| The Kashgar delta is an important social and economic center in the southern Xinjiang and it is an important node in the Silk Road to South Asia.In this area,the climate is dry,the ecological environment is fragile,the primary water quality is poor,the high sulfate groundwater is widely distributed and the water shortage is prominent,which seriously restricts the social and economic development in the area,and also affects the health of the residents in this area.In recent years,a lot of work has been carried out on the exploration and exploitation of groundwater and freshwater in the high sulfate region.However,it has not been carried out systematically to ensure the actual problem of preventing the invasion of high sulfate water during the process of mining fresh water.Therefore,exploring the causes of high sulfate groundwater and the rational development and utilization of freshwater resources are important issues to be solved in this area.Based on the geological survey of the China Geological Survey and the project of the geological prospecting fund of the Xinjiang autonomous region,this paper aims at the rational exploitation and utilization of underground freshwater resources in the high acid salt region,with the guidance of geological geomorphology,groundwater dynamics and hydrogeochemistry,through field investigation,in situ tracer test,soil column leaching experiment and By means of numerical simulation,the cause of high sulfate groundwater is analyzed,the numerical model of the coupling of groundwater flow and solute transport phase is constructed,and the research on the exploitation and utilization of groundwater resources based on the dual constraints of water quality and ecology is carried out to provide high quality water source support for the sustainable development of the study area.The following awareness and results are mainly achieved:(1)Guided by the theory of groundwater system,according to the hydrogeologicalconditions of the study area,the study is divided into the freshwater groundwater system of kkam River Giz River and the groundwater system of the kziz River Chuck Ma River.The sulphate of shallow groundwater in the groundwater system of the kiz River and Chuck Ma River is exceeding the standard,and there is a small amount of high quality fresh water in the deep groundwater;the sulphate content in the groundwater system of the Ulu Xiaohe River KGI River Kuram river is relatively low,which is in line with the national standard of drinking water and can be used for living and drinking.The formation of the Neogene containing gypsum and other minerals in the front of the mountain is an important source of high sulphate groundwater,and the climatic conditions of drought and the slow velocity of groundwater runoff are the main forming conditions.(2)Through the analysis of groundwater sulphate equilibrium in the study area,it is found that the leaching of soil aeration zone by farmland irrigation is the main input source of groundwater sulfate,and its contribution to the formation of sulphate groundwater is 76.19%.The sulphate carried by the lateral runoff through the sulphate formation in the front of the mountain is a secondary source,and its sulphate groundwater The contribution of the formation is 19.5%.Artificial mining is one of the main sources of sulphate in underground aquifer,accounting for 43.1%.It is seen that human activities such as farmland irrigation and artificial mining have changed the redistribution and enrichment of sulfate in groundwater.(3)On the basis of comprehensive analysis of geological and geomorphic and hydrogeological conditions,the hydrogeological conceptual model of the study area,the numerical simulation model of groundwater flow and the model of groundwater solute migration are established.With the Visual MODFLOW software as the platform,the WHS(stable conjugate gradient method)is used as the operation method,the parameter inversion calculation is carried out by PEST,which ensures the high simulation and reliability of thenumerical model,and lays a foundation for the simulation and prediction of the groundwater dynamic field and chemical field under different mining schemes.(4)In order to ensure the sustainable utilization of underground fresh water resources and the benign cycle of ecological environment as the premise,in order to develop underground fresh water resources,four kinds of prediction schemes have been designed,and the simulation and prediction of groundwater dynamic field and chemical field under different schemes are carried out.The results show that,on the premise of guaranteeing the water use of industry and agriculture,the ecological environment is not destroyed and the high sulphate does not invade the fresh water area,on the basis of the 100 thousand m3/d exploitation of the current situation of the alluvial alluvial fan in the Giz River,600 thousand m3/d of the alluvial alluvial fan,200 thousand m3/d in the Kuran River alluvial fan and 100 thousand m3/d in the ATU area can be added.The amount of production can provide high quality water resources for the rapid development of social and economic development in Kashgar Delta. |
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