| Karst groundwater is the main source of water for production and living in Dejiang County,Guizhou Province.Since the "13th Five-Year Plan",Dejiang County as the northeastern Guizhou to connect Chongqing,Hunan,Hubei transport hub and regional central city,in the transportation,tourism and other aspects of the development of a good opportunity,many projects in the construction of karst groundwater resources,the contradiction between supply and demand has become increasingly prominent,the continuous increase of groundwater production,hydrodynamic characteristics,water chemistry characteristics of karst groundwater system will be affected,resulting in the region's water supply security and economic development by Threaten.Therefore,indepth analysis of local karst groundwater storage conditions,hydrodynamic characteristics,research and control of local karst groundwater hydrogeochemical characteristics of the main geochemical mechanism and karst water in the main source of cations,to help people understand the underground water chemical environment of renewable Ability,scientific and effective management,protection and rational development and utilization of water resources has a very important significance.Based on the basic geological conditions,hydrogeological conditions and regional tectonic characteristics of the study area,this paper analyzes the karst groundwater in the study area by using the theoretical method such as hydrogeology and hydrogeochemistry,and so on.The spatial distribution characteristics and formation mechanism of water chemical composition were studied,and the formation and evolution of chemical composition of karst groundwater were studied by hydrological geochemical reverse simulation.Specific conclusions and conclusions:(1)The karst groundwater in the study area is divided into four types: HCO3·SO4-Ca type water,HCO3-Ca type water,HCO3·SO4-Ca·Mg type water and SO4-Ca type water by Shukallev classification and Piper three line,Which is mainly HCO3·SO4-Ca type water.Combined with the lithological characteristics of the study area,the chemical composition of karst groundwater is mainly controlled by the dissolution of minerals such as carbonate rock and gypsum.(2)By comparing the spatial distribution of TDS,Ca2+,Mg2+,HCO3-,SO42-in the groundwater,it is concluded that the distribution of Ca2+ and HCO3-is consistent with the distribution of TDS,which is increasing from recharge area in the middle of the study area to excretion area.The distribution of Mg2+ is similar to that of SO42-,and their high anomalies are concentrated in the karst groundwater of Xiangshui Dong and Qingtangtou excretion area.Indicating that the groundwater in the runoff process calcite,gypsum and dolomite and other minerals continue to dissolve,so that the study area four kinds of major ion content has increased to varying degrees.(3)Based on the correlation analysis,ion scale coefficient analysis and cluster analysis of chemical components of karst groundwater in the study area,showed that TDS was highly correlated with total hardness and Ca2+,and Cl-and Na+(K+ and Na+ were combined)Very weak correlation.The dissolved amount of karst groundwater in the study area is larger than that on the gypsum.The dissolution of the gypsum is greater than that of the dolomite,that is,the dissolution of the carbonate rocks is mainly in the study area.Filtering followed.(4)The water quality evaluation of groundwater in the study area was carried out by using the pairwise analysis method based on entropy weight.The results showed that the groundwater quality of the study area was good,and the water of the class I was 55.3% of the total water and 36.8% of the class II water.Only individual water samples for the evaluation of class III water,suitable for people to drink.(5)The calculation results of the mineral saturation indices of the water samples at the four simulated paths in the study area show that,except that the partial water samples have the characteristic of becoming saturated with calcite,The remaining water samples are in the unsaturated phase of the mineral phase,the mineral has continued to dissolve into the groundwater solution trend.The results of water-rock interaction show that the formation of chemical composition of groundwater in the study area is: the effect of dissolving,cationic adsorption,mixing,precipitation and deprivation.The dissolution of calcite,dolomite and gypsum occurred in the northern area of the study area.However,due to the lithology,topography and other factors,the complexity of the water-rock interaction occurred on different water paths is different The The water-rock formation in the southern area of the study area is the precipitation of calcite,gypsum and dolomite. |
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