Computer Simulation Prognosis for the Degradation of the Missouri River between Gavins Point Dam and Iowa's Southern Border, August 1983

(1983) Computer Simulation Prognosis for the Degradation of the Missouri River between Gavins Point Dam and Iowa's Southern Border, August 1983. University of Iowa

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Abstract

The bed of the Missouri River between Gavi ns Point Dam and Omaha has undergone extensive bed degradation since 1950. This scouring has had severe consequences, including potential undermining of structures, loss of wildlife habitat, and lowering of the water table with associated increased pumping costs and dropping of water levels in oxbow lakes used for recreation. River bed degradation is a comp 1 ex process which, before the advent of the computer and associated computational-hydraulics techniques, was not subject to rational, deterministic analysis. However, now that such techniques are available, it has become possible to simulate long term river bed evolution in response to changed river geometry, hydrologic regime, and sediment supply. The IALLUVIAL computer program, developed in 1981-82 at the Iowa Institute of Hydraulic Research, has been applied in previous studies to simulation of the past twenty years of Missouri River bed degradation. The success of !ALLUVIAL in reproducing past bed degradation laid the groundwork for the present study, whose goals included modification of IALLUVIAL to treat more realistic river conditions, including tributaries, bank erosion, and vertical nonhomogeneity of bed sediments, and then use of the improved version of !ALLUVIAL to simulate bed degradation over the next twenty years, 1980-2000. These prognosis simulations, performed for various hypothetical scenarios of river management, showed the sensitivity of Missouri River bed degradation to geometric, hydrologic, and sediment variables, and furnished indications of the expected pattern of future degradation.