Interaction Between Groundwater And Surface Water Under Large-scale Exploitation Conditions Based On SWAT-MODFLOW Model

Yanqi Basin is a typical arid oasis irrigated area in northwest China.Surface irrigation water resources and groundwater resources are important components of water resources in the basin.In recent years,the continuous increase of groundwater extraction has led to a series of water shortage problems due to the implementation of water-saving transformation projects in arid irrigated areas.Therefore,integrated mitigation strategies and tools for surface and groundwater are becoming increasingly important in the field of hydrology and water resources research.In this paper,an integrated approach(SWAT-MODFLOW)based on the Soil and Water Assessment Tool(SWAT)and the Modular 3D Finite-Differential Groundwater Model(MODFLOW)was used for research.That is,the recharge and evaporation values are calculated by SWAT model,and then input into MODFLOW for groundwater numerical simulation research.Based on the comprehensive consideration of the implementation of high-efficiency water-saving irrigation project,the control of groundwater overextraction and the reasonable ecological depth of groundwater level,different groundwater exploitation scenarios were set up,and the coupling model was input to predict the variation characteristics of groundwater level in arid oasis irrigation area and lake wetland under each scenario.The main research conclusions are as follows:(1)A distributed hydrological model based on SWAT is constructed in this paper,which based on DEM data,land use data,soil data,CMADS and traditional hydrometeorological data from 1955 to 2016.And,we used the SUFI-2 algorithm to analyze the parameters sensitivity,and the main parameters affecting the runoff simulation results were calibrated by SWAT-CUP software.We used fielded runoff data of Yanqi Hydrological Station from 1991 to 2016 were to verify the model.Results show that the Yanqi basin in Xinjiang for a long time scales runoff simulated values and measured values coincide well,regularly and validation period Nash model rate coefficient of NES>0.71,Pearson correlation coefficient R~2 of 0.88 and0.95 respectively,suggesting that the SWAT model in Yanqi basin of good applicability.(2)In this study,the data of HRU-cell between SWAT and MODFLOW were integrated and based on Arc GIS10.2 software,that is,we constructed a SWAT-MODFLOW coupling model in the basin according to the characteristics of surface hydrological cycle and groundwater recharge,path and discharge.The model is calibrated and verified by using the water level data of 15 long-observation Wells in the study area.The hydraulic conductivity is 0?90 m/d,and the specific yield is 0.1?0.25,both of which belong to the effective and reasonable range.(3)This paper uses coupled SWAT-Modflow model to realize the prediction and prediction of groundwater level in the Yanqi Basin in 2050 by considering the influence of human activities.We set five groundwater mining situations by the elements of reducing groundwater exploitation and combining surface water displacement of groundwater,and the annual exploitation volume of each situation is6.46×10~8m~3,5.26×10 ~8m~3,4.58×10~8m~3,4.09×10~8m~3 and 3.65×10~8m~3respectively.Five exploitation situations in the basin were simulated to 2050,and the results show that the water table has declined significantly.According to the simulation and prediction results of each situation,it is determined that the sustainable exploitation of groundwater in Yanqi Basin,which meets the demand of sustainable development of irrigation agriculture,4.09×10~8 m~3/a.