The 3D Elevation Program: summary for Louisiana

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 Louisiana, elevation data are critical for flood risk management, natural resources conservation, agriculture and precision farming, infrastructure and construction management, water supply and quality, 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 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 high-quality topographic data and a wide range of other 3D representations of the Nation’s natural and constructed features.

3DEP in Louisiana by the Numbers 3D Elevation Program Benefits for Louisiana

Figure 1. Map of Louisiana showing the extent of existing and planned publicly available lidar data. Information source: United States Interagency Elevation Inventory, August 2013, updated annually. No data that meet 3DEP requirements for quality level 2 or better are publicly available in Louisiana. See table 1 for quality level information.

The top 10 Louisiana 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 Louisiana estimated that the national 3DEP initiative would result in at least $6.96 million in new benefits annually to the State. The cost for such a program in Louisiana is approximately $15.6 million, resulting in a payback period of 2.2 years and a benefit/cost ratio of 3.6 to 1 over an 8-year period. Because monetary estimates were not provided for all reported benefits, the total benefits of the 3DEP to Louisiana are likely much higher. On the basis of the NEEA survey results, all levels of government and many organizations in Louisiana could benefit from access to statewide high-resolution elevation data.

For Louisiana, approximately 82 percent of the identified business use requirements will be met in flood risk management, natural resources conservation, agriculture and precision farming, and infrastructure and construction management uses, as shown in table 2. The status of publicly available lidar data in Louisiana is shown in figure 1. By enhancing coordination between 3DEP and various government and private organizations in

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 high-priority cooperative program is to be operational by January 2015, and 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.

Louisiana, it may be possible to realize more than the cited conservative benefits and attain the higher potential benefits for many business uses.

The following examples highlight how 3DEP data can support business uses in Louisiana: (1) Flood protection in southern Louisiana is primarily dependent on earthen levees; following Hurricane Katrina, the State’s levee system received substantial scrutiny. Recent State mandates require levee districts and parish levee managers to survey and assess the levee system every 3 to 5 years and perform a visual inspection every year. A recent study in the Atchafalaya River basin demonstrated that high-resolution digital elevation models derived from airborne lidar surveys can be used to obtain several levee geometric characteristics: levee crest elevation, crown width, levee total width, volume, side slope angles, and full width at half maximum elevation. (2) The vulnerability of human populations and infrastructure to projected increases in sea level is a critical area of uncertainty for communities in the extremely low-lying and flat northern Gulf of Mexico coastal zone. Because elevation is the primary factor that determines the vulnerability of coastal regions to inundation from sea-level rise, high-resolution, accurate digital elevation models that rely heavily on airborne lidar are needed. A recent study

designated the coastal zone areas vulnerable to a 1-meter sea-level rise and applied a coastal economic vulnerability index (CEVI), which includes both physical and economic factors that contribute to societal risks from rising sea level. The model, which highlights areas where human populations and the built environment are most at risk (fig. 2), can be used by coastal managers as they allocate limited resources for ecosystem restoration, beach nourishment, and coastal-protection infrastructure.

References Cited 3D Elevation Program—Continued

Table 1. Data quality levels used in the

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.

For Further Information:

Mark DeMulder, Director, USGS National Geospatial Program 12201 Sunrise Valley Drive, MS 511 Reston, VA 20192 Email: mdemulder@usgs.gov

Christopher Cretini, USGS Geospatial Liaison 700 Cajundome Blvd Lafayette, LA 70506 Email: cretinic@usgs.gov http://nationalmap.gov/3DEP/

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