13 0.050 8.20 0.022 200. 0.026 0.50 0.9

 

 14 0.550 8.70 0.095 300. 0.023 0.50 0.9

 15 0.030 8.70 0.092 200. 0.024 0.50 0.9

 END PWAT-PARM2

 

 

 PWAT-PARM3 

 <PLS > *** PWATER input info: Part 3 

 ### -### ***PETMAX PETMIN INFEXP INFILD DEEPFR BASETP AGWE

 1 15 40. 35. 3.0 1.8 0.00 0.00 0.0

 END PWAT-PARM3 

 

 PWAT-PARM4 

 <PLS > PWATER input info: Part 4 *** 

 Flag PARM1 VCS VUZ VUR VMN VIFW VLE *** 

 ### -### CEPSC UZSN NSUR INTFW IRC LZETP *** 

 (in) (in) (none) (none) (l/da) (none) *** 

 1 0.080 0.28 0.230 1.00 0.75 0.88

 2 0.020 0.22 0.250 1.00 0.75 0.18

 3 0.040 0.16 0.210 1.00 0.75 0.28

 4 0.040 0.16 0.210 1.00 0.75 0.28

 5 0.040 0.16 0.210 1.00 0.75 0.28

 6 0.040 0.16 0.210 1.00 0.75 0.28

 7 0.030 0.12 0.200 1.00 0.75 0.22

 8 0.080 0.22 0.230 1.00 0.75 0.88

 9 0.020 0.19 0.250 1.00 0.75 0.18

 10 0.040 0.14 0.210 1.00 0.75 0.18

 11 0.040 0.14 0.210 1.00 0.75 0.18

 12 0.040 0.14 0.210 1.00 0.75 0.18

 13 0.040 0.14 0.210 1.00 0.75 0.18 

 14 0.080 0.26 0.230 1.00 0.75 0.88

 15 0.020 0.22 0.250 1.00 0.75 0.18

 END PWAT-PARM4 

 
96 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

 MON-INTERCEP 

 Monthly interception storage capacity *** 

 <PLS> Only required if VCSFG=1 in PWAT-PARM1 *** 

 ### -### Interception storage capacity at start of each month *** 

 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC *** 

 1 0.04 0.04 0.04 0.04 0.06 0.12 0.14 0.16 0.17 0.16 0.04 0.04 

 2 0.02 0.02 0.02 0.03 0.03 0.04 0.04 0.04 0.04 0.03 0.02 0.02

 3 7 0.02 0.02 0.02 0.03 0.03 0.05 0.05 0.05 0.05 0.03 0.02 0.02 

 8 0.04 0.04 0.04 0.04 0.05 0.12 0.14 0.16 0.17 0.16 0.04 0.04 

 9 0.02 0.02 0.02 0.03 0.03 0.04 0.04 0.04 0.04 0.03 0.02 0.02

 10 13 0.02 0.02 0.02 0.03 0.03 0.05 0.05 0.05 0.05 0.03 0.02 0.02 

 14 0.04 0.04 0.04 0.04 0.05 0.12 0.14 0.16 0.17 0.16 0.04 0.04 

 15 0.02 0.02 0.02 0.03 0.03 0.04 0.04 0.04 0.04 0.03 0.02 0.02

 END MON-INTERCEP 

 

 MON-UZSN 

 Upper zone nominal storage ***

 UZSN inversly affects peak flow - as UZSN goes up peaks go down ***

 <PLS> Only required if VUZFG=1 in PWAT-PARM1 *** 

 ### -### Upper zone storage at start of each month *** 

 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC *** 

 1 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

 2 6 .77 .77 .77 .77 .77 .77 .77 .77 .77 .77 .77 .77 

 7 .56 .56 .56 .56 .56 .56 .56 .56 .56 .56 .56 .56 

 

 8 .50 .50 .50 .50 .50 .50 .50 .50 .50 .50 .50 .50 

 9 13 .62 .62 .62 .62 .62 .62 .62 .62 .62 .62 .62 .62

 14 15 .60 .60 .60 .60 .60 .60 .60 .60 .60 .60 .60 .60

 END MON-UZSN 

 

 MON-MANNING 

 Manning's "n" for overland flow plans *** 

 <PLS > Only required if VNNFG=1 in PWAT-PARM1 *** 

 ### -### Manning's n for overland flow at start of each month *** 

 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC *** 

 1 0.28 0.28 0.28 0.28 0.29 0.29 0.29 0.29 0.29 0.29 0.28 0.28 

 2 0.25 0.25 0.25 0.25 0.27 0.30 0.30 0.30 0.30 0.27 0.25 0.25 

 3 7 0.22 0.22 0.22 0.22 0.23 0.26 0.26 0.26 0.26 0.25 0.23 0.22 

 

