Regional Variation Features of Sediment Yield Intensity in the Wei River Basin

Based on the distribution of the hydrological station and the different soil erosion type area,132 soil erosion units was divided in the Wei River basin.According to the observation data of sediment,the spatial variation features of sediment yield intensity in the Wei River basin were analyzed.The annual average sediment yield intensity was 4 459.2 t/(km~2·a),sediment yield was 5.2×10~8 t/a,the violence erosive area with erosion modulus ≥5 000 t/(km~2·a) was 5.2×10~4 km~2,the area of it made up 44.3% of the total area of the Wei River basin.The main sediment area were distributed in the loess hilly and gully region above Nanhechuan and Tianshui in Wei River,the area above Qingyang and Yangjiaping in the Jing River,and arid loess hilly and gully region above Liujiahe in the Beiluo River,the sediment yield intensity were 6 000～10 000 t/(km~2·a),and the area of the main sediment area made up 39.1% of the total area of the Wei River basin.Because of the severe soil loss in the upper reaches in the Wei River basin,the silt in river bed in the lower reaches was serious gradually,and lead to potential risk of flood hazards,threaten to the safe of the lower reaches of the Wei River and the Huanghe River.So the soil and water conservation in the Wei River is very important,especially in the main sediment area in the upper reaches.The study of regional fitness of soil and water conservation measures and their collocation should be stressed,the dynamic and real-time observation of soil and water loss should be implemented.