Bank material contributes as much as 80% of the total sediment eroded from incised channels in the loess area of the midwestern United States. This erosion occurs as bank failures. The eroded farmland is delivered to streams and potentially lakes and reservoirs, and severely impacts water quality, fish and wildlife, and ecological habitat. Attempts to predict channel widening, meander migration and land loss are limited by a lack of understanding of the way in which streamflow interacts with bank-toe material.
The research is aimed at addressing the interaction of bed and bank processes and to investigate incipient motion criteria for failed bank material. The interaction of these processes is studied in the context of their controls on long-term rates of bank retreat, channel migration, and the development of equilibrium channel morphology.
Description of Work:
Actively migrating incised meander are monitored for changes in morphology and sediment characteristics following storm flows. Integration of hydraulic, sedimentologic, and geotechnical variables and processes are studied to address questions on bank-failure mechanics, deposition of failed bank material, and re-entrainment of the failed material. These data are supported by historical surveys, aerial photographs, and botanical evidence.
Results will be used to improve predictive ability of (1) bank-erosion processes and rates of land loss associated with bank-toe erosion, (2) yields of sediment emanating from channel banks, and (3) mitigation strategies to reduce land loss associated with bank erosion.