Lidar for Mississippi: floods, forests and a falling aquifer

Mississippi has complete statewide lidar — laser-measured 3D elevation — from the U.S. Geological Survey's 3D Elevation Program (3DEP). A national assessment conservatively valued it at $10.41 million a year to the state, led by infrastructure, flood risk and farming.

A low, wet, forested state

Mississippi spreads nearly three million people over about 48,400 square miles of low hills and plains; its highest point is about 800 feet. In the northwest lies the nearly flat Mississippi Alluvial Plain — the Delta. Rain is plentiful and temperatures mild, so agriculture and forestry dominate: 65 percent of the state is forest, and it is one of the country's leading producers of lumber and wood products.

Where it helps

• Groundwater in the Delta. Heavy pumping from the Delta's aquifer has lowered groundwater levels and cut the base flow of its streams, limiting wells and threatening future supply — and the system is poorly understood. The USGS, on the governor's Delta Sustainable Water Resources Task Force, is studying past and present water use to improve forecasts; higher-quality lidar would sharpen the picture.
• Floods and storm surge. Statewide lidar cuts the cost and time of flood studies and improves their accuracy, making it possible to model overflow from big storms, dam failures and Gulf of Mexico storm surge — and to plan evacuation routes before they are needed.
• Forests. The Mississippi Forestry Commission protects the state's forests from fire, pests, disease and invasive species and tracks harvest and regrowth. Along the Natchez Trace Parkway, the Park Service's Gulf Coast Inventory and Monitoring Network compares upward-looking photographs of the canopy with lidar point clouds to judge forest health.

Canopy along the Natchez Trace Parkway, dense at mile 209, sparse at mile 197: photographs against lidar point-cloud density. National Park Service.

The data

The state's quality-level-2 coverage is complete; higher levels can be collected at extra cost. The minimum standard means at least two laser returns per square metre and no more than 10 centimetres of vertical error; the products — point clouds and bare-earth elevation models at 1 metre or finer — are free and unrestricted on The National Map. Nationally, 3DEP is conservatively worth $690 million a year, and partners can join through the USGS's annual Data Collaboration Announcement.

Sources

Written from The 3D Elevation Program—Supporting Mississippi's economy, U.S. Geological Survey Fact Sheet 2024–3027, a work of the United States government in the public domain; benefit estimates are from the National Enhanced Elevation Assessment (Dewberry, 2012).