by David M. Beekman and Vito A. Cimino Experience of Flood Analysis in the Ohio River Basin Using ArcView GIS for HEC-RAS Flow Computation by David M. Beekman and Vito A. Cimino Co-authored by Dr. Tiao Chang Department of Civil Engineering, Ohio University Terri Dawson, Coy Miller, Jerry Web US Army Corps of Engineers, Water Resources Engineering

Objectives Generate channel cross sections using HEC-2 data Convert existing HEC-2 data to HEC-RAS Geo-Reference data using ArcView GIS Present Inundation Mapping

Project Location Alum Creek

What’s Required? Existing HEC-2 data for desired reach USGS 1:24,000 DLG data Software HEC-RAS ArcView GIS

Procedure Outline Spatial Data Management Cross Section Generation Pre-processing Hydraulic Flow Computations Final DEM Production Post-processing Final Inundation Map Production

Spatial Data Management Download USGS 1:24,000 DLGs Hypsography Hydrography Roads Convert to shapefiles in ArcView Delineate stream centerline and banks

Cross Section Generation Analysis of HEC-2 Data Cross section lengths Distance between adjacent cross sections Cross section elevations

Cross Section Generation (cont.) Application of ArcView Constructed manually Based on topography and cross section survey data Cross section stationing and distance calculations (use of AVRAS 2.2 – ArcView extension)

Geo-Referenced Cross Sections

Pre-processing Preparation of temporary terrain TIN USGS hypsography DLGs Implement AV-RAS options in ArcView (use of AVRAS 2.2 – ArcView extension)

Pre-processing (cont.) Select AV-RAS theme setup TIN Cross sections Centerline Banks Flow path

Pre-processing (cont.) Complete remaining AV-RAS options Generate *.geo file Import file for HEC-RAS Consists of ArcView geometric data

HEC-2 X-sections Preprocessed X-sections

Hydraulic Flow Computation Adjust GIS geometry file according to HEC-2 data in HEC-RAS Ground elevations Cross section lengths

Hydraulic Flow Computation Adding parameters Manning’s‘n’ values Contraction/Expansion coefficients Bridges/Piers Steady flow data Run water surface profile computations Model verification Generate *.gis file (HEC-RAS export file)

Final DEM Production Run Avenue script to export cross sections into ArcView Cross section and point elevation shapefiles generated Based on HEC-RAS geometry data Point elevation data (original HEC-2 data) Topographical elevation data (USGS data) Final DEM produced

Final DEM

Post-processing Implement RAS-AV options in ArcView (use of AVRAS 2.2 – ArcView extension)

Post-processing (cont.) Select RAS-AV theme setup HEC-RAS *.gis export file Creation of output directory Terrain TIN Rasterization cell

Post-processing (cont.) Complete remaining RAS-AV options Select desired water surface elevations Floodplain delineation

Alum Creek Floodplain 4,200 cfs 6,500 cfs 8,100 cfs 13,600 cfs

Final Inundation Mapping 4,200 cfs

Final Inundation Mapping 6,500 cfs

Final Inundation Mapping 8,100 cfs

Final Inundation Mapping 13,600 cfs

Conclusions Converted HEC-2 data to HEC-RAS Created cross sections to geographically reference HEC-2 data with ArcView GIS Performed hydraulic flow analysis with HEC-RAS Presented Inundation Mapping for floodplain delineation

U.S. Army Corps of Engineers, Huntington District Acknowledgements Ohio University U.S. Army Corps of Engineers, Huntington District

Questions?