Controlling Bank Erosion
Soil erosion and water runoff from excavated banks can be a major safety problem and engineering challenge, particularly on new home sites or new bank plantings. Many materials are available to help control erosion until the permanent plantings have rooted sufficiently to knit the soil in place. But how do they compare?
In a study from the University of Maryland researchers compared six materials for their ability to reduce erosion and runoff: sod, oat straw, wood excelsior, jute fabric, coconut-fiber blanket, and coconut-strand mats. The slopes were steep but mowable (8 and 21 percent grades). Researchers found all the materials significantly reduced soil loss compared to bare soil, and there were no major differences in erosion control among the materials.
More interesting were differences in ability to reduce runoff. Surprisingly, the sod and oat straw outperformed all the other materials. Total water runoff was reduced 61 percent by sod and 25 percent by straw spread at less than 1 inch thick. Of the other materials, only jute significantly reduced water runoff, by 16 percent. This was largely due to the fact that natural materials cover more soil surface area than the manufactured ones. Straw has the added benefit of promoting the rapid establishment of vegetation.