Because of its simplicity, the sediment delivery ratio (SDR), based on the ratio of the sediment yield (Y) and the gross erosion (E) in the basin, is widely used to estimate sediment production in watersheds. Since Y and E are complexly linked, several SDR equations were developed. Financial compensation programs resulting from sedimentation abatement, such as the Water Provider Program, often require the estimation of reduction of the downstream sediment yield as a function of erosion reduction upstream. This study was conducted at the Forestry Department of the Universidade de Brasília-UnB, and in the Pipiripau river basin, in November 2007. The SDR of the Pipiripau river basin (DF) was calculated based on eight equations used in the literature, to estimate the reduction in Y due to a reduction of 50 % of E in the basin, as well as to evaluate eventual limitations of their application. The SDR values varied from 0.12 to 0.52, with a mean of 0.24 and a standard deviation of 0.14. Two of the eight equations were highly sensitive to the variables, indicating a high potential for error propagation. With a 50 % reduction in the gross upstream erosion (117.500 t yr-1), the corresponding reduction in sediment yield using the SDR of the eight equations varied from 14,000 to 61,000 t yr-1. This significant variation in sediment yield results in uncertainties in the estimation of the environmental services for sedimentation abatement, in erosion control programs.
erosion potential; watershed management; SDR; environmental services
