一种新的流域水沙关系模型及其 在年际时间尺度的应用

根据陕西子洲试验站9个流域和山西离石试验站3个流域的观测数据,研究了黄土丘陵沟壑区次暴雨径流和产沙的关系。结果表明:在研究区,当流量超过某一临界值后,含沙量保持稳定,且次洪平均含沙量主要取决于大流量时段,故对于较大的洪水事件,其平均含沙量也趋于稳定,次暴雨和次暴雨过程两个时间尺度的水沙关系表现出很好的相似性。因此可用正比关系式来拟合较大洪水次暴雨径流深和产沙模数之间的关系。由于极端事件对研究区水土流失的重要性,使得该模型有很好的实用性。模型在年际时间尺度上的应用结果表明,对仅在次暴雨期间产流的地区,该模型可以很好地预测年产沙量,而对于常年流水的流域,在丰水年根据汛期径流量该模型也有较好的计算精度。

One new sediment yield model for single storm events and its application at annual time scale

The loess gullied-hilly area of the Loess Plateau in North China is one of the most severely eroded regions in the world with a mean annual soil loss rate exceeding 10000t/ km^2. Based on the observed data here from two stations, the relationship between runoff and sediment yield is examined for single storm events. In the study area, sediment concentration keeps stable when flow discharges are in excess of some critical values, and mean sediment concentration for single flood events mainly depends on the heavy-discharge stage in flood duration. Thus, the mean sediment concentration also keeps stable for heavy flood events. Therefore, one new runoff-sediment relationship model is established for specific watershed. M= Ch, where M is area-specific sediment yield, h is runoff depth. Furthermore, this model has excellent applicability due to the importance of extreme events for soil loss in the study area. The results of the model applied to the annual timescale showed that the model can predict the annual sediment yield very well for the watershed without base flow; and for the watershed where base flow exists, the model can also obtain a good estimation in wet year using the total runoff volume occurred in flood season.