The Assessment And Reasonable Development Of Groundwater Resources In River Valley Plain Of Lhasa City

River Valley Plain of Lhasa City is one of the most densely populated and the fastest-growing economy areas in the Tibet autonomous region,which is a plateau Valley landforms, low of hydrological geological research level, lack of systematic evaluation and research on groundwater resources. Based on the evaluation and analysis of groundwater resources in Lhasa river valley plain,this paper aims to provide scientific basis for the rational exploitation and utilization of groundwater resources.Based on systematic analysis of geological and hydrogeological conditions, we established a hydrogeological conceptual model in the river valley plain of Lhasa City, and based on the GMS software to establish the numerical model of groundwater flow, and the model is identified and validated with good results. Using the water equilibrium method and numerical method to calculate?analyse and compare groundwater equilibrium, get the reasonable calculation results: groundwater allowable withdrawal were 345222.21m3/d and 303687.40m3/d, and groundwater exploitation potential index were 0.96 and 0.97. The comprehensive evaluation of groundwater quality shows that the groundwater quality in the study area is excellent, and the water quality is poor in some areas.The dynamic change of groundwater in river valley plain of Lhasa City is the overall decline of groundwater level, and shows a certain stage, but the overall trend of groundwater flow has not changed. Using the groundwater flow numerical model to calculate and analyse the 1970, 2000 and 2015 groundwater equilibrium, comparing results show that: the groundwater equilibrium gradually from positive equilibrium to negative equilibrium and the Lhasa River plays an important role in water balance; The main reasons for the impact of human activities on Groundwater is the increasing mining of groundwater year by year, the urban construction land has increased and the wetland area decreased. Using groundwater flow mode to forecast the changes of water level of different mining schemes, show that:in the current mining layout condition has little effect on the groundwater level but should not exceed the current exploitation's 1/2; In the case of increasing the amount of exploitation, building new water source area along the Lhasa river is the best mining scheme. After comprehensive analysis, this paper puts forward some measures for rational exploitation and utilization of groundwater resources in River Valley Plain of Lhasa City.