DISTRIBUTED EVALUATION OF THE CONTRIBUTION OF SOIL-EROSION TO THE SEDIMENT YIELD FROM A WATERSHED

The correct determination of the sediment yield from a basin is of par amount importance in several hydraulic and environmental applications, such as the evaluation of the storage reduction of artificial reservo irs. However, due to the highly episodic nature of sediment supply and transport in many environments and to the extreme complexity of the p rocesses involved, the evaluation of the sediment load in a river is s till highly uncertain. When the time scale of interest is sufficiently long, and when the primary sediment source comes from distributed ero sion in the watershed, the problem can be tackled in an indirect fashi on, by computing the contribution to the annual suspended sediment yie ld from soil erosion, In order to accomplish this task, we propose a d istributed application of the widely used USLE formula. The formula is automatically applied along drainage networks derived from a digital elevation model and properly modified to take into account the presenc e of deposition zones in the watershed. (C) 1997 John Wiley & Sons, Lt d.