鄂尔多斯高原地下水与植被盖度的相互影响  

INTERACTIONS BETWEEN GROUNDWATER AND VEGETATION COVERAGE IN ERDOS PLATEAU

作　　者：王旭升[1] 万力[1] 齐蕊[2] 蒋小伟[1] 黄金廷[3] 金晓媚[2] 梁四海[2] 

机构地区：[1]中国地质大学(北京)教育部地下水循环与演化重点实验室,北京100083 [2]中国地质大学(北京)水资源与环境学院,北京100083 [3]中国地质调查局西安地质调查中心,西安710054

出　　处：《第四纪研究》2014年第5期1013-1022,共10页Quaternary Sciences

基　　金：国土资源公益性行业科研专项项目(批准号:201311076);教育部新世纪人才计划项目共同资助

摘　　要：鄂尔多斯高原位于我国干旱-半干旱过渡带,发育毛乌素沙地和库布其沙漠,其生态环境对地下水有较强的依赖性.利用2005～2012年地下水观测数据、2008年8月中下旬MODIS NDVI数据和同期陆面蒸散量评估数据,以NDVI为基础定义植被相对盖度,本文研究了鄂尔多斯高原植被盖度与浅层地下水的依赖关系,以及植被盖度对地下水补给的影响.研究区植被盖度的统计特征近似符合Gamma随机分布函数,当地下水埋深小于10m时,其均值和峰值明显随地下水埋深增大而减小,且峰值对地下水更敏感.植被盖度同时受到气候条件和地下水的影响,呈斑块状分布.蒸散系数（实际蒸散强度与蒸发潜力的比值）随植被相对盖度的增大而升高,两者的依赖关系可以近似表示为分段线性函数.基于此近似关系,本文估算了鄂尔多斯高原地下水净补给强度的多年平均值.结果显示植被稀疏的沙地有利于地下水补给,而植被生长较为旺盛的低洼地带因蒸发强烈形成地下水的排泄区.地下水、植被和陆面蒸散之间存在耦合关系.Erdos Plateau （37°31′ ～40°45′N,106°24′ ～ 11 1°07′N） is an area （ca.13× 104km2） in the arid and semiarid region in China,including Mu Us and Kubuqi deserts,where the ecological environment is strongly dependent on groundwater.The landscape in Erdos Plateau is mainly characterized by sand dunes and shurblands.Shallow groundwater in the sandy sediments is an essential source of water for plants.In this study,the interactions between vegetation coverage and groundwater are investigated.987 observation wells with shallow groundwater data between 2005 and 2012 were collected from more than 1200 wells and boreholes in the whole Erdos Plateau.Most of the wells were located in the middle （Otoqo Qi and Uxin Qi） and south （Yanchi city） areas of the plateau,representing the groundwater conditions in the Mu Us Desert.Groundwater depth in wells was generally measured in the summer （from June to September）.The contours of groundwater level in Hailiutu River catchment （a catchment in Erdos Plateau,ca.2600km2） was built based on these observation data and applied to construct 500-m resolution raster data of groundwater depth.MODIS NDVI data in the late of August in 2008 were collected to estimate the relative vegetation coverage （CNDVI） with 500-m resolution.The evapotranspiration coefficient,defined as the ratio of the actual evapotranspiration rate to the potential evaporation rate,was estimated for the same period and resolution using the evapotranspiration data assessed with remote sending method.The CNDVI value shows an inhomogeneous distribution in the study area that affected by both climate and groundwater.It was found that the statistic property of CNDVI can be approximated by the Gamma distribution and the key parameters are dependent on groundwater depth.When depth to water table is less than 10m,the average and maximum CNDVI values significantly decrease with increase of groundwater depth,especially for the maximum value.The average CNDVI value approximates to 20％ and sho

关 键 词：地下水 植被指数 补给 蒸散 相互作用 鄂尔多斯高原 

分 类 号：P641.139[天文地球—地质矿产勘探] Q948[天文地球—地质学]