泥沙源区沟道输沙能力的计算方法

Sediment transport capacity of gullies in small watersheds

小流域沟道是泥沙进入江河的初级通道 ,在洪水流量较大时 ,沟道挟沙力强 ,其输沙量往往接近断面以上流域侵蚀量 ,进入江河的沙量取决于流域内的补给沙量 ,但在洪水流量较小时 ,沟道水流挟沙力下降 ,其输沙量小于断面以上流域侵蚀量 ,进入江河的沙量取决于各级沟道的挟沙能力。黄土地区小流域沟道纵坡陡 ,固体物质补给又十分丰富 ,虽然沟道尺度不大 ,但水流含沙量却很高 ,已有各种基于低含沙水流的挟沙公式不能表达沟道中高含沙水流的输沙特性。作者通过分析及试验研究 ,求得在输沙平衡条件下水流泥沙因子间的关系 ,提出小流域沟道挟沙力公式 ,经初步验证结果满意 ,这为估算分析不同条件下流域输沙量提供依据 ,也对水土保持规划有一定的指导意义。

Gullies of small watersheds are the primary channels of sediment entering the river. When the flood discharge is high,the sediment transport capacity of gullies is high and the amount of sediment going into the river is close to the actual sediment yield from catchment areas above the control section.However, in cases of lower flood flow, the amount of sediment sent into the river will be limited by the transport capacity of the gullies.In the hilly regions of the Loess Plateau of China,the sediment content in water flow is very high due to the steep slope and abundant supply of eroded material, and the formulas of sediment transport capacity usually used for lower sediment content will not be applicable.In this paper a new formula of sediment transport for high concentration flow in gullies is developed based on experimental data.It is then verified by observed data.The formula may be used to estimate the sediment transport of small catchments and in the planning of soil conservation measures in small watersheds.