摘要
切沟是黄土高原常见的地貌形态,是流域产沙的主要来源,而植被常被看作抑制切沟发育的关键因子,为探究退耕还林(草)工程以来切沟发育速率的特征,本研究使用吴起研究区间隔6年的2期同时相Quick Bird影像和分辨率为5 m的DEM,应用GIS技术分析研究区内的切沟发育速率及其影响因子。结果表明:2007—2013年研究区内小流域的年均切沟面积变化比例均<0.5%,其中无淤地坝小流域的年均切沟面积变化比例为0.13%,淤地坝小流域的年均切沟面积变化比例为0.12%;相关分析表明:在该研究区内沟间地的植被覆盖度是影响切沟发育的最主要影响因子;通过对30个无淤地坝小流域的年均切沟面积变化比例和植被覆盖度做非线性回归(R2=0.713)可得,当植被覆盖度>0.6时,其抑制切沟发育的效果最明显;方差分析表明:其他影响因子值(植被覆盖度和地貌因子)相近的条件下,有无淤地坝的6组小流域切沟发育速率无显著差异。总之,沟间地植被覆盖度是影响切沟发育的主要影响因子,而淤地坝对发育在沟缘线上的切沟无显著影响,促进植被恢复有利于抑制切沟发育。
[Background] Gully erosion is one of the major forms of soil erosion threatening land resources on the Loess Plateau. Gully development is a threshold-dependent process controlled by a wide range / of factors and vegetation is frequently considered as one of the key factors to control gully erosion.[Methods] In order to give great insight to gully development characteristics since the project of returning cropland to forest（ grass） in 1999,30 small catchments without check dam and 6 catchments with check-dams were selected in Wuqi County of northern Shaanxi province,which is in the second subzone of loess hilly region with active gully erosion. Based on two same time phases Quick Bird images of0. 61 m-resolution with a 6-year interval and digital elevation model（ DEM） with pixel size of 5 m,valley shoulder lines in the studied small catchments were extracted by visual interpretation and the rates of gully area change were estimated with GIS technology. Average vegetation coverage,local slope,upslope drainage area,land uses,and the change rates of gully area from 2007 to 2013 were calculated to assess the factors influencing gully growth. [Results] 1） Annual average growth rate of gully area in all 36 studied catchments was less than 0. 5%,with averagely 0. 13% in the catchments without check dam and0. 12% in the catchments with check dams. 2） Pearson＇s correlation analysis among gully growth rates and the factors influencing gully erosion showed that vegetation coverage on inter-valley was of the most importance with r = 0. 619 at significance level of 0. 01,followed by proportion of shrub land. The geomorphologic factor（ AS2,where S is local slope gradient and A is drainage area）,which was considered the predictor of gully initiation,was not related significantly to gully area growth rates owing to high vegetation coverage. 3） The vegetation coverage increased by 28. 7% and the proportion of woodland and grassland area increased to 94. 5% from 2007 to 2013 in the studied area. Non-linear regression curve between growth rates of gully area and vegetation coverage in 30 catchments without check dam,with R2 was 0. 713,indicated that vegetation coverage larger than 60% in inter-valley significantly inhibited the gully erosion. 4） Analysis of variation showed that there was no significant difference of the gully area growth rate between 6 pairs of catchments with and without check dams（ with the similar vegetation coverage and geomorphology）,indicating that check dam in the area of gully presented no significant effect on the gully development on valley shoulder line. [Conculsions] This study indicates that vegetation restoration owing to the project of returning cropland to forest or grassland reduced gully growth rate significantly, which could provide reference for understanding gully development mechanism and help to select the effective ecological measures to control gully erosion.
出处
《中国水土保持科学》
CSCD
北大核心
2016年第4期18-25,共8页
Science of Soil and Water Conservation
基金
国家自然科学基金"黄土丘陵区退耕还林对切沟发育和侵蚀过程的影响机制"(41271301)
作者简介
杨松（1990-），男，硕士研究生。主要研究方向：自然资源监测与管理。E-mail：564838726@qq．com
张岩（1970-），女，副教授，硕士生导师。主要研究方向：土壤侵蚀和水土保持。E-mail：zhangyan9@bjfu．edu．cn
