STREAMBANK EROSION
The erosion of fine-grained streambank soils (those containing primarily small soil particles, such as silts and clays) has profound and widespread impacts on society. The physical degradation of channels decreases the stability of earthen dams, levees, and stream-side infrastructure, including sewer and water lines, utilities, buildings, and bridges. Not only does this eroded sediment threaten infrastructure, but once eroded, this fine sediment becomes a water pollutant. Excess suspended sediments reduces the diversity and abundance of aquatic organisms, increases the need for dredging, reduces hydropower and water supply reservoir capacity, increases drinking water treatment costs, and serves as a carrier for contaminants such as phosphorus, bacteria, heavy metals, pharmaceuticals and pesticides. The costs of water pollution due to sediment in North America alone range from $20 billion to $50 billion annually. In some watersheds, streambank erosion contributes as much as 92% of the fine sediment in streams.
Reducing streambank retreat, and the resulting impacts, requires an improved understanding of the fundamental processes causing the loss of fine-grained soils. However, in many respects, this field is in its infancy; progress in this area is constrained by the lack of a consistent testing methodology and efficient testing devices. My research group has demonstrated that the time between sample preparation and testing, as well as the temperature of the eroding fluid significantly affect erosion test results. We are currently working to develop an erosion testing methodology that provides consistent results, a test device that allows rapid, controlled testing in standard laboratories, and well defined, standardized soils to allow us to test a greater range of water temperatures and pH, and soil types, with the long-term goal of developing a mathematical model to predict the onset and rate of streambank erosion. Engineers designing stream restoration projects and stream-side structures, including bridges, levees, and earthen dams, will be able to assess the impacts of land use and climate change on their designs. These predictions will result in more robust infrastructure projects and improvements in water quality.
Reducing streambank retreat, and the resulting impacts, requires an improved understanding of the fundamental processes causing the loss of fine-grained soils. However, in many respects, this field is in its infancy; progress in this area is constrained by the lack of a consistent testing methodology and efficient testing devices. My research group has demonstrated that the time between sample preparation and testing, as well as the temperature of the eroding fluid significantly affect erosion test results. We are currently working to develop an erosion testing methodology that provides consistent results, a test device that allows rapid, controlled testing in standard laboratories, and well defined, standardized soils to allow us to test a greater range of water temperatures and pH, and soil types, with the long-term goal of developing a mathematical model to predict the onset and rate of streambank erosion. Engineers designing stream restoration projects and stream-side structures, including bridges, levees, and earthen dams, will be able to assess the impacts of land use and climate change on their designs. These predictions will result in more robust infrastructure projects and improvements in water quality.