暴雨条件下黄土高原长陡坡耕地细沟侵蚀特征  

Rill erosion of long and steep cropland on the Loess Plateau under heavy rainstorm

作　　者：王志强 杨萌 张岩[2] 张帅 Wang Zhiqiang;Yang Meng;Zhang Yan;Zhang Shuai(School of Geography,Beijing Normal University,Beijing 100875,China;Key Laboratory of State Forestry Administration on Soil and Water Conservation,college of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,China)

机构地区：[1]北京师范大学地理科学学部,北京100875 [2]北京林业大学水土保持学院,水土保持与荒漠化防治国家林业局重点实验室,北京100083

出　　处：《农业工程学报》2020年第12期129-135,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(41671272);国家重点研发计划(2016YFC0501604-05)联合资助

摘　　要：细沟侵蚀是黄土高原坡耕地侵蚀的重要形式,已有的坡耕地细沟研究成果主要集中于裸土细沟侵蚀特征及其发生机制的小区或水槽试验,极端暴雨条件下细沟侵蚀观测很少,对于田间细沟侵蚀的预报仍然缺少实用的方法。该研究旨在基于实地测量数据,分析极端暴雨条件下黄土高原长陡坡耕地细沟侵蚀特征。2017年无定河流域“7.26”暴雨后,在暴雨中心附近选择15个样地进行细沟侵蚀测量,结合Google影像和无人机航拍影像,调查分析不同类型坡耕地细沟侵蚀特征。研究结果表明:1)暴雨条件下坡耕地是坡面细沟侵蚀的主要地类。长陡坡裸露坡耕地侵蚀模数为22478 t/km2,坡长20 m时,约为种植作物的平作坡耕地的1.5倍,且坡长越长,差异越大。等高垄作能够有效减少细沟侵蚀。撂荒坡耕地细沟侵蚀模数仅为裸露坡耕地的12%,草地未发现细沟侵蚀。2)幂函数可以很好地拟合细沟侵蚀模数与坡长的关系,裸露坡耕地坡长指数为0.831。暴雨强度越大,坡长指数也越大。3)上坡来水在坡耕地上造成了严重的细沟侵蚀,与地块上承接的降水相比,上坡来水对细沟侵蚀的影响更大。坡面浅沟汇水明显减小细沟侵蚀强度,浅沟发育程度越高,细沟侵蚀强度就越小。该研究可为估算黄土高原丘陵区不同类型坡耕地的细沟侵蚀提供重要参考。Rill erosion can be defined by concentrated flow in small rivulets.This type of water erosion has posed a great challenge on the sloping cropland on the Loess Plateau in China.Most previous studies were focused on the field or laboratory experiment,while the research on rill erosion under conditions of extreme heavy rain is still lacking,particularly on practical prediction on specific cropland.The purpose of this study is to investigate the characteristics of rill erosion on long and steep slopes under extreme rainstorms based on field survey data.After the heavy rainstorm on the central Loess Plateau on July 26,2017,15 sampling sites were selected based on Google imagery near the rainstorm center with event rainfall of 212 mm and the maximum 60-min rainfall intensity of 49.2 mm/h for rill erosion measurement.In each sampling site,cross-sectional properties were measured at 2-m intervals,and the width and depth of each rill in each section were recorded.Topographic parameters were measured based DSM derived from drone aerial images in 0.20 m resolution.Rill erosion data from a previous study on five plots under storm conditions were used to compare the impact of rainfall intensity on rill erosion along slope length.The results showed that:1)Under rainstorm conditions,the rate of rill erosion on bare sloping cropland was 22487 t/km2,and that on sloping cropland accounted for 68.6%that of the bare land,as the slope length was 20 m.Contouring cultivation can reduce effectively erosion,where the rill erosion was less than 5%that of the bare land,but the downslope rill erosion still occurred.The rate of rill erosion on fallow cropland was only 12%that on bare cropland with the same slope gradient,and no rill erosion was found on grassland.2)The power function,Er=aLb,can fit the relationships between the rill erosion rate and slope length.The index of slope length(b)was 0.831 for the bare land with the slope gradient of 34°.The index of slope length increased as the increase of the rainstorm intensity,indicating that

关 键 词：土壤 侵蚀 暴雨 细沟 坡耕地 坡长 坡度 上坡来水 

分 类 号：S157.1[农业科学—土壤学]