Floods and Flooding
    The Flood of 1993 was the costliest, most devastating flood in U.S. history according to the U.S. Geological Survey. Floodwaters covered as many as 23 million acres of agricultural and urban lands in the Upper Midwest for weeks. The unusual duration and magnitude of this event was triggered by a wet-weather pattern that had persisted since early in the year, followed by a series of intense rainstorms in late June and July. Iowa found itself in the center of the catastrophic flooding that resulted ( U.S.G.S.).

    In the image in the upper right (see U.S.G.S. reference above) floodwaters from the Des Moines River (background) turn Interstate 80 into a causeway connecting remaining segments of dry land in this July 12, 1993 event.

    This presentation will lead you through several topics:

    1. stream discharge,
    2. flooding history, and
    3. flood prediction.

      These exercises were designed so that you will have the background needed to proceed to the Simonton, TX case history.

    4. Case History : Simonton, Texas Has A Problem

    Where To Go From Here

    1. What is a Recurrence Interval?
    2. How can we have two "100-Year Floods" in less than two years?
    3. How can the same stream flow be a 100-Year flood at one location and only a 50-Year flood at another?

    Produced by:

      William R. Dupre'
      John C. Butler
      Ian Evans

      Department of Geosciences
      University of Houston
      Houston, Texas 77204
      January, 2001