GIS for Faster Analysis of Dam-Break Flows

Steve PitmanGIS in Water Resources – Fall 2003

Dr. David Maidment – UT Austin

The Problem:• A breached dam releases

large volumes of water very rapidly

• Can’t predict dam-break floods using observations of natural floods

• Existing dam-break models– Complex, tricky and time

consuming– Not conducive to rapid

analysis

Dams in the U.S.• Approx. 77,000 total• Consider a worst case

scenario: On the Colorado River, Glen Canyon Dam and Hoover Dam, 370 miles apart, created Lake Powell and Lake Mead with combined storage equal to roughly four times the river’s annual flow.

USBR Photo

USBR PhotoLake Powell

What would this water do if rapidly released?

Teton Dam, Idaho – June 5, 1976Teton Dam, Idaho – present day

GIS in Dam-Break Analysis Today• Pacific Disaster Center

uses the M2M interface to translates FLDWAV output for display in ArcGIS

• NWS developing FLDWAV-GIS link for displaying flood predictions

• PBS&J (FEMA Contractor) has fielded a Watershed Analyst extension that automates pre- and post-processing of watershed modeling data

Current Dam-Break Models• DWOPER & DAMBRK developed by

National Weather Service (NWS) in 1970’s• NWS released FLDWAV in 1990’s

– Combined DWOPER & DAMBRK– Added functionality

Input:Dam

parametersValley

geometry

Output:Flow rates &

depths at selected locations

Estimate breach

characteristics•Geometry

•Formation time

Outflow Hydrograph

Flood Routing

Finite-difference solution of

dynamic wave equations

Adding Automation with GIS

Input:Dam

parametersValley

geometry

Output:Flow rates &

depths at selected locations

Estimate breach

characteristics•Geometry

•Formation time

Outflow Hydrograph

Flood Routing

Finite-difference solution of

dynamic wave equations

Geodatabase

GIS

Geospatial data Time Series data

Interface Data ModelPre-Processing Post-Processing

Example

USGS – The National Map

Resources• Applied Hydrology, Chow et al, McGraw Hill (1988)• U.S. Geological Survey websites• U.S. Bureau of Reclamation websites• National Inventory of Dams, U.S. Army Corps of

Engineers• Arc Hydro, Maidment, ESRI Press (2002)• Source of photos