Study On Groundwater Occurrence And Chemical Characteristics Of Alluvial Fans In Anyang,Henan Province

The Anyang alluvial-diluvial fan aquifers is located in the northern part of Henan Province.The groundwater is the main source of domestic water and industrial water.With the acceleration of the pace of economic development,the scale of groundwater exploitation by local important enterprises has been continuously enhanced,and the groundwater flow system in local areas has been continuously changed.Analyzing the groundwater occurrence environment and the mechanism of water chemical evolution in detail can contribute to studying the connection between groundwater and the environment,and it also provides an important data reference for the rational use of groundwater resources.Based on the analysis of aquifer lithology,groundwater burial conditions,groundwater recharge conditions,groundwater flow field morphology and other hydrogeological conditions,the local aquifers are divided into shallow aquifers and deep aquifers.According to the distribution characteristics and combination relationship of the aquifers,the study area is divided into three groundwater flow subsystems.The different subsystems correspond to different cones of depression.There are a large number of industrial and mining enterprises in the western and central regions.Due to the massive pumping of groundwater,the range of groundwater depression cones expands continuously and the conditions of groundwater recharge keeps changing in local areas.The depression cone in the east has a certain connection with topographical conditions and agricultural production.According to the hydrochemical indexes(Ca2+,Mg2+,Na+,K+,Cl',SO42',HCO3-,NO3-and TDS)data of 91 water quality sampling points in the area,the characteristics of shallow and deep groundwater were analyzed and compared in the study area.The distribution of all indicators on the whole has a certain relationship with the distribution of the falling funnel.The K+,NO3-and Cl-indicators are also affected by other factors,including industrial and mining sewage,agricultural development and domestic sewage.Among the shallow aquifers,the water chemistry types are mainly bicarbonate,sulphate-calcium and bicarbonate,sulphate-calcium-magnesium,mainly distributed in the central and western parts of the study area,and the water chemistry types are diversified in the eastern region.Among the deep aquifers,the western region is dominated by bicarbonate and sulphate-calcium,and the eastern region is dominated by bicarbonate-sodium water,and other water chemistry types appear locally.On the basis of water sample test data,the apparent background value and abnormal range of each index are calculated by cumulative frequency curve and normality test method,and the abnormal range of the index is delineated,which plays a certain guiding role in identifying the cause of the abnormal index.The chemical evolution mechanism of groundwater was analyzed by correlation analysis,factor analysis,hydrochemical diagram and ion ratio characteristic coefficient method.It is concluded that in the deep and shallow aquifers,the water chemical components are controlled by the weathering and dissolution of rocks.Other factors have a certain impact on the chemical evolution of groundwater,including atmospheric precipitation and surface water infiltration replenishment,agricultural development,weathering dissolution of aqueous media,alternating cation adsorption,and sewage disposal by industrial and mining enterprises.