黄土塬区马莲河流域侵蚀产沙变化特性

Erosion and sediment yield in the Malian River Basin of the Loess Tableland

塬是黄土高原地区特有的地貌类型,长期以来的土壤侵蚀导致黄土塬严重破碎,塬区生产及生态环境问题日益受到关注。董志塬是现存面积最大的完整塬,马莲河位于董志塬东侧,坝库工程较少,河道输沙基本为自然过程。采用马莲河流域6个水文站1954-2017年实测输沙资料和统计学方法,系统研究了流域及塬区土壤侵蚀产沙变化的格局。结果表明:马莲河流域年输沙量与输沙模数随时间变化呈下降趋势,流域多年平均输沙量为1.15亿t,并以年125.38万t的速率下降。流域输沙量具有明显的阶段性,经历了丰沙阶段(1954-1977年、1988-2003年)与枯沙阶段(1978-1987年、2004-2017年)。流域上游输沙量大于下游输沙量,产沙中心位于上游,并且由北向南递减。

The loess tableland is a unique landform type in the Loess Plateau area. The long-term soil erosion has led to a serious fragmentation to the loess tableland. The agricultural production and ecological environment problems in the reclamation area are influenced seriously. Dongzhi Tableland is the largest and most complete plateau in the existing area. Malian River is located in the eastern part of Dongzhi tableland,where the water quality is not suitable for drinking. The sediment transport in this area is close to natural condition owing to lack of reservoirs. The pattern of soil erosion and sediment yield in the basin and tableland were studied by the data and statistical methods of sediment transport observed at six hydrological stations in the basin in 1954-2017. The results show that the annual sediment transport in the Malian River Basin decreased with time. The average annual sediment transport in the basin was 115 million tons and decreased at a rate of 12 538 million tons. The sediment transport in the upstream of the basin is greater than that in the downstream,and the sediment production center is located in the upstream,and decreases from north to south.