Research About The Chrarcteristics Of Tertiary Spatial Structure Of Southern NingXia And Its Influence On Groundwater Quality

The southern Ningxia is one of the most deficient region of water resources, due to shortage of fresh water resources, the economic development makes slow progress in the region, the people living standard is low, the reason for fresh water resources shortage is that Tertiary geologic strata are extensively distribute on the area, and contains large quantity easily dissolve salt, and also the argillaceous ingredient content are large in the stratum. This article, with Xiji County of southern Ningxia as the example, discusses Tertiary strata's influence on the local ground water.First of all, the paper deals with the evolution process of Tertiary sedimentary in Xiji Country and provides the sedimentary litho-phase maps of various seages. during the most time of Tertiary, Xiji was in the inland lake basin and salt deposited in the lake bottom due to the dry climate, with a result that ground water in the stratum shows high content of salt. With the application application of Mapinfo, Arcview GIS and FEFLOW, and based on the bore hole drilling data, the distribution extent and thickness of the Tertiary have been analyzed and the stratum spatial model has been established. In Xiji, the Hongliugou Formation is only distributed in whole area, while the Ganhegou Formation is only distributed in the area west of Yueliangshan mountain. The Qingshuiping Formation is the thickest, about 400m on average and the sikouzi Formation is the thinnest. Moreover, with comprehensive statistical method, the interrelation between the sample and index of groundwater in Tertiary.In addition, the effect of Tertiary strata on groundwater quality has been analysed qualitatively. Because the content of soluble salt in Tertiary water bearing formation is high, so a great amount of salt will enter groundwater and pollute groundwater. This type of groundwater recharges Quaternary confined groundwater and made water quality deteriorate. At last, the suggestion for groundwater exploitation and utilization have been put forward.