民勤绿洲地下水环境动态研究

根据民勤绿洲1999～2008年51眼地下水位观测井资料和2010年采集的30个地下水水样资料,利用传统统计学和地统计学分析方法对该地区新时期地下水位时空变化动态和地下水化学特性进行了研究。结果表明:民勤绿洲地下水位近10年来总体呈逐年下降的趋势,年均降幅达0.52m;在引黄民调工程、石羊河流域分水方案等政策措施的影响下,2005、2007和2008年地下水位降幅均呈现减小趋势,并在2007年首次出现0.01m的回升;坝区和泉山区地下水位年均降幅较湖区分别高0.23m和0.52m,下降速度明显快于湖区;整个绿洲区地下水平均矿化度为3.34g/L,沿地下水流动方向,地下水化学类型变化较大,由坝区和泉山区南部的SO42--HCO-3-Na+或SO42--HCO-3-Ca2+型淡水-微咸水逐渐变为湖区的SO2-4-C1--Na+-Mg2+咸水-苦咸水。

Groundwater environment variation in the Minqin Oasis

According to the records of 51 observation wells of groundwater table in the Minqin oasis from 1999 to 2008,we investigated temporal and spatial variation of groundwater table.Samples of 30 active water supply boreholes were also collected in 2010 to understand the hydrochemical properties of groundwater.Statistical results indicated that the groundwater table had declined over the past 10 years,with an average decline rate of 0.52 m per year.Under the influences of Yellow River diversion project,water discharge engineering,the decline rate per year of groundwater table was decreased in 2005,2007 and 2008.The decline rates per year of depth to groundwater in Baqu and Quanshan was higher than that of in Huqu,with increments of 0.23m/y and 0.52m/y,respectively.The average TDS(total dissolved solids) in the oasis was 3.34g/L.The hydrochemical types of groundwater were changed along the groundwater flow direction.The dominant anion species of water changed systematically from SO42-HCO3-Na+ or SO42-HCO3-Ca2+ to SO42-C1-Na+-Mg2+ from Baqu and Quanshan to Huqu.