 8 0.28 0.28 0.28 0.28 0.29 0.29 0.29 0.29 0.29 0.29 0.28 0.28 

 9 0.25 0.25 0.25 0.25 0.27 0.30 0.30 0.30 0.30 0.27 0.25 0.25 

 10 13 0.22 0.22 0.22 0.22 0.23 0.26 0.26 0.26 0.26 0.25 0.23 0.22 

 14 0.25 0.25 0.25 0.25 0.27 0.27 0.27 0.27 0.27 0.25 0.25 0.25 

 15 0.25 0.25 0.25 0.25 0.27 0.30 0.30 0.30 0.30 0.27 0.25 0.25 

 END MON-MANNING 

 
Appen

 MON-INTERFLW 

 Monthly interflow parameter *** 

 <PLS > Only required if VIFWFG=1 in PWAT-PARM1 *** 

 ### -### Monthly interflow at start of each month *** 

 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC *** 

 1 8.60 8.60 8.60 8.65 8.65 8.65 8.65 8.65 8.65 8.70 8.70 8.70

 2 8.50 8.50 8.50 8.50 8.55 8.55 8.55 8.55 8.55 8.50 8.50 8.50

 3 7 8.30 8.30 8.30 8.30 8.35 8.35 8.35 8.35 8.35 8.30 8.30 8.30

 8 5.90 5.90 5.90 5.95 5.95 5.95 5.95 5.95 5.95 5.90 5.90 5.90

 9 5.80 5.80 5.80 5.80 5.85 5.85 5.85 5.85 5.85 5.80 5.80 5.80

 10 13 5.70 5.70 5.70 5.70 5.75 5.75 5.75 5.75 5.75 5.70 5.70 5.70

 14 6.50 6.50 6.50 6.55 6.55 6.55 6.55 6.55 6.55 6.50 6.50 6.50

 15 6.40 6.40 6.40 6.40 6.45 6.45 6.45 6.45 6.45 6.40 6.40 6.40

 END MON-INTERFLW 

 MON-IRC 

 Monthly interflow recession *** 

 <PLS > Only required if VIRCFG=1 in PWAT-PARM1 (max < 1.0) *** 

 ### -### Monthly interflow at start of each month *** 

 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC *** 

 1 2 0.90 0.90 0.90 0.90 0.91 0.92 0.92 0.92 0.91 0.90 0.90 0.90 

 3 4 0.88 0.88 0.88 0.88 0.89 0.90 0.90 0.90 0.90 0.88 0.88 0.88

 5 6 0.86 0.86 0.86 0.86 0.87 0.88 0.88 0.88 0.87 0.86 0.86 0.86 

 7 0.82 0.82 0.82 0.82 0.84 0.86 0.86 0.86 0.84 0.82 0.82 0.82 

 8 9 0.90 0.90 0.90 0.90 0.91 0.92 0.92 0.92 0.92 0.90 0.90 0.90 

 10 11 0.88 0.88 0.88 0.88 0.89 0.90 0.90 0.90 0.89 0.88 0.88 0.88

 12 13 0.86 0.86 0.86 0.86 0.87 0.88 0.88 0.88 0.87 0.86 0.86 0.86 

 14 15 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 0.90 

 END MON-IRC 

 

 MON-LZETPARM 

 Lower zone ET *** 

 <PLS > Only required if VLEFG=1 in PWAT-PARM1 (max < 1.0) *** 

 ### -### Lower zone ET parameter at start of each month *** 

 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC *** 

 1 .73 .73 .73 .78 .82 .87 .92 .92 .83 .78 .73 .73 

 2 .18 .18 .20 .22 .24 .26 .27 .27 .22 .21 .20 .18 

 3 6 .40 .40 .40 .42 .44 .50 .54 .54 .52 .44 .42 .40 

 7 .35 .35 .35 .37 .39 .43 .45 .45 .44 .39 .37 .35 

 8 .73 .73 .73 .78 .82 .87 .92 .92 .83 .78 .73 .73 

 9 .18 .18 .20 .22 .24 .26 .27 .27 .22 .21 .20 .18 

 10 13 .40 .40 .40 .42 .44 .50 .54 .54 .52 .44 .42 .40 

 14 .73 .73 .73 .78 .83 .87 .92 .92 .83 .78 .73 .73 

 15 .22 .22 .25 .27 .28 .32 .33 .33 .32 .28 .25 .22 

 END MON-LZETPARM 

 
98 A Precipitation-Runoff Model for Analysis of the Effects of Water Withdrawals on Streamflow, Ipswich River Basin, Massa

 PWAT-STATE1 

 <PLS > *** Initial conditions at start of simulation 

 ### -### *** CEPS SURS UZS IFWS LZS AGWS GWV

 1 0.04 0.00 0.39 0.000 15.62 5.93 1.

