LWI Region 3 Modeling Overview

3.3.1 LiDAR Data Summary for Region 3 Modeling OVERVIEW 3.3 LiDAR LiDAR acquisition, DEM correction, bathymetric enhancements, modification.

REGION 3 LIDAR DATA { Acquired in 2021–2022 in two phases: • Catahoula-Concordia 1 and 2 (Figure 3-5) • Northeastern 1, 2, and 4 ( Figure 3-6) { Acquisition was not temporally consistent , requiring blending of datasets. LEARN MORE: T_APPENDIX 4 + { The northeastern corner of Louisiana remains without finalized USGS-approved LiDAR (Figure 3-7).

{ LiDAR captures detailed three-dimensional (3D) elevation data using laser pulses from aircraft or drones. { Raw data is processed to remove noise, align sensors, and filter vegetation and structures. { Digital elevation models (DEMs) are created from ground points and serve as the base for hydraulic and hydrologic modeling.

USGS 3DEP Lidar Explorer

• Preliminary data did not meet USGS quality standards. • Key watersheds— Boeuf, Macon, and Tensas — depend on this data. • Extensive corrections were needed to improve data usability for modeling.

Figure 3-5: Extent of the Catahoula-Concordia LiDAR data relevant to modeling Region 3.

Figure 3-6: Extent of the Northeast LiDAR data relevant to modeling Region 3.

3.3.2 Key Data Issues

{ Limited hydro-flattening. { LiDAR processing agency only flattened rivers wider than 100 feet (ft). { Smaller channels were excluded, causing elevated or sloped features in the DEM. INCONSISTENT APPLICATION { Even qualifying streams had variable width and depth flattening. { Inconsistencies resulted in terrain discontinuities affecting flow paths ( Figure 3-8). HIGH WATER ACQUISITION

Figure 3-7: USGS LiDAR product, Catahoula-Concordia and Northeastern data relevant to modeling Region 3.

{ Some data was captured during flooding events. { Elevated water surfaces obscured true ground features, complicating channel and floodplain delineation ( Figure 3-9).

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LWI REGION 3 TRAINING

LOUISIANA WATERSHED INITIATIVE