LIDAR Flood mapping for Brownsville and Matamoros Gueudet Pierre GIS in Water Resources University of Texas Austin Fall 2002
Particularity of the region: Frequent Rainfalls (hurricanes + floods) Very flat region (5 to 6 m above sea level) A vast network for irrigation Bonsville/Matamoros
HEC-GeoRas Preprocessing Geometric data stream centerlines, riverbanks, floodplain boundaries, cross- sections along the streams HEC-GeoRas Postprocessing Flow data from HEC-HMS HEC-RAS steady state simulation Hydraulic modeling Hydrologic modeling Flood map visualization Import file ARCVIEW Terrain model processing LIDAR input data 1m grid DEM Procedure:
Terrain model processing I need to : Collect LIDAR data Build a Hydro Network Build a TIN which rivers have a clean cross-sections (problem with bridges)
-Elevation accuracy : 10 to 25 cm - records first and last returns of individual pulses and intensity Applications in : Flood mapping Forest management Land cover classification Atmospheric pollution monitoring First Step: collecting LIDAR data
I don’t have the LIDAR data yet (not available before January) then: I used less precise data (7 m resolution) from the Bureau of Economic Geology. I just obtained LADAR data for a small part of Brownsville and I am going to work on it.
Second step: building an Hydro Network I tried to use Arc Hydro Terrain Processing. I got no useful results because of: the flatness of the region the precision of the data Streams obtained with Arc Hydro Terrain processing Flow direction
Second step: building an Hydro Network Rio Grande River => I am going to work only on the Rio Grande
Third step: terrain processing
Conclusion Work in progress! I am going to start working on HEC-GeoRas and HEC- HMS. I want to use the LIDAR data to see if I can obtain interesting results with Arc Hydro Terrain Processing