陕南河流泥沙输移比问题

通过分析陕南河流泥沙的输移比现状、输移比的时空变化及发展趋势，指出在特定的自然地理条件下，泥沙中推移质比例较大，致使该区泥沙输移比远小于１，这是陕南河流泥沙运移的重要特征；输移比在空间上有明显差异并且沿程逐渐增大。从时间上看，自５０年代以来，输移比有不断减小的趋势，今后一段时间，随着区内河流径流量的减少和人为侵蚀作用的加剧，泥沙输移比仍会减小。

THE PROBLEM ABOUT THE RIVER SILT DELIVERY RATIO IN SOUTH SHAANXI

This paper analyses the present situation of river silt delivery ratio, the delivery ratio change in time and space, and the development trend in South Shaanxi, indicates that under the spesific physical geography conditions, the tractional load ratio in the silt is rather great and it made the delivery ratio of this district less than 1. This is a very important character of river silt migration in South Shaanxi; the delivery ratio has an obvious difference in space; generally, it gets bigger along the river flow; considering the time, it has had the trend of decrease since the fifties, and in the coming days, with the decrease of river silt runoff volume and the manmade erosion worsening in this district, the silt delivery ratio will decrease further.