【作者】 孙芳强；

【导师】 苏生瑞；

【作者基本信息】 长安大学 ， 地质工程， 2010， 博士

【摘要】 鄂尔多斯盆地是一个地跨陕、甘、宁、内蒙古四个省(区)的大型沉积盆地。都思兔河流域位于鄂尔多斯盆地西北部,行政区划隶属于内蒙古自治区鄂尔多斯市鄂托克旗。前人通过多种手段从某一局部或某一侧面研究了都思兔河流域地下水系统,还未从流域角度研究都思兔河流域的地下水循环规律及地下水开发利用所引起的生态环境效应。本文以鄂尔多斯白垩系系盆地都思兔河流域为研究区,应用现场水文地质调查、水文地质钻探及抽水试验、Packer系统定深取样技术、水化学及同位素等多种方法,获得了都思兔河流域最新的地下水流场、不同深度地下水水化学场资料。在此基础上综合利用地下水动力学、水化学及同位素方法对都思兔河流域不同级次的地下水循环深度进行厘定,进而得出区内地下水的循环模式；利用研究区不同深度的地下水水化学测试结果,进行地球化学特征定性分析,通过分析浅层、中层地下水的水化学空间分布规律,典型水流路径上地下水水化学组分沿程变化特征,研究不同深度地下水的循环规律；并研究了地下水开发利用所引起的生态环境效应,提出了地下水资源的保护措施。都思兔河流域含水层系统可分为第四系风积、冲湖积砂层孔隙含水层系统和白垩系碎屑岩裂隙孔隙含水层系统,而白垩系碎屑岩裂隙孔隙含水层系统是都思兔河流域地下水含水层系统的主体,包含有罗汉洞组含水层、环河组含水层、洛河组含水层三个含水层子系统；都思兔河流域地下水的天然补给源主要为大气降水入渗补给；地下水排泄方式主要有潜水蒸发蒸腾排泄、地下水向河流溢出排泄、人工开采排泄及侧向断面径流等,潜水的蒸发蒸腾是最主要的排泄方式；区内地下水的动态类型分为入渗-蒸发型、入渗-径流型及入渗-开采-径流型根据Packer系统及分层试验孔取得的地下水水化学及同位素的空间变化特征分析,结合水动力的空间变化特征分析,都思兔河流域埋深200-250m为浅层地下水循环与中层地下水循环的分界带,埋深600m为中层地下水循环与深层地下水循环的分界带。浅部循环模式：地下水交替强烈,更新能力强,浅层地下水的年龄均在50年以内;中部循环模式：影响宽度在40-80km左右,是地下水的较积极交替带,水量较丰富,地下水年龄一般小于5000年,局部为5000-20000年之间；深部循环模式：循环的深度达1000m。地下水的径流交替十分缓慢,地下水的14C年龄一般13000-15000年,在地表分水岭地区小于13000年。从区内中、浅层地下水水化学的水平分带规律来看,中、浅层地下水交替积极,地下水化学场水平分带明显。地下水反映了区内地下水的补排条件,即研究区东部及北部地势较高,水位埋深相对较大,水力坡度较陡,地下水交替积极,水岩相互作用不够充分,为地下水溶滤带；随着地下水逐渐向下游流动,受蒸发浓缩作用及阳离子交换等水岩作用影响,水岩作用充分,TDS含量不断增大,地下水中的可溶性含盐量增高,形成高矿化度地下水,水化学类型主要为SO4·Cl型水,在布隆庙以西区域形成排泄区。通过分析浅层、中层地下水的水化学及同位素空间分布规律,典型水流路径上地下水水化学组分沿程变化特征,得出浅层地下水、中层地下水均是向都思兔河汇流,都思兔河流域的地下水为一向中心汇流的径流特征。与浅层地下水比较,中层地下水经历了更为复杂的演化过程,发生了更强烈的水岩作用。在分析区内生态环境现状的基础上,结合植被类型、植被生长的适生水位、植被分布特征及地下水位埋深条件将区内现状生态环境划分为生态环境相对脆弱区、生态环境一般脆弱区、生态环境中等脆弱区及生态环境严重脆弱区。采取优选的地下水的开采方案,预测开采20年后,区内地下水流场未发生较大变化,区内未形成明显的降深漏斗。三北羊场、查汗台阁及嘎沙图三个拟选水源地地下水开采对生态环境影响的敏感程度不明显；而包乐浩晓、巴彦布拉格及好勒保勒吉拟选水源地地下水开采地下水位埋深增加幅度不大,相互影响较小。拟选水源地地下水开采对都思兔河流的径流量影响较小。由于研究区内生态环境比较脆弱,因此,在能源开发的同时应加强对地下水资源的保护。在确定合适的开采原则基础上,控制开采量,加强水源地保护。更多还原

