Application of GIS Tools for Hydraulic Modeling

Overview Introduction to floodplain mapping Why use GIS? Problems Tools and Data Process Results Future Questions

Floodplain Mapping Process Gather Data Hydrologic Analysis Hydraulic Analysis Map Floodplain Using Outputs and Base Maps

Why Use GIS? Delineation of watershed boundaries and parameter estimation is simplified Input of topographic data far less labor intensive Import and Export of data between ArcView and HEC-HMS and HEC-RAS is convenient Amount of labor associated with hand delineation makes adjustments cost-prohibitive

Problems of GIS Gathering data sufficiently accurate for terrain modeling Significant processing time due to size of datasets Matching datasets with different projections

GIS Tools and Data Required Spatial Analyst 3-D Analyst HEC-GeoRAS HEC-RAS 3.0 Triangulated Irregular Network of Clear Creek

3-D Analyst Extension

3-D Analyst Extension

Hydrologic Analysis Calculate Parameters Enter into HEC-HMS Get Flow Data for Later Use in HEC-RAS

Process Load GeoRAS Extension for ArcView

Terrain Model Generate TIN

Terrain Model Create Contours

Hydraulic Process Identify Channel Centerline

Hydraulic Process Draw Right and Left Banks

Hydraulic Process Draw Flowpaths for Channel and Overbanks

Hydraulic Process Insert Desired Cross Section Lines

Hydraulic Process Curves in Stream Calculated using Flowpaths

Prepare GIS Data for Export HEC-GeoRas Theme Setup

Creating RAS/GIS Import File Stream/Reach Names Stationing Bank Stations Reach Names Manning’s ‘n’ Values Cross Section Elevations

Importing GeoRAS Data Create New HEC-RAS Project Import GIS Geometry Data

Using HEC-RAS Add data for hydraulic structures Add roughness values Input flow data View results Export back to GIS

Create Flow Depth Grid

Analyze Results Detention Pond Main Channel

Comparison of Flows 5000 CFS 2500 CFS

Questions ???