不同放牧强度荒漠草原产流产沙过程模拟

Simulation of Runoff and Sediment Yield in Desert Steppe with Different Grazing Intensities

为揭示长期放牧的荒漠草原坡面产流产沙特征,以放牧15年的4种放牧强度的内蒙古荒漠草场土壤为研究对象,在室内人工模拟降雨条件下,探究放牧强度及雨强对草原坡面产流产沙耦合过程的影响。结果表明:(1)不同雨强下,不同放牧草场间的初始产流时间均随放牧强度的增大而提前;产流速率呈现先增长后稳定的状态,4种放牧强度草场的产流速率规律及其波动幅度均为重度放牧(HG)>中度放牧(MG)>对照(CK)>轻度放牧(LG),且雨强对产流速率的影响大于放牧强度。荒漠草原累计径流量与降雨历时呈线性相关,且拟合度较高;(2)荒漠草原产沙速率变化呈现多谷多峰的特点,雨强和放牧强度及二者的交互效应对产沙速率有极显著影响。不同雨强下,4种放牧强度草场的产沙速率规律及其波动幅度均为HG>MG>CK>LG。泥沙流失总量与降雨历时之间呈二次曲线关系。

To reveal the characteristics of runoff and sediment yield on the slope of the desert steppe for long-term grazing,taking the grazing desert steppes(Inner Mongolia area)with four different intensities as the research object,and all steppe were grazing for 15 years.Indoor artificial simulated rainfall was conducted to explore the effects of grazing intensity and rainfall intensity on coupling process of runoff and sediment production on the steppe slope.The results were as follows:(1)Under the different rainfall intensities,the initial runoff time of different grazing steppe advanced with the increasing of grazing intensity,and runoff yield rates increased first and then showed a state of stability.The runoff yield rate and its fluctuating range both followed the order of heavy grazing(HG)>moderate grazing(MG)>control(CK)>light grazing(LG).The influence of rainfall intensity on runoff yield rate was greater than that of grazing intensity.The cumulative runoff yield of desert steppe was linearly related to rainfall duration and the fitting degree was higher.(2)The change of sediment production rate in desert steppe was characterized by multi-valley and multi-peak.Rainfall intensity,grazing intensity and their interaction had a significant effect on sediment production rate.Under different rainfall intensities,the sediment production rate and its fluctuating range followed the order of HG>MG>CK>LG.The relationship between total amount of sediment loss and rainfall duration fit a quadratic curve.