Dynamic Characteristics Of Hydrogeology With Water Supplement In Kunty Mine,Qaidam Basin

Kunty salt lake located in Qaidam basin,it was a comprehensive salt mineral mine which mainly produced liquid minerals.Water supplying project was carry out from July 2013 in order to improve the economic benefits of salt lake exploition.Ascertaining the dynamic characteristics of aquifer permeability,hydro-chemistry and water level in the mine with the water supplement had great significance in evaluate the effect of water supplement and reasonable plan the exploition of salt lake.This research used the methods of computer iteration,software,manual calculation and conventional ions test to calculate and analyze the data of pumping test and long-term observational network.We used the analysis result to ascertain the dynamic characteristics of the aquifer permeability and used the water level and ions concentration contour map to explain the changing discipline of water level and ions concentration in unconfined aquifer.We also combined the analysis data of water level and hydrochemistry to evaluate the effect of water supplement.The specific conclusions are as follows:1.The unconfined aquifer in Kunty salt lake had the space and time variability.In the edge of the mine,the permeability of unconfined aquifer which was not affected by pumping was very poor.The permeability coefficient of the aquifer was 0.28 m/d-0.59 m/d and presented feeble fluctuant tendency as time goes on.In the middle of the mine,the permeability of unconfined aquifer which was not affected by water supplying was very poor.The permeability coefficient of the aquifer was 0.52 m/d-5.81 m/d and presented fluctuant tendency as time goes on.In the middle of the Sedimentary center area of mine,the permeability of unconfined aquifer which was affected by water supplying and pumping was very good.The permeability coefficient of the aquifer was 78.65 m/d-376.33 m/d.affected by the main minerals’ solid-liquid transformation in unconfined aquifer,the permeability showed obviously fluctuating change.Due to unique lithology characteristics and wasn’t affected by the water supplying and pumping,the confined aquifer had a very poor permeability which remained relatively stable.The calculating result of permeability coefficient was 0.14 IV m/d-0.36 m/d.2.The water levels of unconfined aquifer showed a high level in north and east in the mine.The unconfined brine mainly flowed from northeast to the drawdown funnel.The unconfined water level in drawdown funnel showed a continuous decline and others remained relatively stable.The water dissolved the soluble salts which made the mud and clay redeposit in suit was the efficient reason that caused water level showed abnormal distribution on canal and both side area.3.With the water supplying and pumping,the whole concentration of K⁺、Mg²⁺ in unconfined brine had no significant change and it was relatively low in the north of the mine.In the middle and south,concentration of K⁺、Mg²⁺ in unconfined brine was relatively high.The water dissolved the carnallite and other soluble salt which contained potassium and magnesium in the process of runoff made the concentration of K⁺、Mg²⁺ show a obviously rising trend on the direction of the flow of the unconfined brine.4.The water dissolved the halite in the process of runoff made the brine have a high concentration of Na⁺ and Cl^-.With the dissolution of carnallite,epsomite and loeweite,the concentration of K⁺ and Mg²⁺ in the brine increased gradually made the Na⁺ and Cl^-dissolve out in the form of Na Cl solid caused the concentration of Na⁺ and Cl^-showed a declining trend on the direction of the flow of the unconfined brine.5.The dissolution of glauber’s salt provided most of the SO₄^2- and sectional Na⁺ of the brine.Because the solubility was affected by the temperature of water,the whole concentration of SO₄^2- and Na⁺ in unconfined brine both showed a increased after an initial decrease tendency between May and November 2015.The water dissolved the glauber ’s salt in the process of runoff made the concentration of SO₄^2- gradually increased on the direction of the flow of the unconfined brine.6.The unconfined brine in Kunty mine was in negative balance.In order to make sure the salt lake could be sustainable exploited,adding the supplying water volume would be advised to make the volume of unconfined brine be in balance.The supplied water dissolved soluble sylvite in the process of runoff could not only promote the concentration of K⁺,but also enlarge the pore channel.In order to promote the quantity of the unconfined brine,enlarging the distance between canal and cone of depression would advised to make the water dissolved more soluble sylvite in the process of runoff.