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Title: Phase 1 : Investigation of neotectonic activity within the Lower Mississippi Valley Division
Authors: Water Engineering and Technology, Inc.
United States. Army. Corps of Engineers. Vicksburg District.
United States. Army. Corps of Engineers. Lower Mississippi Valley Division.
Schumm, Stanley Alfred, 1927-
Watson, Chester C.
Burnett, A. W.
Keywords: Earth movements
Mississippi River
Geophysical survey
Publisher: U.S. Army Engineer Waterways Experiment Station.
Engineer Research and Development Center (U.S.)
Series/Report no.: Report (Potamology Program--P-1 (U.S.)) ; 2.
Description: Potamology Report
Abstract: This report is the first in a series of a three phase study of the effects of neotectonics upon the Mississippi River and tributaries. The objective of this preliminary study was to evaluate the hypothesis that gradual and presently continuing movements of the earth surface are affecting Mississippi River and tributary channel characteristics to such an extent that these effects should be included as design considerations for navigation and flood control projects. A review of literature indicates that several major rivers are affected by tectonics. However, since alluvial channels are sensitive indicators of change in hydrology and sediment load and type as well as tectonics, the degree to which rivers are controlled by tectonics alone has not previously been thoroughly investigated. The examples discussed in the literature of tectonic control of river behavior deal primarily with rather dramatic movements, earthquakes, and with the influence of rocks of different resistance emplaced along the channel. The literature has been less specific about the effects of gradual and continuing crustal movements in a large alluvial river such as the Mississippi. This report provides evidence to indicate that the effects of crustal movement in a river system can be categorized as follows: (1.) Change in watershed drainage pattern (2.) Channel aggradation or degradation (3.) Change in channel pattern or sinuosity (4.) Channel diversion or avulsion (5.) Flooding due to subsidence. This preliminary report demonstrates that at least three major geologic uplift features continue to be active in the Mississippi Valley and that influence of these features may impact present navigation and flood control features. Geologic and precise level surveys indicate that crustal uplift of about 3 mm per year can be expected at some locations within the Mississippi Valley. The average low water reference plane gradient of the Mississippi River is only about 90 mm per mile, or about half the width of this page per mile. It is easy to understand the significance of a gradual 3-mm per year movement that is accumulated over a project life of 50 years. Further, it can be seen that the same accumulation of uplift could be a significant cause for perculiarities of channel behavior which develop over a period of years in a channel reach that otherwise has been free of problems. This is the report for the preliminary phase of this study. Further phases of the study are to be directed to additional definition of the effects of crustal movement, to a specific investigation of particular locations, and to development of design criteria encompassing these long-term effects in planning for navigation and flood control projects. NOTE: This file is large. Allow your browser several minutes to download the file.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Potamology Investigations Report

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