Groundwater Resources Evaluation Of The Yueyahu Area In Yinchuan Of Ningxia

To seize the strategic opportunity to accelerate the development of Ningxia,Autonomous region proposed the strategic thinking that“Gradually extending the whole of Yinchuan city in the direction of Yellow River and construction of riverside district on the east side of the Yellow river.”But water scarcity becomes the important factors restricting economic development,in order to solve the water resources crisis,the government plans to build some city reserve groundwater resources areas on the east side of the Yellow river.This study is based on the full collection,analysis and study of previous work,and through the method of field work and laboratory analysis,etc.to identify the hydrogeological characteristics.Analytical and numerical methods are adopted to evaluate groundwater resources,establish the water source of water supply and solve the problem of water consumption for the construction and economic development of the riverside district.Through the preliminary investigation,we found that:there are some differences between the previous understanding of the hydrogeological conditions of Yueyahu area.Predecessors thought the quaternary in this area was thin in thickness,small in water yield and water quality is poor.But this survey find that the maximum thickness of Quaternary in Yueyahu area is greater than 250m which is characteristics of multilayer structure,and in depth of 20-40m distribute a continuous layer of cohesive soil,above the layer is divided into the firstⅠwater-bearing formation which is characteristics of small water and complex quality;below the layer is divided into the firstⅡwater-bearing formation which is characteristics of great thickness,great quantity and good quality.Therefore,we carry out hydrogeological exploration in Yueyahu area which is located in the east of the Yellow River,predict the changes of water level under mining conditions,evaluate groundwater resources,investigate and build water supply sources.The results show that:the firstⅡwater-bearing formation in yueyahu area has a big aquifer thickness,the average thickness is 56.63m,with good water abundance and in most of the area the specific water yield of a single well is greater than 1000m~3/d,the content of total dissolved solids is less than 1g/L,which have the conditions to set up groundwater source.Design of 10 production wells with single well exploitation of 1000 m~3/d and well group production of 1×10~4m~3/d.By interfering superposition analytic method to predict water under mining condition in 20 years evaluation period,the maximum drawdown of groundwater level is 45.498m,which has not exceed the buried depth of the roof of firstⅡwater-bearing formation,and indicate that the exploitation of 1×10~4m~3/d won’t produce any environmental geological problems.Analytical and numerical methods are adopted to evaluate groundwater resource,the results show that under the mining condition the maximum recharge obtained by the objective layer is 1.74×10~4m~3/d,which indicate that the pumping of 1×10~4m~3/d of the water source is guaranteed.By water quality evaluation,the groundwater quality is good,in addition to fluoride generally exceeded,individual hole with different degree of sulfate,nitrate and nitrite overweight,the rest all meet the drinking water sanitary standard.By the hybrid of the solute we can predict that the content of the total dissolved solids of groundwater is 0.782mg/l after exploitation of 20 years.Through the research work we set up a centralized water supply source with quantity of 1×10~4m~3/d,which provides a source of water supply for the construction and economic development of riverside district and provide a basis for government decision-making.