Money-Saving Model

by Carson Mettel, Geographic Analysis Manager; Mead & Hunt, Madison, WI,
David McGraw, Mead & Hunt, 6501 Watts Rd., Suite 101, Madison, WI 53719,
Susanne Strater, GIS Consultant; Barnesville, GA,

Serial Information: Civil Engineering—ASCE, 1994, Vol. 64, Issue 1, Pg. 54-56

Document Type: Feature article


Determining whether dams and spillways along a river are adequate to handle potential floods can have far-reaching financial, as well as human ramifications. Watershed modeling studies are traditionally used to evaluate these structures. In 1989, standard modeling on the Au Sable River in Michigan yielded a Probable Maximum Flood between 30,000 and 36,000 cu ft per sec.--higher than the capacity of the dams and spillways. The cost to repair four of the structures was estimated at $18 million. Several factors, however, led hydrologists to believe that the expected PMF values for the river were really much lower than those predicted by the model. Ground cover and soil data--critical variables input to the watershed model--were obtained from out-of-date maps. As a result, engineers sought to refine modeling techniques to reflect more accurately the unique characteristics of the basin. Hydrologists used satellite images and computer models to analyze the basin before the upgrades were started. The PMF calculations were revised to 21,000 cu ft per second and the estimated cost for upgrades to structures along the Au Sable River was ultimately reduced by 90%.

Subject Headings: Hydrologic models | Computer models | Rivers and streams | Drop structures | Dams | Spillways | Floods | Watersheds | Michigan | United States

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