 2 0.02 0.00 1.24 0.007 21.08 7.56 1.

 3 6 0.02 0.00 1.07 0.001 14.35 3.05 1.

 7 0.02 0.00 0.91 0.007 10.62 0.99 1.

 8 0.04 0.00 0.76 0.015 10.06 1.41 0.

 9 0.02 0.00 1.23 0.112 12.38 1.69 1.

 10 13 0.02 0.00 1.10 0.040 10.00 1.00 1.

 14 0.04 0.00 0.79 0.002 9.76 1.21 0.

 15 0.02 0.00 1.03 0.003 11.76 1.48 1.

 END PWAT-STATE1 

 

END PERLND 

 

************************************************************************** 

*** IMPLND - Impervious land 4.2(2) Principles 4.2(2) pg 114 *** 

*** Coding 4.4(2) pg 457 *** 

************************************************************************** 

IMPLND 

 ACTIVITY 

 <ILS > Active Sections (1-active, 0-inactive) *** 

 ### -### ATMP SNOW IWAT SLD IWG IQAL *** 

 1 0 1 1 

 2 0 1 1 

 END ACTIVITY 

 

 PRINT-INFO 

 2-PIVL, 3-dy, 4-mn, 5-yr, 6-never user end *** 

 <ILS > <------ Print-flags --------> PIVL PYR *** 

 ### -### ATMP SNOW IWAT SLD IWG IQAL #### ## *** 

 1 4 4 1 12 

 2 4 4 1 12 

 END PRINT-INFO 

 

 GEN-INFO 

 <ILS ><-------Name-------> Unit-systems Printer *** 

 ### -### User t-series Engl Metr *** 

 in out i/o# *** 

 1 Residential 1 1 1 15 0 

 2 Commercial 1 1 1 15 0 

 END GEN-INFO 

*** ------------------------------------------------------------------------* 

*** IMPLND- Same as PERLND Section SNOW * 

*** see 4.4(1).3 pg 309 * 

*** ------------------------------------------------------------------------* 

 
Appen

 ICE-FLAG 

 <PLS > 0= Ice formation not simulated, 1= Simulated *** 

 ### -###ICEFG *** 

 1 2 1 

 END ICE-FLAG 

 

 SNOW-PARM1 

 <PLS > Snow input info: Part 1 *** 

 ### -### LAT MELEV SHADE SNOWCF COVIND *** 

 1 2 42. 60. 0.20 1.80 0.15 

 END SNOW-PARM1 

 

 SNOW-PARM2 

 <PLS > Snow input info: Part 2 *** 

 ### -### RDCSN TSNOW SNOEVP CCFACT MWATER MGMELT *** 

 1 2 0.20 32. 0.02 0.05 1.00 0.1100 

 END SNOW-PARM2 

 

 SNOW-INIT1 *** 

 <PLS > Initial snow conditions: Part 1 *** 

 ### -### PACKSNOW PACKICE PACKWATER RDENPF DULL PAKTMP *** 

*** 1 2 2.2 0.0 0.61 0.29 35. 31.5 

 END SNOW-INIT1 *** 

 

 SNOW-INIT2 *** 

 <PLS > Initial snow conditions: Part 2 *** 

 ### -### COVINX XLNMLT SKYCLR *** 

*** 1 2 0.10 0.01 0.15 

 END SNOW-INIT2 *** 

 

*** ---------------------------------------------------------------------- * 

*** IMPLND - Section IWATER input Principles 4.2(2).3 pg 114 * 

*** Coding 4.4(2).4 pg 464 * 

*** ---------------------------------------------------------------------- * 

 

 IWAT-PARM1 

 <ILS > Flags *** 

 ### -### CSNO RTOP VRS VNN RTLI *** 

 1 1 1 0 

 2 1 1 0 

 END IWAT-PARM1 

 

 IWAT-PARM2 

 <ILS > *** 

 ### -### LSUR SLSUR NSUR RETSC *** 

 1 400. .014 .010 .04 

 2 200. .010 .010 .08 

 END IWAT-PARM2 

 

 IWAT-PARM3 

 <ILS > *** 

 ### -### PETMAX PETMIN *** 

 1 40. 35. 

 2 40. 35. 

 END IWAT-PARM3 

 

END IMPLND