大通江、平洛河水保措施减水减沙分析

嘉陵江流域水土流失严重，“长治”工程首批治理的四大片区中，嘉陵江上游的陕南陇南地区和中下游土石山区两大片区名列其中。自20世纪80年代末开始实施水土保持治理以来，对控制流域内水土流失现象起到了较为明显的积极作用。选择了分别位于两大片区的大通江和平洛河两条典型河流，以实测水沙资料为依据，采用水文学方法，着重分析研究两个典型流域水保措施实施以来的水沙变化。

Analysis of the Soil and Water Conservation Measures Reducing Runoff and Sediment in the Datong and Pingluo River Basins

The Datong River is the fourth order tributary of the Jialing River.The river basin lies in humid semitropical monsoon climate region with a catchment area of 160 000 km².The Pingluo River is one of the largest tributaries of the Xihanshui River with a catchment area of 741 km².The climate condition of the Pingluo River basin is different from that of the Datong River.It has arid climaate and less precipitaion.Both river basins are typical catchments of the Jialing River with different geological,physiographic and climatic conditions.They are the main sediment sources of the Jialing River basin.After implementation of the soil and water conservation measures in the upper Yangtze River,the total area that has brought under control reached 25.8 percent of the total soil and water loss area before 1996.The soil and water losses have been greatly reduced.The change in runoff,sediment,and their relationship are analyzed on the basis of measured hydrologic data in the two typical catchments of the Jialing River.