RUNOFF AND SEDIMENT LOSSES FROM NATURAL AND MAN-MADE EROSION CONTROL MATERIALS

Man-made erosion control materials are increasingly being used st cons truction sites. The performance of these materials in comparison to na tural materials is largely unknown. A rainfall simulation study was de signed in which four man-made materials (wood excelsior, jute fabric, coconut fiber blanket, and coconut strand mat) and two natural materia ls (straw and turfgrass sod) were evaluated. The erosion control mater ials were evaluated on a Sassafras loamy sand (fine loamy, mixed mesic Typic Hapludult) having a 8% slope and on a Sassafras sandy clay loam (fine, silty, mixed mesic Typic Hapludult) having a 14 to 21% slope. Disturbed soil surface areas (0.76 m(2) each) were covered with each m aterial and subjected to a 96 mm hr(-1) simulated rainstorm. Runoff an d sediment loss rates were determined every 5 min for 35 min after rec ording the time required for runoff initiation. Sod was the only mater ial that extended the time required for runoff initiation. Runoff from all materials was less than bare soil for the first 5 min of runoff; however, only straw,jute, and sod reduced runoff over the entire storm event. The total amount of runoff, com pared with bare soil, was decr eased by 61% for sod, 25% for straw, and 16% for jute. Erosion control materials reduced bare soil erosion by 80 to 99%. Of the man-made ero sion control materials, only jute reduced runoff and sediment losses a t both locations. Therefore, of the materials tested, only sod, straw, and jute would be expected to effectively reduce both runoff and sedi ment losses.