Dynamic Analysis Of Groundwater In A Plain Area And Zoning Prediction Of Water Quality At Different Scales

Groundwater,as an indispensable part of the water resource circulation process,plays an extremely important role in human survival and development.The important significance of dynamic analysis and prediction of groundwater level and water quality is that it can better protect and use groundwater resources.This article uses hydrogeological survey,field sampling,experimental test analysis,mathematical model calculation and other methods to analyze and predict groundwater dynamics in the study area.First analyze the natural geographical conditions,geological conditions,hydrogeological conditions of the study area,and then use mathematical models(gray system model,linear regression model,neural network NAR model,sequence ARIMA model)for calculation and analysis,predict the groundwater level and water quality of the study area Distribution laws and development trends,and the classification and evaluation of groundwater quality in the study area to provide support for the protection of groundwater resources in the study area.The article has achieved the following main results:(1)The characteristics of groundwater level dynamic changes in the study area were analyzed,and the groundwater level changes of the first aquifer,the second aquifer,the third aquifer,and the fourth aquifer in the study area were drawn,and the years of each aquifer were obtained.The lowest water level is from February to March,and the annual highest water level is from June to August,and the change in water level during the year is mostly 2-6m;(2)Analyzed the status quo of groundwater quality in the study area and the distribution and dynamic characteristics of over-standard indicators in different aquifers,combined with the hydrogeological conditions in the study area,the total hardness,total dissolved solids,ammonia nitrogen and Single index water quality zoning chart of nitrate nitrogen.Among the monitored indicators,the detection rate of indicators such as total hardness,total dissolved solids,chloride,sulfate and permanganate is extremely high,and the detection rate is 100% or close to 100%;overall detection from the plain area In view of the situation,in addition to the low detection rate of volatile phenols in general chemical indicators,the detection rate of other indicators is greater than 60%,of which the detection rate of aluminum and ferrous iron exceeds 80%;the detection rate of toxicological indicators The larger one is fluoride,and the detection rate is close to 100%;the second is nitrate,and the detection rate is 90%;the detection rate of arsenic and nitrite is also higher,about 60%,and the other indicators are less than 10%.The over-standard points of ammonia nitrogen,nitrite nitrogen,nitrate nitrogen and fluoride mainly appear in the first and second aquifer groups.Compared with the two aquifer groups,the over-standard rate of the second aquifer is significantly lower than that of the first aquifer Layer group;the indexes of the third aquifer group whose content exceeds the standard rate is more than 5% are ammonia nitrogen,manganese,total hardness and nitrite nitrogen,and the fourth aquifer group of ground water exceeds the standard rate of 5% indicators are ammonia nitrogen,manganese,nitrite Salt nitrogen and fluoride.(3)Analyze the distribution and dynamic variation characteristics of groundwater comprehensive water quality in different aquifers in the study area,draw the comprehensive index water quality zones of the first aquifer,second aquifer,third aquifer and fourth aquifer in the study area And the change curve graph,it is concluded that the area of the comprehensive index exceeding the standard of the first aquifer in the high water period of 2017 has expanded by 259km2 compared with the same period of 2011.Compared with the same period in 2011,it has expanded by 71km2;the area of the third aquifer's index exceeding the standard has changed less,and the high water period in 2017 has increased by 33km2 compared with the same period in 2011.(4)Four different mathematical models of gray system model,linear regression model,neural network NAR model,and time series ARIMA model were used for calculation,and the dynamic changes of groundwater level and water quality in the study area were predicted.Advantages and disadvantages and applicability,it is concluded that the ARIMA model has higher prediction accuracy;(5)The time series ARIMA model was used to predict the groundwater quality changes at the regional and urban scales of the second aquifer,and the predicted concentration distribution maps of the urban and regional scales of the second aquifer were drawn based on the prediction results of different durations.It is concluded that the area of the predicted concentration of nitrate in the second aquifer at the regional and urban scales exceeds the standard area,and the predicted concentration and the area of the index increase with time.