Enhanced elevation data support critical applications

Flood risk 

management

Infrastructure 

management

Natural 

resources 

conservation

Agriculture 

and precision 

farming

Stream 

resource 

management

Water supply

Wildfire 

management

Aviation safety

Geologic 

resource 

assessment

Forest 

resources 

management

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3088

July 2012

Introduction

Elevation data are essential for 

hazards mitigation, conservation, infra-

structure development, national security, 

and many other applications. Under 

the leadership of the U.S. Geological 

Survey and the National Digital Elevation 

Program (NDEP), Federal agencies, State 

agencies, and others work together to 

acquire high-quality elevation data for 

the United States and its territories. New 

elevation data are acquired using modern 

technology to replace elevation data 

that are, on average, more than 30 years 

old. Through the efforts of the NDEP, 

a project-by-project data acquisition 

approach resulted in improved, publicly 

available data for 28 percent of the 

conterminous United States and 15 percent 

of Alaska over the past 15 years. Although 

the program operates efficiently, the rate 

of data collection and the typical project 

specifications are currently insufficient 

to address the needs of government, the 

private sector, and other organizations.

The National Enhanced Elevation 

Assessment (NEEA; Dewberry, 2011) was 

conducted to (1) document national-level 

requirements for improved elevation 

data, (2) estimate the benefits and costs of 

meeting those requirements, and (3) evalu-

ate multiple national-level programimplementation scenarios. The assessment 

was sponsored by the NDEP’s member 

agencies. The study participants came from 

34 Federal agencies, agencies from all 

50 States, selected local government and 

Tribal offices, and private and not-for-profit 

organizations. A total of 602 missioncritical activities were identified that need 

significantly more accurate data than are 

currently available. The results of the 

assessment indicate that enhanced elevation data have the potential to generate 

$13 billion in new benefits annually. 

Requirements for Enhanced 

Elevation Data

The requirements for elevation data 

were documented as part of the assessment 

through surveys and structured interviews. 

Each requirement was described in terms 

of the accuracy of the data, the data refresh 

cycle, and the geographic area of interest. 

The expected benefits that would result 

from meeting these requirements were also 

identified. To facilitate this analysis, the 

results of the survey and interviews were 

sorted by 27 predefined business uses. 

Table 1 summarizes expected benefits for 

the top 10 of 27 identified business uses, 

in dollar amounts. The dollar amounts 

represent cost savings either for the 

operating agencies or for the customers 

who use their services and are detailed for 

each organization in Dewberry (2011). For 

example, in Alabama, high-quality eleva-

tion data could potentially save the State’s 

Department of Economic and Community 

Affairs $5 million because of the reduced 

time (and thereby costs) needed to create 

datasets for analyzing flood risks. The 

improved data could potentially save the 

agency’s customers $3 million because 

the data would help reduce the costs and 

amount of time required to complete 

certain phases of flood-risk mitigation 

projects. 

For about half of the reported 

applications, the surveyed organiza-

tions were unable to identify specific 

economic benefits even though most 

of them expected major benefits from 

improved elevation data. For example, the 

Environmental Protection Agency needs 

high-accuracy, high-resolution topographic 

data to characterize the landscape for both 

environmental protection and assessment 

of ecosystem services but did not quantify 

the benefits. Narratives describing the 

benefits of improved elevation data 

without associated monetary benefits are 

also included in Dewberry (2011).

Analysis and National Elevation 

Program Scenarios

Benefit-cost analyses were 

developed and examined for more than 

25 program scenarios (Dewberry, 2011), 

which included various quality levels 

for the elevation data (table 2) and datareplacement cycles. The estimated costs 

for each scenario include those for data 

collection and life-cycle management. 

National Enhanced Elevation Assessment

at a Glance
Each scenario would implement a national 

data-collection strategy to achieve cost 

efficiencies and meet the requirements of 

multiple organizations. 

The final analysis yielded 10 leading 

scenarios, which are shown in figure 

1. The least beneficial scenario is one 

that provides national data coverage 

at quality level 3 (see table 2 for more 

information on quality levels) on a 25-year 

replacement schedule but realizes only 

13 percent of the benefits. In contrast, the 

national data coverage at quality level 

1 on an annual replacement schedule 

realizes 98 percent of the conservative 

benefits. The 58-percent mid-range 

scenario offers a good benefit-to-cost ratio, 

uniform quality level 2 data, and an 8-year 

acquisition cycle. All of the scenarios 

included quality level 5 data coverage in 

Alaska, which would be collected by using 

interferometric synthetic aperture radar 

(ifsar) techniques; in Alaska cloud cover 

and remoteness preclude consideration of 

lidar data over much of the State. With the 

exception of the 98-percent scenario, all of 

the scenarios resulted in positive benefitto-cost ratios ranging from 4:1 to 5:1 using 

the most conservative benefit estimates. 

