Temporal And Spatial Evolution Analysis Of Brackish Water In Guantao County

Due to large-scale overexploitation of shallow groundwater,the water level in Guantao County has dropped seriously,forming multiple funnel areas,which has a great negative impact on people’s lives.In recent years,the development and utilization of brackish water has attracted wide attention.Because of the wide distribution of brackish water resources in Guantao County,and generally shallow burial depth.Therefore,how to accurately build a numerical model of brackish water dynamics to simulate the distribution of brackish water in the region,combined with the prediction of the prospects of brackish water in the scientific exploitation scheme,has an important guiding significance for the rational control and development and utilization of water resources.In this thesis,based on the historical hydrogeological data of Guantao County and the latest borehole histogram,the hydrogeological parameter zoning and top and floor elevation of brackish water are determined.Then,based on the actual situation of the study area,the groundwater boundary conditions and source sink terms are simulated.Combining the properties of brackish water in Guantao County,GMS software is selected to establish a heterogeneous,isotropic,two-dimensional,unstable flow model,and the model accuracy is verified with the actual observation well data.Secondly,the period from January 1,2017 to December 31,2017 is selected as the identification period of parameters.By adjusting the permeability coefficient and yield to fit the simulated water level with the actual observed water level,the model identification results show that the absolute average residual is 0.356 m,the maximum residual is0.589 m,the minimum residual is-0.01 m,and the standard root mean square is 4.875%;The parameter validation period is from January 1,2018 to December 31,2018.That is,the parameter partitions and identified parameters of the model will not be modified.The source sink item data of 2018 will be imported into the model.The model validation results show that the absolute average residual is 0.334 m,the maximum residual is0.674 m,the minimum residual is-0.012 m,the standard root mean square is 4.891%,and the deviation is within the 95% confidence interval.The results show that the established model can accurately simulate the hydrogeological situation and the change of brackish water level in the study area.Finally,the numerical model was used to predict the change of brackish water level in Guantao County from 2020 to 2029,and the temporal and spatial evolution of brackish water in Guantao County from 2020 to 2029 was analyzed from the perspective of time and space.From 2017 to 2020,on the basis of the obvious decline of the brackish water level in the study area,the low value area of the brackish water burial depth in the study area will shift from Shoushansi Township and Fangzhai Town to Guantao Town and Nanxu Village,indicating that the exploitation of brackish water in the whole study area is increasing.From 2020 to 2024,on the basis of slowing down the declining trend of brackish water level,the low value area of brackish water level burial depth will continue to move to the northeast,indicating that the exploitation of brackish water in the whole study area has decreased but is not obvious.From 2024 to 2029,the brackish water level in the study area has not changed significantly,and the brackish water system in the whole study area is in a state of balance between supply and discharge.