WHAT THE CORPS LEARNED FROM THE 1993 FLOODING


Introduction

The unprecedented flooding in 1993 led the Corps of Engineers to review the management of Coralville Dam for flood control. The following is brief chronology of the steps that have been taken.

Chronology

  • February 1994: In a joint meeting of the Iowa City and Coralville City Councils, the Corps announced plans to reassess the regulation manual. They would "look at many options" and "optimize benefits". Following this, there would be a period of public input and hearings. Final implementation was expected to take many years.

  • May 1994: The US Geological Survey installed automated gages (with financial underwriting from Iowa City, Coralville, and the University of Iowa) to monitor the development of flash floods. The Corps coordinated a standard operating procedure (SOP) for disseminating this information. In addition, the Corps promised to develop (at a future date) a written contingency plan for lake operation in the event of a flash flood.

  • January 1995: An "Initial Appraisal" of lake operations was published which found "evidence of a significantly changed physical, hydrologic, and economic condition upstream and downstream of Coralville Lake." Further study was recommended.

  • August 1995: A "Report on Data Collection 1993 Flood Damage" was completed, updating the stage-damage data upon which a regulation study could be based. (The current regulation plan is based on economic data that had been collected in the 1950's.)

  • August 1997: The "Review of Completed Works Reconnaissance Report" was announced. Surprisingly, the results contradicted all previous milestones. A review of some of the major procedural and technical flaws of this Report was written by Larry Molnar and Charles Newsom. This has been forwarded to the Corps of Engineers and is under consideration.

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    Last updated on September 18, 1997 by CRN