3DEP in South Carolina by the Numbers

Expected annual benefits $4.30 million 

Estimated total cost $10.36 million

Payback 2.4 years

Quality level 1 buy-up 

estimate

$6.59 million

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2015–3029

April 2015

The 3D Elevation Program—Summary for South Carolina

Introduction

Elevation data are essential to a broad 

range of applications, including forest 

resources management, wildlife and habitat 

management, national security, recreation, 

and many others. For the State of South 

Carolina, elevation data are critical for flood 

risk management, natural resources conservation, agriculture and precision farming, 

infrastructure and construction management, 

forest resources management, and other business uses. Today, high-density light detection 

and ranging (lidar) data are the primary 

sources for deriving elevation models and 

other datasets. Federal, State, Tribal, and local 

agencies work in partnership to (1) replace 

data that are older and of lower quality and 

(2) provide coverage where publicly accessible data do not exist. A joint goal of State 

and Federal partners is to acquire consistent, 

statewide coverage to support existing and 

emerging applications enabled by lidar data. 

The National Enhanced Elevation 

Assessment (NEEA; Dewberry, 2011) 

evaluated multiple elevation data acquisition 

options to determine the optimal data quality 

and data replacement cycle relative to cost to 

meet the identified requirements of the user 

community. The evaluation demonstrated that 

lidar acquisition at quality level 2 (table 1) for 

the conterminous United States and quality level 5 interferometric synthetic aperture 

radar (ifsar) data (table 1) for Alaska with a 

6- to 10-year acquisition cycle provided the 

highest benefit/cost ratios. The 3D Elevation 

Program (3DEP) initiative (Snyder, 2012a,b) 

selected an 8-year acquisition cycle for the 

respective quality levels. 3DEP, managed 

by the U.S. Geological Survey (USGS), the 

Office of Management and Budget Circular 

A–16 lead agency for terrestrial elevation 

data, responds to the growing need for highquality topographic data and a wide range 

of other 3D representations of the Nation’s 

natural and constructed features.

3D Elevation Program Benefits 

for South Carolina

The top 10 South Carolina business 

uses for 3D elevation data, which are based 

on the estimated annual conservative benefits 

of the 3DEP initiative, are shown in table 2. 

The NEEA survey respondents in the State 

of South Carolina estimated that the national 

3DEP initiative would result in at least 

$4.3 million in new benefits annually to the 

State. The cost for such a program in South 

Carolina is approximately $10.4 million, 

resulting in a payback period of 2.4 years and 

a benefit/cost ratio of 3.3 to 1 over an 8-year 

period. Because monetary estimates were not 

provided for all reported benefits, the total 

benefits of the 3DEP to South Carolina are 

likely much higher. On the basis of the NEEA 

survey results, all levels of government 

and many organizations in South Carolina 

could benefit from access to statewide highresolution elevation data.

For South Carolina, approximately 

73 percent of the identified business use 

requirements will be met in flood risk 

management, natural resources conservation, 

and agriculture and precision farming uses, 

as shown in table 2. The status of publicly 

available lidar data in South Carolina is 

shown in figure 1. By enhancing coordination 

between 3DEP and various government and 

private organizations in South Carolina, it 

may be possible to realize more than the cited 

3D Elevation Program

3DEP is a national program managed 

by the USGS to acquire high-resolution 

elevation data. The initiative is backed by a 

comprehensive assessment of requirements 

(Dewberry, 2011) and is in the early stages 

of implementation. 3DEP will improve data 

accuracy and provide more current data 

than is available in the National Elevation 

Dataset (NED). The goal of this highpriority cooperative program is to have 

complete coverage of the United States 

by the end of 2022, depending on funding 

and partnerships. 3DEP can conservatively 

provide new benefits of $1.2 billion/year 

and has the potential to generate $13 billion/year in new benefits through improved 

government services, reductions in crop 

and homeowner losses resulting from 

floods, more efficient routing of vehicles, 

and a host of other government, corporate, 

and citizen activities (Dewberry, 2011). A 

shared, common elevation dataset would 

foster cooperation and improve decisionmaking among all levels of government and 

other stakeholders.

Benefits of a Funded National Program

• Economy of scale—Acquisition of 

data covering larger areas reduces 

costs by 25 percent.

• A systematic plan—Acquisition of 

data at a higher quality level reduces 

the cost of “buying up” to the highest 

levels needed by State and local 

governments.

• Higher quality data and national 

coverage—Ensure consistency for 

applications that span State and watershed boundaries and meet more needs, 

which results in increased benefits 

to citizens.

• Increase in Federal agency contributions—Reduces State and local partner 

contributions.

• Acquisition assistance—Provided 

through readily available contracts and 

published acquisition specifications.

EXPLANATION

Quality level 2 or 

better data

Quality level 3 data

0 50 Kilometers 25

0 20 40 Miles

Figure 1. Map of South Carolina 

showing publicly available lidar data. 

Information source is the United States 

Interagency Elevation Inventory, 

October 2014 (http://coast.noaa.gov/

inventory/?redirect=301ocm#), which is 

updated annually. Quality level 2 or better 

data meet 3DEP requirements. See table 1 

for quality level information. 
EXPLANATION

0 to 1

>1 to 3

>3 to 6

>6 to 9

>9 to 12

>12 to 15

>15 to 18

>18 to 21

>21 to 24

Depth, in feet

A 02162500 B 02162500

Next Steps for Implementing 3DEP

Accomplishing the 3DEP initiative’s 

goal of national coverage in 8 years depends 

on the following factors:

• Increased partnerships among Federal, 

State, Tribal, and local governments. 

