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

Tools Data

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 ResultsDetention Pond

Main Channel

Comparison of Flows

2500 CFS

5000 CFS

Questions ???