The Groundwater Chemical Characteristics In Ping’an Basin In East Qinghai Province

The urban agglomeration in the eastern part of Qinghai province is the most active area of human economy and engineering activities in Qinghai province.It is also the key area for the sustainable development of industry,agriculture and economy in the province.In recent years,with the rapid development of industry and agriculture and urbanization,the contradiction of water supply and demand have become increasingly prominent,groundwater quality deterioration is becoming more and more serious,has become the primary task for the rational development of groundwater resources and groundwater environmental protection.This paper takes groundwater upstream and northern mountainous hilly Huangshui River Basin in the eastern part of Qinghai County as the research object,using the Shug Kalev classification method,Piper three line diagram and related statistical analysis and a more detailed analysis of hydrochemical characteristics of groundwater in the study area;the use of single index method and fuzzy comprehensive evaluation method of groundwater quality evaluation.The fuzzy comprehensive evaluation method are constructed of trapezoidal distribution function and parabolic distribution function to evaluate the water quality and water quality conditions,draw the following conclusions:（1）The study area there are 10 main types of groundwater chemistry,according to the main anion combination of bicarbonate,carbonate,sulfate sulfuric acid,sulfuric acid,chloride sulfate bicarbonate chloride five types,of which the valley areas are mainly sulfuric acid,sulfuric acid,sulfuric acid,chloride bicarbonate chloride,mainly in hilly area of bicarbonate,chloride sulfate,mainly in Rocky Mountains bicarbonate,sulfate and bicarbonate sulfate bicarbonate chloride.（2）The study area groundwater chemical types zonation in the level,the main characteristic is the Huangshui River as the center,from mountain area to the water chemistry type valley area by HCO₃-Ca-Mg,HCO₃-Ca-Na water,gradually changed to HCO3-SO4-Ca-Na,SO4-HCO3-CL-Na,to become the bottom of Huangshui River SO4-HCO₃-CL-Ca-Mg,Cl-SO₄-Na water.（3）The main reason of groundwater chemical types in the area changed from the mountain to the valley area is gradually lengthened,the groundwater runoff way;two,the terrain gradually slowed down;three,the majority of runoff after third sand mudstone formation large;four,evaporation increases gradually,the gradual loss of water.These four factors are from the mountains to the Huangshui River Valley groundwater quality deterioration,mainly due to salinity increasing,and the change of runoff runoff route length,third strata in is the dominant factor of water quality change.（4）Compared with the single index method,the fuzzy comprehensive evaluation method is more suitable for the evaluation of groundwater quality in the study area.At the same time,the results of the two subordinate functions show the consistency of the fuzzy comprehensive evaluation method.The study area of class I and II water are mainly distributed in the bedrock fissure water,class III water is mainly distributed in the bedrock fissure water and clastic pore water,IV water mainly distributed in clastic rock pore water,after the water is distributed mainly in the unconsolidated rock pore water and pore water in clastic rocks.