黄河中游降雨特性对泥沙粒径的影响

以黄河中游36个有泥沙粒径资料的水文测站流域为样本，在不同自然地理类型流域划分的基础上，建立了流域泥沙粒径特片与降雨特性的关系。结果表明，在不同类型流域，流域泥沙的粗细与降雨季节性变率和年际变率之间存在着相当好的线性正相关关系；而与年降雨量和降雨不均匀系数之间呈明显的非线性关系。流域地面物质、植被和地貌发育程序等下垫面环境因素对泥沙粒径特性与降雨特性之间关系起着十分重要的控制作用。不同类型流域曲线的斜率各不相同，在图中所处的位置也不相同。

Relationships Between Grain Size of Suspended Sediment and Rainfall Characteristics in the Middle Reaches of the Yellow River Basin

Thirty-six river basins, where the data of measured grain size of sediment are available, were chosen for an analysis on relationships between grain size of sediment and rainfall features in the middle reaches of the Yellow River. These basins fall into 5 types of different physio-geographical environments. Annual average rainfall, unevenness, seasonality and yearly variation of rainfall were taken as the indices of rainfall to relate to grain size of sediment. It was shown that good linear positive multi-relationships exist between grain size of sediment and seasonal and annual variation of rainfall when taking the different types of basin as perameters, but simple non-linear relationships between grain size of sediment and annual average rainfall and unevenness of rainfall. Vegetation, surface material and landform exert an important control on the relationships between grain size of sediment and rainfall features. Different slope and positions of curves were observed in the relationships between grain size of sediment and seasonal and annual variation of rainfall for different types of river basins. The slope of curve decreases and the position moves down subsequently from the basins of windy sand, sandy loess and heavily weathered siltstone and mudstone to those of loess and clayey loess. The different positions were also observed in the relationships between grain size of sediment and annual average rainfall and unevenness of rainfall for different types of river basins. From the upper to the lower of the curve the type of river basin changes from the basins covered by windy sand, sandy loess or heavily weathered siltstone and mudstone to those of loess and clayey loess subsequently.