Characteristics of Erosion Control Measures and Their Impact on Erosion

Abstract

This project endeavored to expand experimental data on erosion control blankets and develop greater understanding of how blankets and erosion principles interact. Blankets that are effective in reducing raindrop impact may become ineffective in controlling soil detachment and runoff (rill erosion) on longer slopes. This field study of erosion control products under artificial rainfall conditions was conducted at the Highway 10 overpass in Coon Rapids, Minnesota. Examining long slope lengths (60 feet and 100 feet), bare soil erosion was compared to erosion under straw blankets, wood fiber blankets, straw mulch, and sprayed emulsion. Measurements of runoff, erosion, and biomass (vegetative growth) were made in spring and fall under wet and dry conditions. Sediment loads for bare soil were 8 times larger than other treatments. Sediment loads were substantially smaller for the fall runs than the spring runs, largely due to the substantially increased vegetative cover (biomass). Shear stress partitioning for erosion control blankets was evaluated using a laboratory flume and hot-film anemometry. Erosion control blankets partition shear stress into form shear (the portion that acts on the blanket) and particle shear (the portion that acts on the soil particles). Blanket type, flow conditions, and fastener impacts were considered. Shear partitioning was found to be an important process in design and erosion modeling. Attempts were made to correlate sediment load and vegetative density data gathered by Texas Department of Transportation (TxDOT) with manufacturer's information on blanket characteristics. However, the data from manufacturers was insufficient to determine patterns or predict performance. Keywords-erosion control products, vegetation establishment, soil erosion, slope hydrology