U.S. Department of Agriculture: Forest Service -- National Agroforestry Center


Date of this Version

July 2005


Written for presentation at the 2005 ASAE Annual International Meeting. Sponsored by ASAE. Tampa Convention Center. Tampa, Florida. 17 - 20 July 2005.


Vegetated filters (buffers) are used to intercept overland runoff and reduce sediment and other contaminant loads to streams (Dosskey, 2001). Filters function by reducing runoff velocity and volume, thus enhancing sedimentation and infiltration. lnfiltration is the main mechanism for soluble contaminant removal, but it also plays a role in suspended particle removal. By decreasing the discharge and velocity of overland flow, infiltration causes a decrease in sediment transport capacity, and thus sedimentation is enhanced.

Although the impact of infiltration on soluble and suspended contaminant removal has not been directly documented, many researchers suggest infiltration plays a significant role (Table 1). In developing a design algorithm for vegetative filters, Edwards et al. (1996) suggested that infiltration is the only significant mechanism for removal of soluble nutrients.