Annual sediment yield in sub-watersheds at upper reaches of Minjiang River: A simulation with SEDD model

Based on GIS, a sediment delivery distributed (SEDD) model was established to simulate the spatial patterns of annual soil water erosion and sediment yield in two sub-watersheds at the upper reaches of Minjiang River. The model was based on the revised universal soil loss equation (RUSLE) for calculating the annual soil water erosion, and coupled with an equation for evaluating the sediment delivery ratio of each cell. The results showed that in most regions of the two sub-watersheds, erosion intensity was below high level. Similar spatial patterns of sediment delivery ratio and sediment yield were observed, i. e., being higher along river, and approached to zero in other regions. Most parts of eroded soil were deposited in the sub-watersheds during their transportation, and less than 5% of it reached the river. Shrub land and forestland were the most important sources of sediment yield, and the sum of their sediment yield occupied 70% of the total.