HYDRAULIC EQUATIONS

have been widely used to describe flow characteristics. Each of these relations contains a roughness coefficient. Under uniform flow conditions, the Darcy-Weisbach roughness coefficient, f, is given as (Chow, 1959): regarding rill density is limited. In addition to flow rate, identification of other rill hydraulic variables such as rill width, hydraulic roughness coefficient, and flow velocity may also be important. Rill flow serves as the mechanism by which sediment is transported from upland areas. If the hydraulic characteristics of rill flow can be more accurately defined, upland erosion processes can be better understood and more accurately modeled. A laboratory study of rill hydraulics was described by Foster et al. (1984 a, b). A full-scale fiberglass replica of