坡面尺度林地植被对地表径流与土壤水分的影响初步研究

通过定位观测以及对两个天然坡面有林地径流场和无林地径流场进行对比,以2003年、2004年实测的降雨、径流数据分析研究区域内降雨特性、地表径流产生的过程和机制,并结合1996～1998年相关数据,初步研究了林地植被对地表径流的影响.结果表明:无论是有林地还是无林地,地表径流系数随降雨量增大而增大.有林地径流系数小于对应的无林地径流系数.植被对地表径流有不同程度的削减作用,径流削减率与降雨量大小并不是单一的线性(递增、递减)关系:当降雨量小于73.04mm时,植被对地表径流系数的削减率随降雨量增加而增加,当降雨量大于73.04mm时,植被对地表径流系数削减率随降雨量增加降低.植被能够削弱地表径流的峰值,延缓峰值出现的时间,使得径流历时加长.植被对地表径流削减率的大小和降雨量大小关系不是单一的线性(递增、递减)关系:当降雨量小于73.04mm时,植被对洪峰的削减率随降雨量增加而增加,当降雨量大于73.04mm时,植被对洪峰的削减率随降雨量增加而呈总体下降趋势.以2004年为例,比较有林地与无林地在三种相同坡位情况下的土壤含水量大小关系,结果:坡上位土壤水分有林地大于无林地,而坡下、坡中无林地土壤水分大于有林地.说明林地植被能够拦蓄、调节径流,起到涵养水源、在空间和时间上合理配置土壤水分、提高生态效益的作用.

Preliminary Study of the Influence of Vegetation in Natural Forested Land Runoff Plots Slope on Ground Runoff

By means of sites measurement and comparison,using the data of precipitation and runoff measured continuously in 2 years(2003、2004),the rainfall characteristic and ground runoff generation mechanism are analyzed,together with the relative data in the year 1996～1998.Preliminary study about the influence of vegetation on ground runoff is carried out.The results show that ground runoff coefficient increases with rainfall,the ground runoff coefficient of forested land is less than that of non-forested land.Vegetation can reduce the ground runoff coefficient more or less.Reduction rate of runoff coefficient is not single linear to rainfall:when rainfall ≤73.04 mm,reduction rate of runoff increases with rainfall;rainfall ≥73.04 mm,it decreases with rainfall.At the same time,vegetation can reduce the flood peak,postpone the appearance of flood peak,prolong the runoff period as well.The flood peak reduction is not single linear to rainfall:rainfall ≤73.04 mm,reduction rate of flood peak increases with rainfall;rainfall ≥73.04 mm,it decreases with rainfall.The data of soil moisture in 2004 shows that the forested vegetation has an obvious effect on absorbing and preserving water,as well as improving the ecology benefit.