Bed degradation of the lower Missouri River
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The phenomenon of bed degradation can be due to a multiplicity of causes, but ultimately reflects a change in either the sediment input or sediment transport capacity of a system. Causes for the accelerated rate of degradation of the lower Missouri River Bed, particularly in Kansas City are explored as well as potential countermeasures to arrest the incision. Main-stem rivers and their tributaries constitute a complex, interrelated system and consequently the Platte and Kansas Rivers are briefly discussed as well. Although the lower Missouri River Valley has been inhabited for over two hundred years, significant changes on the scale required to disrupt sediment transport patterns has only occurred within the last century or so. Major channelization efforts orchestrated by the federal government began around the turn of the nineteenth century. These operations coupled with a series of main-stem dams built between the 1930s and 1960s served to provide a navigation channel for commercial barge traffic as well as provide flood protection. It appears that clear water releases from upstream reservoirs and effects of the Platte River contribute little to nothing as far as degradation processes at Kansas City are concerned. Channelization works probably play a minor role, as well as land-use changes, such as deforestation and urbanization. Significant causes to the recent increase in degradation rate are major flood events and commercial dredging. The river often degrades several feet during a single flood event and although some recovery occurs, the river's bed never reaches its previous elevation. Commercial dredging has significantly increased in the Missouri River in the same time frame that degradation has accelerated, occurring in the same areas as well. A few European rivers that also experience bed degradation were evaluated along with countermeasures applied to them. Unfortunately, the use of the European rivers lent itself to methods to arrest degradation that are unreasonable for use on the Missouri River. In light of the probable causes for degradation, the most effective countermeasure is likely a change in dredging regulations. Further study is required, though, to more satisfactorily determine the cause(s) of degradation as well as possible countermeasures.
Table of Contents
Introduction -- Development and causes of degradation -- Impacts of degradation -- European rivers case studies -- Degradation countermeasures -- Conclusions and recommendations