Field experiments on quantifying the contributions of Coreopsis canopies and roots to controlling runoff and erosion on steep loess slopes  

作　　者：GONG Yu-wei YU Hai-jun TIAN Pei GUO Wen-zhao CHEN Lin SHEN Ding-tao 

机构地区：[1]Key Laboratory for Geographical Process Analysis&Simulation of Hubei Province,Central China Normal University,Wuhan 430079,China [2]China Institute of Water Resources and Hydropower Research,Beijing 100038,China [3]State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau/Institute of Water and Soil Conservation,Northwest A&F University,Yangling 712100,China [4]Department of Environmental Sciences,University of California Riverside,Riverside,CA 92521,USA

出　　处：《Journal of Mountain Science》2023年第5期1402-1423,共22页山地科学学报（英文）

基　　金：supported by the National Natural Science Foundation of China(41907061);the Natural Science Foundation of Hubei province,China(2021CFB550);the joint fund for regional innovation and development of NSFC(U21A2039)。

摘　　要：Grass recovery is often implemented in the loess area of China to control erosion.However,the effect mechanisms of grass cover on runoff erosion dynamics on steep loess hillslopes is still not clear.Taking the typical forage species(Coreopsis)in semiarid areas as subject,this study quantified the effects of canopies and roots on controlling slope runoff and erosion.A series of field experiments were conducted in a loess hilly region of China.Field plots(5 m length,2 m width,25°slope gradient)constructed with three ground covers(bare soil;Coreopsis with intact grass;only roots of Coreopsis),were applied with simultaneous simulated rainfall(60mm h^(-1))and upslope inflow(10,30,50,70,90L min^(-1)).The results showed that compared with bare soil,intact grass significantly reduced runoff and soil loss rates by 16.6% and 62.4% on average,and decreased soil erodibility parameter by 66.3%.As inflow rate increased,the reductions in runoff and soil loss rates increased from 2.93 to 14.00 L min^(-1)and 35.11 to 121.96 g m^(-2)min^(-1),respectively.Canopies relatively contributed 66.7% to lowering flow velocity,turbulence,weakening erosive force and increasing hydraulic resistance.Roots played a predominant role in reducing soil loss and enhancing soil antierodibility,with relative contributions of 78.8% and 73.8%.Furthermore,the maximum erosion depth reduced by Coreopsis was at the upper slope section which was previously eroded the most.These results demonstrated the efficiency of Coreopsis cover in controlling runoff and erosion on steep loess slopes,especially under large inflow rates and at upper slope sections.We suggest protecting Coreopsis with intact grass at upper slope sections,while the aboveground grass biomass can be used for grazing or harvesting at middle and lower slope sections,with roots reserved.

关 键 词：Steep loess hillslopes Soil erosion Rill development Runoff hydraulics Spatial variations Coreopsis 

分 类 号：P333[天文地球—水文科学] S157.1[水利工程—水文学及水资源]