【Abstract】 Ordos basin is a large scale groundwater basin overlapping Shaanxi, Gansu, Ningxia and Inner Mongolia provinces or autonomous regions. Dusitu river is located in the northwestern of Ordos basin and belongs to Etuoke Qi of Inner Mongolia autonomous regions. Although the groundwater system had been researched by previous researchers from some local regions or a certain side, but groundwater circulation and environment effect influenced by groundwater utilization haven’t been researched from the point of the basin. The latest date of groundwater flow field and hydrochemistry field is obtained in study area,using Various methods including hydrogeology investigation, hydrogeological drilling and pump test, Packer depth sampling, hydrochemistry and isotope. On the basis of the groundwater dynamics, hydrochemistry and isotopic features of groundwater, groundwater circulation depth and circulation patterns of the different patterns have been defined to groundwater system in Dusitu river. Circulation law of different deep groundwater have been studied by means of hydrochemistry distribution feature of shallow and middle groundwater and the change of the ratio of molar concentration along the groundwater passes. Environment effect influenced by groundwater utilization have been studied and the protecting measures of groundwater resources have also been suggested.The groundwater aquifer system in Dusitu river can be divided into Wind-drift and alluvial-laustrine pore aquifer system in Quaternary sand and clastic pore-fissure groundwater aquifer system in Cretaceous rocks, which is dominant for aquifer system in Dusitu river, including Luohandong, Huanhe, Luohe water-bearing layers aquifer system. Precipitation infiltration recharge is the main resource to recharge groundwater. And groundwater is discharged by phreatic evaporation, overland flow, artificial exploitation, lateral runoff, while groundwater is discharged dominantly by phreatic evaporation. The dynamic types of groundwater can be divided into three types including infiltration- evaporation, infiltration-runoff, infiltration - exploitation -runoff.According to hydrochemistry and isotopic data obtained by Packer depth sampling and jigging pump test, the hydrochemical and isotopic features of groundwater has been studied as well as dynamics features of groundwater in Dusitu river. The depth of 200 to 250 meters is the boundary belt between the shallow circulation pattern and middle circulation pattern. The depth of 600 meters is the boundary line between the middle circulation pattern and deep circulation pattern. The shallow circulation pattern is characterized by fast circulation, high renewal capability and the groundwater age of less than 50a. Middle circulation pattern is characterized by relatively fast circulation, relatively abundant water resources the groundwater age of less than 5000a, and 5000 to 20000 a in local scope. Deep pattern is characterized by low flow velocity, large circulation depth of 1000m and groundwater age of 13000 to 15000a, less than 13000a in ground watersheds.The shallow and middle groundwater are characterized by by fast circulation from horizontal zonal characteristic of hydrochemistry, and the chemical fields of local groundwater is horizontal zonation obviously. The east and north of study area is seepage zonation of groundwater with high topography, deep groundwater depth, large percolation gradient, fast circulation and less water-rock interaction. While the groundwater moves to the lower reaches, total dissolved solids of groundwater is more, the soluble salt content of groundwater increases obviously and the hydrochemical type is mainly SO`Cl with high mineralization for the discharge area west to Bulongmiao. On the basis of hydrochemical and isotopic features of shallow and middle groundwater and the change of the ratio of molar concentration along the groundwater passes, shallow and middle groundwater moves towards Dusitu river. Middle groundwater have gone through more complicated evolution course and stronger water-rock interaction than shallow groundwater.On the basis of analysis of current situation for ecological environment with vegetations types, suitable groundwater depth for vegetations, distribution features of vegetations and groundwater depth condition, current situation vulnerability of ecological environment can be divided into four types, that is, relative fail area, mild fail area, medium fail area and serious fail area. The groundwater flow field forecasted will not change too greatly after 20 years, and the groundwater depression forecasted will not obvious in study area, if adapted Optimum exploitation scheme. The influence to ecological environment is not obvious, which is caused by groundwater exploitation for Sanbeiyangchang, Chahantaige and Gashatu well fields. And after Baolehaoxiao, Bayanbulage and Haolebaoleji well fields having been exploited, groundwater depth increase less and the interaction between them is small. As the ecological environment is fragile, the protecting measures of groundwater resources should be taken. while groundwater is exploited, if adapted optimum exploitation scheme, the protecting measures of well fields should be taken.更多还原