| Alluvial-diluvial fan in the north of Xinxiang city is located in the north of Henan province,south of Taihang mountain.With the development of local industrial and mining enterprises and the improvement of agricultural production activities,the exploitation amount of groundwater resources is gradually increased,which changes the groundwater occurrence state and hydrodynamic flow field in local areas.Due to the influence of farmland irrigation,industrial and mining enterprises and residential wastewater,local groundwater environment has also changed.This paper focuses on the analysis of groundwater distribution characteristics,hydrochemical characteristics,influencing factors and hydrochemical evolution mechanism,so as to provide a theoretical basis for the local scientific and rational exploitation and utilization of groundwater resources and to ensure safe agricultural production.This paper analyzes the spatial distribution characteristics,burial conditions,flow field shape and other factors of the aquifer in the study area,and divides the aquifer into shallow aquifer and medium-deep aquifer from the spatial basis through theoretical basis;At the same time,the dynamic changes of shallow groundwater and mid-deep groundwater are analyzed,which are mainly divided into five types:meteorological?mining type,meteorological and hydrology?mining type,meteorological and runoff?mining type.The potential pollution sources of the aquifer in the study area are mainly industrial pollution sources,agricultural and animal husbandry pollution sources and domestic pollution sources,of which industrial and mining enterprises pollution sources have the greatest impact on groundwater hydrochemistry.Due to the large-scale exploitation of groundwater,a landing funnel has appeared in some areas,which has changed the natural environment of groundwater.Sampling points according to the 112 groups of groundwater hydrochemical index(TH,TDS,Ca2+,Mg2+,Na+,K+,Cl-,SO42-,HCO3-and NO3-)analysis of test results,this paper analyzes the shallow groundwater and deep groundwater in the water chemistry index distribution,hydrochemical index distribution affected by hydrodynamic field,surface water and the influence of natural factors such as rainfall,also including industrial and mining enterprises waste water,farmland irrigation and human factors such as residents living waste water.The water chemistry types of shallow groundwater are mainly bicarbonate and bicarbonate-sulfuric acid type water,accounting for about 76.8%of the total sample,but the water chemical types are complex and diversified along Weihe river and Huixian area in the south of the study area.The water chemistry types of the mid-deep groundwater are also mainly bicarbonate and bicarbonate-sulfuric acid type water,accounting for about 86.7%of the total samples,and sulfuric acid and sulfuric acid chlorine water appear in some areas along the Weihe river.The hydrochemical types are relatively simple.Through correlation analysis,principal component analysis,water chemistry,ion ratio coefficient method and graphical method,etc,to analyze groundwater formation mechanism,known in the shallow and deep groundwater water chemical composition are controlled by rock weathering,and atmospheric precipitation,surface water quality,water medium,Alternating cation adsorption,industrial and mining enterprises,sewage,agricultural production-life waste water all have effect on water chemistry.The distribution rules of hydrochemical types in different periods in the study area were analyzed.Based on the water quality data of the three typical monitoring wells during the dry and abundant periods,the analysis of the groundwater evolution mechanism of the alluvial fan was carried out.The type of water chemistry from the top of the fan to the middle of the fan gradually becomes more complex,and the content of water chemistry indicators gradually increases,but it also fluctuates due to external factors. |
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