大别山区不同降雨和植被条件下梯地产流产沙特征

大别山区是国家水土保持重点建设工程的主要区域之一,为探究不同时间尺度下不同降雨等级和植被类型对产流产沙影响,基于霍山县水土保持试验站2011—2018年的试验小区自然降雨及产流产沙量观测数据进行了定量分析。结果表明:(1)在次降雨事件的时间序列分析中,2011—2018年次降雨存在雨量更大、雨势更急的趋势,茶叶相对于黄豆等其他植被,具有显著的保沙能力,且其减沙效益高于减流效益,8年的黄豆种植使得土壤侵蚀愈发严重。(2)在99%的置信水平下,黄豆的产沙风险是茶叶的21.29倍。(3)随着降雨等级提升,产沙风险也逐步提升,其中暴雨和大暴雨产沙风险较其他降雨等级显著提升。(4)茶叶出现产沙与瞬时雨强相关,雨强对产沙的重要性高于雨量,黄豆多由产流而导致产沙,雨量对产沙的重要性高于雨强,各因子对茶叶的评价平均精度高于黄豆。(5)黄豆处于三叶期—开花期和结荚期—成熟期时具有较好的保水保沙效益,而三叶期—开花期产流产沙峰值主要由于高水平的雨量雨强导致。研究结果较好地显示了茶叶和黄豆在不同降雨及生长状态下的产流产沙特征及影响因素,可为大别山地区以减少水土流失为目的的植被种植与管护提供科学依据。

Study on Runoff and Sediment Characteristics of Terrace Land Under Different Rainfall and Vegetation Conditions in Dabie Mountain

Dabie Mountain area is one of regions of the national soil and water conservation key construction projects.In order to explore the effects of different rainfall grades and vegetation types on runoff and sediment yield under different time scales,a quantitative analysis was carried out based on the observed data of natural rainfall,runoff and sediment yield from 2011 to 2018 in Huoshan Soil and Water Conservation Experimental Station.The results are as follows.(1)In the time series analysis of the rainfall events,the rainfall in 2011—2018 had a trend of heavier rainfall and more rapid rainfall.Compared with other vegetation such as soybeans,tea trees had significant sediment retention capabilities.Moreover,the benefits of sediment reduction were higher than the benefits of runoff reduction.Eight years of soybean planting had made soil erosion worse.(2)At the 99%confidence level,the sediment production risk of soybeans was 21.29 times that of tea plants.(3)As the rainfall level increased,the risk of sediment production gradually increased.Among them,the risk of torrential rain and heavy downpour has increased significantly compared with other rainfall levels.(4)The occurrence of sediment production in tea plants was related to the instantaneous rainfall intensity,and the rain intensity was more important for sediment generation than the amount of rainfall.Sediment generation was mostly caused by runoff in soybean fileds,and the amount of rainfall was more important for sediment than rainfall intensity.The average accuracy of tea plant evaluation was higher than that of soybean.(5)Soybeans had better water and sediment retention benefits when they were in the phases of three-leaf period-flowering period and pod-bearing period-maturity period,while the peak of runoff and sediment yield during the three-leaf period-flowering period was mainly caused by heavy rainfall.These results show the characteristics and influencing factors of runoff and sediment production of tea and soybeans under different rainfall levels and growth conditions,and can provide a scientific basis for vegetation planting and protection in Ta-pieh mountain area for the purpose of reducing soil and water losses.