The NEEA also reviewed current 

and emerging commercial elevation-data 

technologies, assessed data life-cyclemanagement costs for the various 

scenarios, and produced an inventory of 

existing elevation data derived from lidar 

and ifsar datasets. The inventory revealed 

that about 28 percent of the conterminous 

United States is covered by quality level 3 

lidar data and that about 15 percent of 

Alaska is covered by ifsar data. 

Summary

The current NDEP activity is a 

partnership between Federal, State, and 

other agencies. Although the effort is 

efficient (very little duplication of effort), 

the program currently meets less than 

10 percent of the needs identified in the 

NEEA. The following are the major 

findings:

1. Significant benefits could be realized by 

systematically upgrading the Nation’s 

elevation data. Hundreds of improved 

business applications would benefit 

all levels of government and multiple 

industries. 

2. The developed program scenarios demonstrated that favorable benefit-to-cost 

ratios can be achieved by integrating 

multiple requirements in large projects. 

3. A new information technology infrastructure is needed for a project of this 

scale. 

4. Current elevation technologies, 

industry capacity, data standards, and 

related matters are sufficient; there are 

Table 2. Data quality levels used in the 

National Enhanced Elevation Assessment.

[≤, less than or equal to]

Quality 

level

Horizontal 

point spacing 

(meters)

Vertical accuracy 

(centimeters)

1 0.35 9.25

2 0.7 9.25

3 1–2 ≤ 18.5

4 5 46–139

5 5 93–185

no capability constraints or technical 

barriers precluding a national program 

and no technical reasons to delay its 

implementation. 

5. The majority of applications now require 

data better than quality level 3.

Reference Cited

Dewberry, 2011, Final Report of the National 

Enhanced Elevation Assessment: Fairfax, 

Va., Dewberry, 84 p. plus appendixes 

(revised 2012), available at http://www.

dewberry.com/Consultants/Geospatial

Mapping/FinalReport-National

EnhancedElevationAssessment.

Partners

The NEEA was conducted under a contract between the U.S. Geological Survey and 

Dewberry (a consulting firm based in Fairfax, 

Va.). Additional support for the assessment 

came from other Federal agencies: the Federal 

Emergency Management Agency, the National 

Geospatial-Intelligence Agency, the National 

Oceanic and Atmospheric Administration, and 

the Natural Resources Conservation Service.

For Further Information

More information on the NEEA may be 

found at http://nationalmap.gov/3DEP/

neea.html, or by contacting the author at 

gsnyder@usgs.gov or (703) 648–5169.

By Gregory I. Snyder

2,000

1,800

1,600

1,400

1,200

1,000

800

600

400

200

0

Dollars, in millions

Annual costs

Annual total benefits

Needs satisfied by scenario, in percent

98 71 66 59 58 33 30 30 22 13

EXPLANATION

Figure 1. The 

10 leading program 

scenarios resulting 

from the National 

Enhanced Elevation 

Assessment showing 

annual costs and total 

benefits.

Table 1. Annual aggregated monetary benefits for the top 10 business uses identified in the 

National Enhanced Elevation Assessment.

[Benefits were reported as single values or as a range of values in the assessment report (Dewberry, 2011). Only one 

half of participants were able to assign benefits to their activities, and the conservative benefits include these numbers 

only. Further, when benefits were reported as a range, only the low end of the range was included in calculating 

conservative benefits. Potential benefits were based on the high end of benefit ranges and included some estimated and 

projected benefits as well as the benefits expected from some emerging applications]

Rank Business use

Annual benefits

Conservative 

(in millions of 

dollars)

Potential 

(in millions of 

dollars)

1 Flood risk management $295 $502

2 Infrastructure and construction management 206 942

3 Natural resources conservation 159 335

4 Agriculture and precision farming 122 2,011

5 Water supply and quality 85 156

6 Wildfire management, planning, and response 76 159

7 Geologic resource assessment and hazard mitigation 52 1,067

8 Forest resources management 44 62

9 River and stream resource management 38 87

10 Aviation navigation and safety 35 56