Analysis And Prediction Of Spatial Distribution Characteristics Of Groundwater Quality In Anhui Section Of Tan-Lu Fault Zone Based On GIS

Groundwater is an important source of water for residents'lives,and the degree of development and utilization is increasing year by year.In recent years,with the rapid development of the economy,the environmental problems of groundwater pollution have become increasingly prominent.In this paper,the shallow groundwater in the Anhui section of the Tanlu fault zone is taken as the research object.On the basis of fully collecting and sorting out the existing hydrogeological data in the study area,a field hydrogeological survey is carried out.Comprehensive analysis of the water quality data collected in this field survey and the collected groundwater quality monitoring data from 2011 to 2018,carried out quality assessment and prediction research of groundwater quality,and analyzed the spatial distribution characteristics of groundwater quality,and obtained the following main research results:?1?According to the full analysis data of groundwater quality collected by this field survey,groundwater hydrochemical statistical analysis is carried out,and the groundwater chemical type in the study area is divided based on GIS technology.The results show that the groundwater in the study area is mainly neutral-weak alkaline water with moderate or low salinity.The main cation content is Ca²⁺?Na⁺.The main anion content is HCO₃^-.The water chemistry types in the study area are mainly HCO₃-Na,HCO₃-Ca and HCO₃·Cl-Na.?2?According to the full analysis data of groundwater quality,groundwater quality evaluation was carried out by single factor evaluation method,principal component analysis method and Nemerow index method.Firstly,23 groundwater quality indicators were selected to evaluate water quality by single factor index method.The results showed that there were 13 super-class III water quality indicators in 23 water quality indicators in the study area,and the main over-standard indicators were NO₃^-,Fe and Mn;Then,Principal Component Analysis is used to determine the main factors affecting groundwater quality in the study area are Cl^-,Fe,Mn,NO₃^-,SO₄^2-,F^-;Finally,the six main factors were selected and evaluated by the Nemerow index method,and the water quality map was drawn based on the ArcGIS.The results show that,in general,the groundwater quality in the study area is mainly good and poor,and the groundwater quality in the southern part of the study area is better than that in the central and northern parts.The groundwater quality in the southern Dabie Mountains is better than that in the southern hilly plains.?3?The water quality indicators of NO₃^-,Fe and Mn in the study area from 2011 to2018 were selected as prediction indicators to establish a groundwater quality prediction model based on BP neural network.The groundwater quality of 10monitoring points was predicted and evaluated by the Nemero index method.The evaluation results show that the water quality of of some monitoring points is polluted to a certain extent;and the water quality map of Hefei area in 2011 and 2025 is mapped to analyze the spatial distribution characteristics of water quality in Hefei area.The results show that the groundwater quality of better and worse in Hefei area is reduced,while the extremely poor area is increasing.