模拟降雨条件下地貌发育与侵蚀产沙的关系

Relationship between erosion sediment yield and geomorphic development under simulated rainfall condition

地貌是影响流域侵蚀产沙的关键因素之一,为了进一步研究地貌发育与侵蚀产沙的关系,该文以小流域概化模型为对象,运用模拟降雨试验方法,以高精度摄影测量和GIS技术为手段对流域地貌发育过程及侵蚀产沙强度变化规律进行了研究。结果表明,产沙速率(Gt)、降雨产沙强度(Gp)和平均输沙强度(M)都随着流域地貌发育过程呈现先增大后减小的变化趋势;在流域地貌发育过程中,存在临界地面裂度(32%左右)和临界相对体积(65%左右),使降雨产沙强度和平均输沙强度的变化趋势由递增变化为递减。这种临界现象对更深入地研究流域地貌发育及其与侵蚀产沙的关系具有重要理论意义,同时说明地面裂度和相对体积可以作为流域发育程度的指标。

Geomorphy is one of the key factors that affect soil erosion in Watershed. For further study on the relationship between geomorphic development and erosion sediment yield, the process of geomorphic development and the variation of sediment yield were studied with generalized small watershed model by simulated rainfall experiment, high-precision photogrammetry and GIS technique. The results showed that the speed of sediment yield （Gt）, sediment yield intensity of rainfall （Gp） and average sediment transport intensity （M） had a tendency of increase at the beginning and then decrease along with the process of geomorphic development. Variation trends of Gp and M turned from increase to decrease at critical ground fracture degree （about 32%） and critical relative watershed volume （about 65%）. This critical phenomenon is very important for studying geomorphic development and sediment yield in depth. It also showed that ground fracture degree and relative watershed volume could be considered as one index of watershed development degree.