Research On Hydrochemical Characteristics And Controlling Factors Of Shallow Groundwater In The Source Region Of The Zihe River

The shallow karst groundwater in the source area of the Zihe River is an important supply source for industrial and agricultural and residential water use in Boshan District,Zibo City.It plays an important supporting role in ensuring the drinking water safety,ecological environment balance,rapid economic development and overall social progress of urban and rural residents.In recent years,due to the decrease of rainfall and the massive exploitation of groundwater resources,the water level of karst groundwater has dropped drastically.The contradiction between supply and demand of water resources in the region has become more and more serious.The impact of human activities on groundwater karst water system is also increasingly obvious,which seriously threatens the sustainability of regional water resources.In order to alleviate the shortage of industrial and agricultural water in Boshan District,Zibo City,the local government plans to build a karst groundwater source above Xiejiadian Village in the Zihe source area.China University of Mining and Technology cooperated with Zibo Branch of Shandong Provincial Geology and Mineral Engineering Investigation Institute to carry out research work on water source survey and water source protection area division.On this basis,the author had carried out a supplementary field exploration and geological background survey of the Zihe source area and had collected the conventional ion data(⁺?(6⁺?(6²⁺?2)²⁺?7)^-?₄^2-?₃^-?₃^2-?₃^-)of the groundwater samples of the main aquifer?Quaternary aquifer,fissure aquifer,karst aquifer?.The Shukalev classification and the anion-cation classification method were used to classify the groundwater chemical type in the working area.The contour analysis of the main components in the region was further drawn by the Kriging interpolation analysis method of ArcGIS software.The main ion composition and spatial variation of the region were qualitatively analyzed.Based on the qualitative analysis and the geological background data,the regional groundwater flow path and the possible mineral phases in the aquifer were determined.The scientific and rational hydrogeochemical model was established by using PHREEQC software,and the chemical evolution process in the groundwater flow path of the study area was quantitatively simulated,and the intensity and evolution characteristics of groundwater geochemistry were further revealed.Finally,from the perspectives of natural factors and human factors,the multi-disciplinary method was combined with the analysis data that has been mastered to analyze the control factors of groundwater chemical characteristics in the study area.Research indicates:?1?The cations in the three aquifers in the water source protection area of Xiejiadian are mainly(6²⁺and2)²⁺,and the anions are mainly₃^-and₄^2-.All water quality is in line with Class III water standards.(6²⁺,2)²⁺,₃^-concentration are relatively stable in the aquifer;?6⁺?⁺?₃^-?7?^-has a large variation in groundwater concentration in the study area,which is more affected by environmental factors.?2?The large-scale exploitation of groundwater in the study area has caused the temporary hardness of groundwater in some areas to increase;the(6⁺concentration gradient is roughly inversely proportional to the direction of water flow,indicates that the content of rock salt and thenardite in the aquifer is very small.From the larger mean value and standard deviation and the regular distribution characteristics of₃^-show that the absolute value of groundwater is larger,the relative content is not much different,and it is less affected by external factors.The leaching and filtration effect in the study area is relatively strong,combined with the distribution characteristics of TDS,it is judged that the overall water quality of the study area is less affected by external factors.Rainfall and man-made pollution do not have much impact on groundwater.?3?Hydrogeochemical quantitative simulation reveals that de-doping is the main water-rock interaction of Quaternary loose pore aquifer.The variation of main ion concentration in the simulated path of massive rock weathering fissure water aquifer is consistent with the hydrogeochemical characteristics of the recharge zone.The dissolution and precipitation of sulfate and carbonate and the alternating adsorption of cations are the main hydrogeochemical effects.The carbonate rock karst fractured water-bearing rock group has deep burial,and has the characteristics of single water chemical type,stable water chemical characteristics and strong water-rich characteristics.The hydrogeochemical action is mainly based on the dissolution and precipitation of sulfate and carbonate and the alternating adsorption of cations,but the intensity is small.The variation of the main ion concentration in the simulated path is consistent with the hydrogeochemical characteristics of the discharge area.?4?The velocity of the weathered fissure aquifer is faster,and the flow rate of the Quaternary aquifer and the fractured karst aquifer is slow.In general,the water-rock interaction is the main controlling factor for the groundwater flow field,and the chemical evolution of groundwater in the source region of the Zihe River.The geological and hydrogeological conditions control the groundwater flow field,which in turn affects the strength of the water-rock interaction.The chemical characteristics of groundwater are affected by the planting industry in some areas,and Human activities have also become an important factor in the Yinjiayu area in the middle of the reserve.The research of the thesis will help the local government and relevant departments to master the distribution law of karst groundwater and enrich the research results of karst groundwater chemistry in the Zihe area.At the same time,it also rationally develops and utilizes water resources for the source area of the Zihe River,better prepares and protects the groundwater source,eases the contradiction between water supply and demand in the region and controls the decline of groundwater,provide a scientific basis for preventing regional groundwater pollution,improve groundwater resource management and rationally develop and protect karst groundwater resources.