Safety Evaluation Of Groundwater Sources Under The Impact Of Water Conservancy Project Construction In Songyuan City

Songyuan City has serious soil salinization,less precipitation and fragile ecosystem.In recent years,the construction of river-lake connectivity project and Songyuan irrigation district project has been carried out to improve the regional ecological environment.However,the development of water conservancy projects has caused certain pollution to the groundwater in the region.For example,the infiltration of irrigation backwater pollutes groundwater quality,posing a threat to the safety of groundwater sources.Therefore,it is necessary for us to understand the safety of the groundwater source in Songyuan.This paper first studies the land use change and the change of groundwater source water quality after the development of water conservancy projects.Then,using SPSS software mathematical statistics method,Schoeller graphic method and Piper triangle graphic method,ion proportional coefficient method and Gibbs graph method,the water chemistry characteristics of the water source area in the two periods after the construction of water conservancy project are compared and analyzed.The background value of groundwater environment in the study area was calculated by mathematical statistics analysis,and the groundwater pollution assessment of the water source was carried out by using the extreme value comprehensive pollution index method.Finally,based on the actual situation of groundwater source in the study area and the local ecological environment,an index system suitable for comprehensive safety evaluation of groundwater source in the study area was constructed,and a comprehensive safety evaluation model of groundwater source was established.Comprehensive groundwater safety assessments were carried out on 10groundwater sources.The research results obtained in the thesis are as follows:1.Through comparative analysis of land use in Songyuan City in 2010 and 2018,the area of paddy fields in the area increased by 19,000 hectares;the area of grassland increased by 10,000 hectares;The area of dry land and saline-alkali land decreased,the area of dry land decreased from 1.23 million hectares to 1.227 million hectares,and the area of saline-alkali land decreased from 277,000 hectares to 251,000 hectares after the construction of water conservancy projects.2.The water quality data of the water source sites were evaluated by the fuzzy mathematics comprehensive evaluation method using the water quality data of the water source water samples after the construction of the water conservancy project.In2010,Class I water,Class II water and Class III water accounted for 80%of the total.The Class IV water and V water accounted for 20%of the total.In 2017,Class I.Water,Class II water and Class III water accounted for 72.5%of the total,and Type IV water and Class V water accounted for 27.5%of the total in the water samples of groundwater water source.3.The water quality of the water source in 2017 is slightly worse than that in2010.The reason may be that the residues in pesticides and fertilizers in the agricultural activities in some areas after the construction of the water conservancy project will infiltrate into the groundwater with the return of irrigation.The water quality is getting worse.4.The mathematical background analysis method was used to calculate the background value of groundwater environment,and combined with the extreme value comprehensive pollution index method to evaluate the pollution of groundwater in the water source.In 2017,the comprehensive pollution assessment results of groundwater sampling points in the water source area of the study area included 13 water samples from Class III?moderate pollution?to Class V?severe pollution?,accounting for 32.5%of the total,uncontaminated and slightly polluted.There are 27 water samples,accounting for 67.5%.5.Based on the index system of comprehensive evaluation of groundwater source safety and the comprehensive evaluation model of groundwater source safety,this paper conducts a comprehensive safety evaluation of 10 major groundwater sources in the study area.The comprehensive safety index E of the water source No.9is 1.67,and the safety evaluation result is relatively safe.The comprehensive safety index E of the water sources of No.1,No.2,No.6,No.7,No.8 and No.10 is between2-3.,the safety evaluation results are basic safety.The comprehensive safety index E of the water source of No.3,No.4 and No.5 is greater than 3,and the safety evaluation results are all less safe.There are fewer petrochemical enterprises in Fuyu County where the water source of No.9 Fuyu Water Supply Company is located,the pollution degree to groundwater is small,the environmental condition of the water source is good,and the water quality safety evaluation result is better.No.3 Fuyu Oil Production Plant Water Source,No.4 Xinmin Oil Production Plant Water Source and No.5 Xinmu Oil Production Plant Water Source.These three water sources are located in Ningjiang District,and there are many petrochemical enterprises nearby.The main water use applications are industrial.Water,water source groundwater quality is poor,NH₄⁺,NO₃^-,Fe and F^-content in groundwater is large,and the results of water quality safety evaluation are poor.