大别山南麓裸地小区径流泥沙过程对降雨特征的响应

作为水土流失重点预防保护区,大别山南麓裸地坡面水土流失严重,为探究该区典型裸地坡面径流泥沙对降雨的响应,利用自动化径流泥沙监测设备对裸地径流小区的降雨—径流-泥沙过程进行监测。以2020年全年侵蚀性降雨数据为基础,依据降雨峰值时序划分雨型,分析了4种雨型的累计产流产沙特征和次降雨的径流泥沙特征,并建立了累计产流产沙的最优函数模型。结果表明:(1)大别山南麓降雨事件的I₃₀是影响降雨事件的泥沙量和径流系数的重要因素;前期集中型和中期集中型降雨事件的泥沙量与前48 h内的降雨量呈显著正相关。(2)不同雨型下产流产沙过程有显著差异,但径流泥沙指标的差异不显著。不同雨型下累计产流产沙的最优模型为Logistic模型。(3)不同雨型下,雨强、产流率和产沙率的变化趋势和峰值出现规律存在一致性,也存在产沙产流过程滞后于雨强变化过程的现象,产沙滞后多出现在前期集中型降雨,产流滞后多出现在中期集中型和后期集中型降雨。研究结果揭示了降雨-产流-产沙相互关系,对该区域坡面水土流失防治具有一定的科学指导意义。

Response of Runoff and Sediment Process to Rainfall Characteristics in Bare Land Plots in Southern Foot of Dabie Mountain

As a key soil erosion prevention reserve, the bare slope of the southern foothills of Dabie Mountain has serious soil erosion. In order to explore the response of runoff and sediment to rainfall on typical bare land slopes, the rainfall-runoff-sediment process of bare land runoff plots was monitored by automatic runoff and sediment monitoring equipment. Based on the annual erosive rainfall data in 2020, the rainfall patterns were divided according to the rainfall peak time series. The characteristics of cumulative runoff and sediment yield of the four rainfall patterns and the runoff and sediment characteristics of individual rainfall were analyzed, and the optimal function model was established. The results showed that: (1) The maximum 30 min rainfall intensity was an important factor affecting the sediment volume and runoff coefficient of rainfall events in the southern foot of Dabie Mountains. There was a positive correlation between the rainfall and sediment load in the first 48 hours of initial and middle concentrated rainfall events. (2) There were significant differences in the process of runoff and sediment yield under different rainfall patterns, but the difference of runoff and sediment indexes was not significant. The optimal model of cumulative runoff and sediment yield under different rainfall patterns was Logistic model. (3) Under different rainfall patterns, the variation trend and peak value occurrence rule of rainfall intensity, runoff rate and sediment yield rate were consistent, and the process of sediment yield lagged behind the process of rainfall intensity. The lag of sediment yield mostly occurred in the early stage of concentrated rainfall, and the lag of runoff mostly occurred in the middle and late stage of concentrated rainfall. The results can reveal the relationship between rainfall-runoff-sediment yield, which has certain scientific guiding significance for the prevention and control of soil and water loss on the slope in this area.