Floodplain Analysis Floodplain Analysis with ArcGIS Model with ArcGIS Model

BuilderBuilder

Donghyun RimDonghyun RimUniversity of Texas at AustinUniversity of Texas at Austin

What is floodplain and why What is floodplain and why is it important?is it important?

Floodplain - the lowland adjacent to a river, Floodplain - the lowland adjacent to a river, lake or ocean.  lake or ocean.  

Floodplains are designated by the frequency of Floodplains are designated by the frequency of the flood that is large enough to cover them.the flood that is large enough to cover them.

The National Flood Insurance Program has The National Flood Insurance Program has established a minimum standard of protection established a minimum standard of protection against the 100-year flood. against the 100-year flood.

Flood damage reduction – critical interestFlood damage reduction – critical interest

Work SiteWork Site

Austin

Waller Creek

Conceptual ProcessConceptual Process1.1. Rainfall input Rainfall input

2.2. Topologic dataset of the Topologic dataset of the watershed of Waller Creekwatershed of Waller Creek

3.3. Runoff Simulation by using Runoff Simulation by using HEC-HMSHEC-HMS

4.4. Calculation of water Calculation of water surface-elevations along the surface-elevations along the channel with HEC-RASchannel with HEC-RAS

5.5. Transformation of water-Transformation of water-surface elevation to a surface elevation to a unique inundation area unique inundation area known as flood plain known as flood plain

Marvelous Toolbox-Marvelous Toolbox-MAP2MAPMAP2MAP

Developed by Oscar Robayo

Rainfall Map to Flood Rainfall Map to Flood Inundation MapInundation Map

Import into Geodatabase

NEXRAD Rainfall Data

Transfer Data from NEXRAD Cell to

Subbasins

Export Timeseries of Rainfall to HEC-DSS HEC-HMS Streamflow

Hydrographs

Runoff Data (HEC-DSS) to

GIS HEC-RAS

Water Surface Elevation File

Import to GIS as XML Format

Convert WSE to WS TIN

Polygon as Inundated Area

Data CollectionData Collection

1. NEXRAD Rainfall Data 2. Topological Hydrography

3. HEC-HMS 4. HEC-RAS

5.DEM 6. Orthographic Photo6. Orthographic Photo

Creation of Compatible Creation of Compatible DataData

Result for Rosillo CreekResult for Rosillo Creek

Future WorkFuture Work

Use of 10 m cell DEM for delineation Use of 10 m cell DEM for delineation of Watershed.of Watershed.

Perform Map2Map run for Waller Perform Map2Map run for Waller Creek.Creek.

Use of rainfall for another time Use of rainfall for another time periodperiod

Special thanks toSpecial thanks to

Dr. MaidmentDr. Maidment Oscar RobayoOscar Robayo Laton CarrLaton Carr