• Partnerships that acquire elevation data 

to the program’s specifications across 

larger project areas.

• Increased communication about and 

awareness of the program’s benefits 

and goals.

• Support for the program from government and other stakeholders.

For Further Information:

Michael A. Tischler, Director

USGS National Geospatial Program

12201 Sunrise Valley Drive, MS 511

Reston, VA 20192

Email: 3DEP@usgs.gov

Gary L. Merrill 

The National Map Liaison

720 Gracern Road, MS 509

Columbia, SC 29210

Email: glmerrill@usgs.gov

http://nationalmap.gov/3DEP/

By William J. Carswell, Jr.

conservative benefits and attain the higher 

potential benefits for many business uses.

The following examples highlight how 

3DEP data can support business uses in South 

Carolina: (1) Lidar data provide high-quality 

terrain information as input for more accurate 

and less expensive hydrologic and hydraulic 

modeling for flood studies; the design of 

structures such as bridges and culverts that 

can safely accommodate runoff and flooding 

from large rain events; and retention dam 

design, dam breach studies, and stormwater 

management and engineering projects. Lidar 

data also aid the identification of vulnerable 

properties within a floodplain, facilitating 

better floodplain-management decisions and 

education of the public on true flood risks 

(fig. 2). Dynamic 3D models that include 

lidar data provide more detailed information on the potential effects of flooding. 

(2) Enhanced elevation data could enable 

State, regional, Tribal, and local governments 

to more effectively implement natural 

resources conservation practices while providing additional cost savings to the public. If 

lidar data were available, public and private 

organizations would expand their use of lidar 

for planning and site-level engineering to 

reduce field work for conservation ponds, 

grassed waterways, pipelines, terracing, accurately calculating runoff, identifying historic 

wetlands (drained), and wetland restoration.

References Cited

Dewberry, 2011, Final report of the National 

Enhanced Elevation Assessment (revised 

2012): Fairfax, Va., Dewberry, 84 p. 

plus appendixes, http://www.dewberry.

com/Consultants/GeospatialMapping/

FinalReport-NationalEnhancedElevation

Assessment.

Snyder, G.I., 2012a, National Enhanced 

Elevation Assessment at a glance: U.S. 

Geological Survey Fact Sheet 2012–3088, 

2 p., http://pubs.usgs.gov/fs/2012/3088/.

Snyder, G.I., 2012b, The 3D Elevation 

Program—Summary of program 

direction: U.S. Geological Survey 

Fact Sheet 2012–3089, 2 p., http://

pubs.usgs.gov/fs/2012/3089/.

ISSN 2327-6932 (online)

http://dx.doi.org/10.3133/fs20153029

3D Elevation Program—Continued

The USGS and its partners will 

acquire quality level 2 or better (table 1) 

3D lidar data over the conterminous United 

States, Hawaii, and the U.S. territories. 

Interferometric synthetic aperture radar 

(ifsar) data are being collected at quality 

level 5 (table 1) in Alaska. The data will 

be acquired over an 8-year period and 

will be made available to the public. By 

using this acquisition scenario a number of 

high-quality elevation-data products can be 

created to serve a wide range of business 

uses in government and the private sector.

Figure 2. A lidar-derived digital 

elevation model was used to 

aid in hydraulic modeling to 

determine flood-inundation 

maps for a 3.95-mile reach of 

the Saluda River, originating 

approximately 150 feet 

downstream from Saluda Lake 

Dam near Greenville, South 

Carolina. Inundation depicted 

corresponds to river stages of 

20.0 feet, A, and 6.0 feet, B, at 

U.S. Geological Survey 

streamgage 02162500, Saluda 

River, near Greenville.

Table 2. Conservative benefits estimates for the top 10 business uses of the proposed 

3DEP data identified in the National Enhanced Elevation Assessment for South Carolina

 (Dewberry, 2011).

Rank Business use Annual benefits

(millions)

1 Flood risk management $1.49

2 Natural resources conservation 1.08

3 Agriculture and precision farming 0.58

4 Infrastructure and construction management 0.41

5 Forest resources management 0.26

6 Coastal zone management 0.16

7 Sea level rise and subsidence 0.15

8 Aviation navigation and safety 0.08

9 Geologic resource assessment and hazard mitigation 0.06

10 Renewable energy resources 0.01

Other 0.02

Total 4.30

Table 1. Data quality levels and related 

accuracies for the 3D Elevation Program 

(3DEP) initiative as provided on page 6 in 

USGS Circular 1399 (http://dx.doi.org/10.3133/

cir1399 ). These data quality parameters for 

the 3DEP initiative approximate those used in 

the National Enhanced Elevation Assessment 

(Dewberry, 2011).

[RMSE(z), root mean square error in the z

(elevation) dimension; n/a, not applicable]

Quality 

level

Nominal pulse 

spacing

(meters)

Vertical error 

as RMSE(z)

(centimeters)

1 0.35 10

2 0.7 10

3 1.4 20

4 n/a 139

5 n/a 185