寒旱环境黄土区植物护坡原位模拟降雨试验研究

Experimental Research on Slope Protection with Vegetation under Situ Rainfall Simulation in Cold and Arid Environment of Loess Area

在自建试验区内为研究植物护坡水文效应，本项研究采用野外模拟降雨试验的方法，分别对种植柠条锦鸡儿（Caragana kor shinskii Kom．）、霸王（Zygophyllum xanthoxylon Bunge Maxim．）2种灌木植物边坡和种植垂穗披碱草（Elymus nutarts Griseb．）、细茎冰草（Agropyron trachycaulum Linn．Gaertn．）2种草本植物边坡，以及作为对照组未种植植物的裸坡开展相同试验条件的模拟降雨试验。试验结果表明，在相同试验条件下裸坡的稳定径流量和泥沙量均相对较大其值为450．0～475．0ml／min，8．28～8．36g／min；种植霸王、柠条锦鸡儿边坡稳定径流量和泥沙量为307．0～355．5ml／min，3．12～4．07g／min；种植细茎冰草边坡、垂穗披碱草边坡稳定径流量和泥沙量为24．0～41．3ml／min，1．52～2．40g／min，该试验结果说明了坡面产生的稳定径流量和稳定泥沙量与边坡的覆盖度之间呈负相关关系以外，还进一步反映出种植草本植物的边坡其坡面产生的稳定径流量、泥沙量则显著小于种植灌木植物边坡，即种植灌木边坡其坡面产生稳定径流量、泥沙量分别是种植草本边坡的1．338～1．466倍、2．054～2．654倍；裸坡坡面以下O一20cm处及坡面以下20-40cm处含水率增幅分别为38．94％，11．08％；种植柠条锦鸡儿、霸王边坡坡面以下相同深度处的a层、b层含水率增幅为42．24％～44．19％，10．63％～11．76％，种植垂穗披碱草、细茎冰草边坡坡面以下相同深度处的a层、b层含水率增幅为47．27％～48．1l％，13．98％～14．74％，坡面以下40～60cm处的（c层）含水率变化相对不显著，表明在边坡种植的草本和灌木植物，在降雨坡面雨水人渗的过程中，阻止和减少了坡面径流的形成，同时亦反映出生长草本植物的边坡其阻止和减少坡面径流形成的作用相对显著于灌木植物；裸坡的径流系数为63．40％，种植柠条锦鸡儿和霸王边坡径流系数则分别为18．00％和20．33％，细茎冰草和垂穗披碱草径流系数分别为6．57％和1．71％，草本植物边坡径流系数相对最小，反映出草本植物其抵挡坡面雨水冲刷和侵蚀以及抑制地表径流作用等方面较灌木植物显著。

To study the hydrological effects of slope protection with vegetation, we carried out the method of situ rainfall simulation on the slopes covered by two shrubs Caragana korshinskii Kom, Zygophyllum xan- thonylon （Bunge） Maxim and on the slopes planted with 2 herbs Elyrnus nutans Griseb, Agropyron trachy- caulum （Linn.） Gaertn, as well as on the control slopes without vegetation under the same test conditions. The results show that the stable runoff and sediment flux of the bare slope under the same test conditions are relatively bigger, the values are 450.0～475.0 ml/min and 8.28～8.36 g/rain, respectively; the stable runoff and sediment fluxes of the slopes planted with Zygophyllum xanthonylon, Caragana korshinskii are 307.0～ 355.5 ml/min and 3.12～4.07 g/min, respectively; the stable runoff and sediment fluxes of the slopes plan-ted with Agropyron trachycaulum, Elymus nutans are 24.0～41.3 ml/min and 1.52～2.40 g/mm, respec- tively. The data show that stable runoff and sediment flux are negatively related with slope vegetation cover- age. Further studies show that the stable runoff and sediment flux of the slopes planted with herbs are signif- icantly less than the slopes planted with shrubs, and the stable runoff and sediment flux of the slopes planted with shrubs is 1. 338～1. 466 times, 2. 054～2. 654 times of the slopes planted with herbs. The the increment rates of soil moisture contents in the layer（0—20 cm） and the layer（20—40 cm） are 38.94% and 11.08%, respectively; at the same depth, the increment rates of soil moisture contents of the slopes covered with Ca- ragana korshinskii, Zygophyllum xanthonylon are 42.24%～44.19% and 10.63%～11.76%, respectively; and those of the slopes planted with Elymus nutans, Agropyron trachycaulum of at the same depth are 47.27%～48.11% and 13.98%～14.74%, respectively; the soil moisture content change in the layer （40— 60 cm） is not significant. The data show that planting vegetation in the slopes can effectively prevent and re- duce the slope runoff generation during the process of rainfall infiltration, and the effect of herh is more sig- nificant than that of the shrub in terms of reducing the runoff yield. The runoff coefficient of bare slope is 63.40 %, for slopes planted with Caragana korshinskii and Zygophyllum xanthonylon the runoff coefficients are 18.00% and 20.33%, tans are 6.57% and 1.71 than that of the slopes wi respectively and for slopes planted with Agropyron trachycaulurn and Elymus nu-tans are 6.57% and 1.71%, respectively. The runoff coefficient of the slopes with herbs is relatively less than that of the slopes with shrubs, which indicates that the inhibitory role of herbs in resisting rain erosion and soil erosion and surface runoff is more significant than shrubs.