Bank Stability Analysis for the Upper Missouri River

摘要

Changes in the operation of Fort Peck and Garrison dams on the Upper MissouriRiver in Montana and North Dakota have been proposed as a means to enhance fisheries and wildlife interests, while continuing to fulfill essential flood-water storage and hydropower functions. To investigate the possible impacts of the proposed regulated flow regime on fluvial bank erosion and bank stability with respect to mass failure, a field and modeling study was undertaken. Modeling studies were conducted using data at 18 study sites selected to represent the range of conditions encountered in the field. Contemporary (September 1995) conditions of bank stability with respect to mass failure, identification of problem reaches, and identification of dominant erosion processes were characterized using stream reconnaissance. The short-term (<5 years) impact on bank stability with respect to mass failure is analyzed by simulating changes in key bank hydrological parameters. Short-term impacts on bank stability with respect to mass failure are negligible. The long-term (up to 50 years) impacts on near-bank bed scour and fluvial bank erosion, and bank stability with respect to mass failure are analyzed by extrapolating historical trends of channel adjustment into the future under the existing flow regime.