Groundwater Resources Evaluation Under The Eco-environmental Restriction In The Golmud River Basin

Golmud river basin is located in the south of the Qaidam Basin which is part of the arid region in northwest China,and the area has small rainfall and large evaporation.The typical alluvial fan deposits thick sand and gravel and receives a large amount of river water recharge,which is a good groundwater storage site and have abundant groundwater.The development and utilization of groundwater in the study area is lower,so it has great potential for exploitation.Golmud City is located in the Golmud River alluvial fan and is the central city of Qaidam Basin.With the development of urban groundwater demand will gradually increase.Groundwater is not noly an important source of water supply but also the safeguard water of the vulnerable eco-environment in arid region and previous groundwater resources evaluation research work lack of considering the ecological environmental impact,the evaluation results is unreliable,therefore,evaluating of groundwater resources in watershed under ecological constraints and calculating the area of groundwater resources,which is of great significance to the sustainable development of groundwater in the study area.This paper collected large amount of survey data and hydrogeologic condition and recharge runoff discharge conditions,then establish groundwater flow numerical simulation model(2011.1-2015.12)by using GMS.Groundwater budget of study area in 5 years was analyzed and the results show that the average annual groundwater recharge is 6.91×10~8m~3/a,the average annual excretion is 6.75× 10~8m~3/a.On the basis of thorough analysis of the hydrogeological conditions,water planning and ecological environment constraints,we propose five schemes to evaluate groundwater resources,the forecast period was 30 years.The simulation results indicate that amount of present water resources supply is 6.58×10~8m~3/a,groundwater exploitation mainly comes from spring discharge evaporation and groundwater storage.Comprehensive comparison of different schemes of evaporation capacity reduction,springs emissions reduction,area of vegetation suitable water level,the location of the maximum drawdown appeared and maximum depth,we recommend scheme three as the best.The maximum drawdown in the third phase water source,the maximum depth was about 16.0 m,the total amount of captured evaporation and srings emissions reduction acounted for 47.95% of the exploitation,area of vegetation suitable water level was reduced by 13.30%.Eventually,we decide groundwater exploitable quantity was 2.92 ×10~8m~3/a.This research can provide a scientific basis for the rational development and utilization of water resources and ecological environment protection.