The Analysis Of Surface Water And Groundwater Coupling Model In The Mihe River Basin On The Southern Laizhou Bay Under Changing Environment

The Mi River Basin is located in Weifang City,Shandong Province.It is an important industrial and agricultural production base in Shandong Province.The high development of water resources in this region limits the development of social economy.At present,the interaction between surface water and groundwater is a hot spot in the field of hydrology,and establishing a coupled model of surface water and groundwater is an effective means of rational allocation of water resources.This study takes the Mihe River Basin on the south bank of Laizhou Bay as the research area,and considers the impact of changing environmental factors on water resources based on the establishment of a coupled model of surface water and groundwater.In the study,SWAT(Soil and Water Assessment Tool)was used to build the Mi River Basin surface water model and GMS(Groundwater Modeling System)MODFLOW module was used to build the Mi River Basin groundwater model.Through ArcGIS,the SWAT hydrological response units(HRU)and the orthogonal grid(CELL)in MODFLOW can achieve spatial correspondence,and the groundwater recharge calculated in the output file of the SWAT surface water model is input into the MODFLOW groundwater model.Coupling of surface water and groundwater.At the same time,since human activities will have an impact on the hydrological process of the basin to a large extent,this paper further explores the impact of land use types on surface runoff and the impact of artificial mining on groundwater dynamics on the basis of the constructed model,and proposes groundwater reduction.Take advice.The main research contents and conclusions are as follows:(1)Based on the DEM data of the Mi River Basin,land use types,soil types,and climate data from the CMADS V1.2 atmospheric assimilation-driven dataset from 2008 to 2018,the SWAT surface water model of the Mi River Basin was constructed,and the SWAT-CUP software was used.Validate and validate the model.The calibration of the model used the monthly runoff data of Tanjiafang Hydrological Station from 2010 to 2013,and the validation of the model used the monthly runoff data of Tanjiafang Hydrological Station,Qingtianhu Hydrological Station and Fowu Hydrological Station from 2014 to 2018.The results show that the Nash coefficient NSE,the coefficient of determination R2 and the coefficient of deviation PBIAS in the regular and verification periods are all within a reasonable range,indicating that the simulated and measured values of monthly runoff are well fitted,and to a certain extent can reflect the Mihe River Basin.hydrological process.(2)The spatial correspondence between the SWAT hydrological response unit(HRU)and the MODFLOW orthogonal grid(CELL)was realized through ArcGIS,and the calculation result GW-RCHG of groundwater recharge in the SWAT output file was assigned to the planar recharge in MODFLOW The recharge module completes the coupling of surface water and groundwater based on SWAT-MODFLOW.On the basis of fully analyzing the hydrogeological conditions of the study area,a conceptual model of hydrogeology of the Mihe River Basin is established,and a mathematical model is further established to solve it,using the water level data of the groundwater monitoring wells in the study area from July 2016 to December 2018 Calibrate the model.The results show that the groundwater level simulation value and the monitoring well groundwater level observation value fit well.The coupling model can more realistically reflect the groundwater flow in the Mihe River Basin,and the coupling effect between surface water and groundwater in the Mihe River Basin is better.(3)On the basis of the constructed model,the influence of land use type on surface runoff and the influence of artificial exploitation on groundwater dynamics were further explored.Based on the SWAT model,the runoff was simulated using land use data in 1980,1990,2000,2010 and 2018,respectively.The results show that from 1980 to 2018,with the decrease of cultivated land and the increase of urban and rural industrial and mining residential land The average monthly runoff in the No.18 sub-basin during the simulation period showed an increasing trend every year,indicating that the reduction of cultivated land and the increase of urban and rural industrial,mining and residential land weakened the ability of surface infiltration,and at the same time was conducive to the confluence of surface runoff and the increase of runoff.Based on the SWAT-MOFLOW coupling model,three groundwater exploitation schemes are designed to maintain the current groundwater exploitation amount,reduce groundwater exploitation by 20%,and reduce groundwater exploitation by 50%to predict the groundwater level and groundwater balance in 2030.Under the condition of maintaining undisturbed mining,the groundwater balance in the study area is negative,and the water level fluctuates year by year.Compared with the plan of maintaining the undisturbed mining,the water level rebounded under the two mining reduction scenarios,and the scope and number of falling funnels were significantly reduced,and the groundwater balance in the study area showed a positive balance.A 20%reduction in groundwater extraction can achieve relatively ideal results.In the planning and management of groundwater resources in the Mihe River Basin,the focus should be on controlling the amount of groundwater extraction and rationally allocating the utilization of groundwater resources.