Feasibility Study On New Groundwater Sources In Shuangcheng District Of Harbin

In recent years,the economy of Shuangcheng District has developed rapidly,the urbanization process has accelerated,and the demand for water resources has also increased.New water sources,increasing water supply,improving water supply quality,and ensuring urban water supply security have become urgent tasks,but blindly exploiting groundwater resources.Various environmental hydrogeological problems will inevitably arise,so the feasibility of new groundwater sources must be evaluated.This paper fully considers the feasibility of affecting the groundwater source,constructs a new groundwater source feasibility assessment system,and applies the feasibility evaluation system to comprehensively evaluate the feasibility of the new groundwater source in Shuangcheng District.The main results are as follows:(1)Evaluation of groundwater resources:Calculated by the equilibrium method and the mining coefficient method,the average annual groundwater resources in the region is 10492.81×10~4 m~3/a,and the groundwater recoverable resources are 8478.76×10~4m~3/a.(2)Groundwater quality assessment:The Nemero index method is used for comprehensive evaluation.The groundwater in the area is mainly Class IV or V water.The V water is mainly distributed in the south of the township,the northeast of Lequn Township,and the central part of the city.All other areas are sporadic,the majority of class IV water;some areas of Shuiquan Township have Class II and III.From the single index evaluation,the main reason for the comprehensive evaluation results of IV and V is that the iron,manganese,total hardness and TDS in the area have different levels of exceeding the standard.The super standard can reach the standard after being treated by the water purification plant and can be used as a living drink water;ammonia nitrogen,nitrate and sulfate in some areas exceed the standard,which may be affected by agricultural non-point source pollution and industrial wastewater discharge.The hydration type of groundwater in the whole area is concentrated,and the anions are mainly bicarbonate type and bicarbonate type;the cations are mainly calcium type,calcium magnesium type and calcium sodium type.(3)Analysis of water supply and demand balance:analysis of current social and economic indicators,water consumption,water supply and development trends,and forecast annual demand and annual water demand and water supply.By 2020,the demand for water in Shuangcheng City is 73,600 m~3/d.By 2030,the urban water demand will reach 92,100 m~3/d;under the premise of not adding new water supply capacity,the annual urban water supply to the near-term and long-term planning levels will be 30,000 m~3/d.According to the analysis of supply and demand balance,Shuangcheng City will have a water shortage of 43,600 m~3/d by 2020 and a water shortage of 62,100 m~3/d by 2030.Considering the 25%water loss of the water purification plant,the total water shortage in the Shuangcheng urban area in the near future(2020)is 54,500 m~3/d.(4)The construction of the feasibility evaluation system:Based on the summarization of relevant water source evaluation research at home and abroad,combined with the actual situation of the Shuangcheng District,a set of feasibility evaluation index system is constructed,which is divided into target layer,criterion layer,index layer and factor layer.The criterion layer is composed of six factors closely related to water source construction,such as water quantity,water quality,mining technical conditions,mining economic conditions and environmental impact;the indicator layer is a factor that describes the criterion layer in more detail under the control of the criterion layer.There are 14 relevant indicators including the current mining coefficient of groundwater in the water source,the future mining coefficient,the exploitable modulus,the remaining exploitable modulus,the groundwater environmental quality and the industrial water quality.The evaluation results are divided into five levels,namely,extremely feasible,feasible,feasible,basically feasible,infeasible,and extremely infeasible,and assigned the corresponding grades of I,II,III,IV,and V respectively.According to the relevant evaluation criteria and expert guidance,combined with the individual's understanding of each evaluation index,the evaluation criteria of each indicator are determined.By constructing the pairwise judgment matrix of each evaluation factor,the weight of one evaluation factor is calculated by the analytic hierarchy process.Finally,the fuzzy comprehensive evaluation method is used to evaluate the feasibility of the new groundwater source.(5)Feasibility evaluation of new groundwater source:The feasibility of the new groundwater source feasibility assessment system constructed in this paper is used to evaluate the feasibility of the proposed water source in Shuangcheng District.Firstly,the indicators of the criterion layer are evaluated separately,and the evaluation values of each factor in the index layer are determined.Then,the membership degree of the evaluation factors to the evaluation criteria is determined according to the membership function.Finally,the comprehensive evaluation vector B_c is calculated by the fuzzy comprehensive evaluation method.After comprehensively evaluating the groundwater in the newly-built water source of Shuangcheng District without being treated by the water purification plant,the maximum value in the comprehensive evaluation result vector B_c is 0.3587,and the corresponding evaluation level is IV.The evaluation conclusion is not feasible;the groundwater of the water source is purified by the water purification plant.After processing,the maximum value in the comprehensive evaluation result vector B_c is 0.5491,and the corresponding evaluation level is III,and the evaluation conclusion is basically feasible.