鹤鸣观小流域不同土地利用方式的产流产沙特征

Runoff and Sediment Characteristics of Different Land Use in Hemingguan Watershed

针对日益加剧的四川紫色土地区水土流失情况,本文选取四川省南部县鹤鸣观小流域为研究区,分析了流域不同土地利用方式(荒地、灌木林、坡耕地、梯地、林地等)的产流产沙特征及其与降雨的关系以及减水减沙效益。结果表明,该流域不同土地利用方式的次降雨产流产沙特征差异显著,在各类土地利用方式中,荒地的径流系数最大,林地最小,坡耕地的侵蚀模数最大,林地最小;其径流系数与侵蚀模数与次降雨量、降雨强度有一定的相关性;水保措施起到了较好的减水减沙效果,其中林草措施减水减沙效益最好,坡改梯次之,但坡改梯能提高农业产量,经济效益较好。因此,在四川紫色土地区,宜采用生物林草措施与坡改梯相结合的水土保持措施,在坡度较陡的地方退耕还林,在缓坡地带坡改梯。本文为紫色土地区水土流失特征的研究以及水土保持措施的选定提供了一定的依据,为进一步构建小流域分布式侵蚀产沙模型奠定了基础。

Soil and water loss is very serious in Sichuan Province, and it severely affects local agricultural field. The purple soil is a dominant soil in hilly area of Sichuan. The paper took Hemingguan watershed of Nanbu County in Sichuan province as the case and analyzed the characteristics of runoff and sediment in different land use （that is： barren land, shrubbery, sloping cultivated land, terrace land, woodland and so on）, including its relationship with rainfall and effect of reducing water and soil loss. The results show that the difference of runoff and erosion in different land use is significant, runoff coefficient of barren land is maximal and that of woodland is minimal, the erosion modulus of slope cultivation land is maximal and that of woodland is minimal. The runoff coefficient and the erosion modulus are related to the rainfall. The water-and-soil conservation measures have made good effect on reducing water and soil loss, among which the forestry and grass measures have the best effect, followed by the measure of changing slope to terrace, which can increase agricultural yield and therefore has economic benefits. So it is suggested that we should combine the two measures in the purple soil region of Sichuan： in the steep slope we should return land from farming to forestry and in the gentle slope we should take the measure of changing slope to terrace. The study offers an evaluation for the research of characteristics of regional soil and water loss, and for the selection of regional soil and water conservation measures, and establishes a base for the construction of distributed runoff and erosion model.