额济纳绿洲地下水动态与植被退化关系的研究

Study on the Relation between Groundwater Dynamics and Vegetation Degeneration in Erjina Oasis

根据“九五”期间承担的原地质矿产部重点项目和科技部攻关项目的研究成果 ,对额济纳绿洲地下水动态和均衡特征进行了全面分析 :近年来额济纳平原地下水补给量小于排泄量 ,含水层储量每年减少 92 .5× 10 6m3 ,地下水处于负均衡状态 ;中深层地下水动态变化不显著 ,潜水动态变化复杂 ,水位普遍下降 ,部分地区降幅在 2 .0～ 3.0m .受地下水动态变化影响 ,绿洲区植被严重退化 ,胡杨林、柽柳林等地表植被大面积死亡 ,土地沙漠化加剧 ,绿洲的主要生态功能衰退 .在分析地下水动态变化对绿洲植被影响的基础上 ,提出了通过改变水资源利用方式 ,调整地下水动态 。

Erjina oasis is a alluvial plain of lower reaches of Heihe River in Erjina Banner of lower reaches of Heihe River . Affected by natural and human factors , vegetation of the oasis degenerated greatly ,and its ecological function declined ,which made the oasis being at the edge of collapse .Based on the research achievements of the major project Groundwater Exploration and Ecological Environment and Geological Investigation in Erjina Plain ofNorthwest groundwater Special Plan from the original Geology and Mineral Department and the major project of Study on Ecological Environment Comprehensive Control and Moderate Use in Erjina Desert Oasis from the Science and Technology Department, the paper gave rounded analysis to groundwater dynamics and groundwater balance characters : groundwater recharge capacity is less than discharge capacity and groundwater storage capacity reduced 92.5×10\+6 m 3 making it to be negative balance ;recharge in middle and deep layers is not obvious while phreatic fluctuation is complicated resulting a general decline of groundwater level which some places declined 1～2 m. Compared the area from the result of Forest Resources Investigation 2002 with the area 30 years ago, Diversifilious Popular forest reduced 20 600 hm 2 , reaching 29 400 hm 2 now, and Chinese Tamarisk forest and Saxaul forest reduced significantly .Meanwhile, other desert plant species such as \%Mongolian Calligonum, Siberian Nitraria\% and \%Desert Wormwood\% died in large areas, leading to a 20%～50% decline of vegetation coverage .The main natural factors causing vegetation degeneration in the oasis are groundwater dynamics changes and groundwater table decline originated from the reduced discharge capacity of Heihe River and the balance irregularity of groundwater .Thus keeping a certain amount of river discharge capacity is the base of stability and rehabilitation of the oasis vegetation for the Erjina Plain groundwater system dependent mostly on the outer runoff recharge as well as effective measures of changing the using way of water resources and regulating groundwater dynamics .