西宁盆地黄土区不同草本植物和坡形条件下坡面产流产沙特征

The Characteristics of Runoff and Sediment Yield on Slope Surface under Different Herbs and Slope Shapes in Loess Regions of Xining Basin

中文关键词:  西宁盆地  寒旱环境  模拟降雨  坡 形  草本植物  产流产沙

英文关键词:Xining Basin  Frigid and arid environment  Rainfall simulation  Slope shape  Herbs  Runoff and sediment yield

中文摘要:

      为进一步研究不同草本植物和边坡坡面形态对坡面产流产沙的影响,以西宁盆地毛鸡湾流域长岭绿化区作为试验区,设计了直形和阶梯形2种坡形,选取3种优势草本老芒麦(Elymus sibiricus Linn.)、垂穗披碱草(Elymus nutans Griseb.)和细茎冰草(Agropyron trachycaulum Linn.Gaertn.)作为试验供试种,通过人工模拟降雨试验,探讨了种植不同草本和坡形条件下,边坡坡面的产流、产沙和入渗特征。结果表明,在直形边坡中,裸坡坡面的产流时间小于种植草本植物坡面,且垂穗披碱草坡面和老芒麦坡面的形成产流时间相对较长,为4 min。与直形边坡相比,垂穗披碱草阶梯形坡面产流时间相对最长,为8 min；在直形边坡中,垂穗披碱草坡面和老芒麦坡面累积径流量、累积产沙量和径流系数相对最小,分别为51.42 L/min、160 g、14.98%,51.25 L/min、210 g、14.93%,细茎冰草坡面的累积径流量、累积产沙量和径流系数分别为96.97 L/min,700 g,28.25%；垂穗披碱草坡面和老芒麦坡面稳定入渗速率相对最大,其值为0.38~0.44 mm/min,细茎冰草坡面的稳定入渗率为0.29~0.36 mm/min。在阶梯形边坡中,垂穗披碱草坡面的累积径流量、累积产沙量和径流系数相对最小,其值分别为5.62 L/min、110 g、1.64%,且垂穗披碱草坡面入渗速率相对最大,为0.50~0.52 mm/min,这反映出种植草本植物可增大其坡面的入渗率,有效减少坡面径流和土壤侵蚀,其中垂穗披碱草和老芒麦的固土保水作用相对最为显著；且与直形边坡相比,阶梯形边坡能有效延长坡面土壤水分入渗时间,减少坡面地表径流,从而提高边坡坡面土壤的抗侵蚀能力。

英文摘要:

      To deeply investigate the influence of different herbs plants and slope shapes on runoff and sediment yield,Changling green zone of Maojiwan catchment in Xining city was selected as the testing area.Two slopes were designed to be straight-shaped and step-shaped and three types of local vegetation were chosen as the test species(Elymus sibiricus Linn., Elymus nutans Griseb.and Agropyron trachycaulum Linn.Gaertn.).The characteristics of runoff,sediment yield and infiltration of the slope were studied under the different herbs and slope shapes for artificial rainfall simulation tests.The results show that the initial runoff time of the denuded slope is shorter than that of the slopes planted with herbs and the formation time of runoffs on slope covered with Elymus sibiricus Linn and Elymus nutans Griseb.is longer,which is 4 minutes.Compared with the straight-shaped slope,the stepped-shaped slope planted with Elymus nutans Griseb.has the longest runoff time,which is 8 minutes.In the straight-shaped slope,the cumulative runoff,cumulative sediment yield and runoff coefficient of the slopes planted with Elymus nutans Griseb.and Elymus sibiricus Linn.are the smallest,the values being 51.42 L/min,160 g,14.98% and 51.25 L/min,210 g,14.93% respectively.The cumulative runoff,cumulative sediment yield and runoff coefficient of the slope planted with Agropyron trachycaulum Linn.Gaertn.are 96.97 L/min,700 g,28.25%.And the infiltration rate of the slopes planted with Elymus nutans Griseb.and Elymus sibiricus Linn.is relatively larger and the stable infiltration rate is 0.38~0.44 mm/min,while the stable infiltration rate of the slope planted with Agropyron trachycaulum Linn.Gaertn.is lower and being 0.29~0.36 mm/min.In the step-shaped slope,the cumulative runoff,cumulative sediment yield and runoff coefficient of the slopes planted with Elymus nutans Griseb.are the relatively smallest and with the values 5.62 L/min,110 g and 1.64% respectively,and the infiltration rate of the slopes planted with Elymus nutans Griseb.is the largest,with the value 0.50~0.52 mm/min,which indicates that planting herbs can increase the infiltration rate of the slope surface,effectively reduce slope runoff and soil erosion,and has a good effect of soil and water conservation.Moreover,Elymus sibiricus Linn.and Elymus nutans Griseb.play the most significant role in soil and water conservation and compared with straight-shaped slope,step-shaped slope can effectively extend the soil moisture infiltration time on the slope surface and reduce the runoff and sediment yield on the slope surface,and furthermore improve the erosion resistance of the slope soil.