【摘要】 对陕南低山丘陵区水土流失状况的调查和径流观测表明，低山丘陵区是陕西省长江流域水上流失最为严重的地带，坡耕地又是水土流失的主要来源，２５°以上的坡耕地年土壤侵蚀量可达３万吨／ｋｍ２以上，土壤侵蚀的绝对临界坡度为５．５５７°，许可临界坡度为１８°，速增点为２２°，速增区间为１９°～２４．７５°；森林植被的覆盖是防止水土流失的根本措施。更多还原

【Abstract】 The investigation of soil and water erosion on the lower mountain and hills region and the experiment result from the runoff plots show that the lower mountain and hills region is the most serious zone with siol and water losses, the farm land on the steep slope is a major source for soil and water loosing ,the soil erosion modulus on steeping farm land with 25° reaches 30000t/km2. Year ; the absolute critical slope for soil erosion is 5. 557°,allowancing critical slope is 18°, accelerating point is at 22°, the acceleraing period are from 19°to 24. 75°,the forest covering is a fundamental measure to control the soil and water erosion.更多还原