极端降雨下黄土高原草被沟坡浅层滑坡特征及其对产流产沙的影响  

Characteristics of shallow landslides under extreme rainfall and their effects on runoff and sediment on the Loess Plateau

作　　者：许阳光 郭文召 王文龙 罗少辉[3] 陈卓鑫 娄义宝 费建坪 XU Yangguang;GUO Wenzhao;WANG Wenlong;LUO Shaohui;CHEN Zhuoxin;LOU Yibao;FEI Jianping(State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau,Institute of Soil and Water Conservation,Northwest Agriculture and Forestry University,Yangling 712100,China;Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,Yangling 712100,China;Qinghai Meteorological Disaster Prevention Technology Center,Xining 810000,China)

机构地区：[1]西北农林科技大学水土保持研究所,黄土高原土壤侵蚀与旱地农业国家重点实验室,杨凌712100 [2]中国科学院水利部水土保持研究所,杨凌712100 [3]青海省气象灾害防御技术中心,西宁810000

出　　处：《生态学报》2022年第19期7898-7909,共12页Acta Ecologica Sinica

基　　金：国家自然科学基金项目(41907057,42077079);陕西省自然科学基础研究计划项目(2021JQ-165);中国博士后科学基金面上项目(2020M683591)。

摘　　要：植被恢复作为黄土高原防治水土流失的重要措施,但极端降雨诱发的浅层滑坡在植被恢复的沟坡上频繁发生,影响流域的产流产沙过程。基于野外原位模拟降雨试验,在60 mm/h降雨强度下,研究草被沟坡浅层滑坡发生特征及其发生前后的产流产沙差异。结果表明:(1)极端降雨所诱发的草被沟坡上的浅层滑坡深度为14—36 cm,与自然强降雨所导致的浅层滑坡深度相贴合,均是低于50 cm。(2)植被根系与土壤容重、孔隙度等土壤性质显著相关(P<0.05),致使滑坡面上、下层土壤物理性质差异显著(P<0.05)。由于土壤性质的差异,在极端降雨下滑坡面上层土壤水分更快达到饱和(饱和度>90%),导致浅层滑坡的发生。(3)草被坡面浅层滑坡后的径流与产沙均显著增大(P<0.05)。三个小区的平均径流率在滑坡后增大了4.0—13.1倍,其平均含沙量和产沙率在滑坡后分别增大了9.9—54.9倍和70—841倍。研究结果有助于加深了解植被沟坡的侵蚀产沙机理,并为浅层滑坡防治提供科学依据。Vegetation restoration is an important measure to prevent and control soil erosion on the Loess Plateau,but shallow landslides induced by rainfall occur frequently on the revegetation slopes,affecting the process of runoff and sediment production in the watershed.In order to quantify the impact of shallow landslides on the process of runoff and sediment and to study the difference in runoff and sediment yield before and after the landslide occurrence,the field simulated rainfall tests were carried out on the grasscovered slope in the Wangdonggou watershed on the Loess Plateau.Based on the field investigation,each experimental plot was 25 m long and 2.5 m wide,and the slope was 35°—40°.Rainfall intensity was 60 mm/h,rainfall time was 90 min,representing a typical heavy rainfall on the Loess Plateau.After the shallow landslide occurred,another rainfall test was carried out,and then the rainfall was stopped.Runoff and sediment samples were collected at the plot outlet at 5 minute intervals from the beginning of the rainfall.After the test,a 100 cm~3 ring knife was used to collect soil samples from different soil layers(10 cm,30 cm,50 cm)in the experimental plot to determine soil bulk density,soil porosity,and the saturated hydraulic conductivity.Three soil samples were taken from each layer.The drying method was used to determine the soil bulk density and soil porosity,and the doublering knife method was used to determine the saturated hydraulic conductivity.The results show that:(1)the depth of the shallow landslide on the grass cover slope induced by extreme rainfall was 14—36 cm,which was consistent with the shallow landslide depth(less than 50 cm)caused by the natural heavy rainfall.The shallow landslide depth was significantly correlated with the vegetation root depth.(2)There were significant differences in the physical properties between upper layer(rootsoil composite)and the lower layer of the landslide surface(P<0.05).The bulk density of the lower layer of the landslide surface was 20.6%—26.0%higher

关 键 词：黄土高原 浅层滑坡 极端降雨 径流 侵蚀产沙 植被恢复 

分 类 号：S157.1[农业科学—土壤学]