Developing the groundwater-surface water interaction model in the Porsuk Basin

Groundwater and surface water interaction are crucial components of the natural water cycle and are highly significant for sustainable management of water resources. GSFLOW is a model developed to integrate the management of groundwater and surface water, incorporating various submodels such as MODFLOW (groundwater modeling) and PRMS (surface water modeling). In this study, the aim was to develop and detail a model of groundwater and surface water interaction in the Porsuk Basin. The accuracy of the models was evaluated through various calibration methods. The MODFLOW model was calibrated using both manual and PEST methods. The agreement between observed values and modeling results was assessed using statistical measures such as 'Mean Residual', 'Mean Absolute Residual' and 'RMSR' which were calculated as 1.45, 1.45, and 1.49, respectively, indicating the accuracy of the MODFLOW model. For the PRMS model, data from water year 1971 were used for modeling, calibrated using data from 1972, and verified using data from 1970. The calibration NSE value for PRMS was calculated as 0.98, and the validation NSE value was 0.97, demonstrating excellent performance of the PRMS surface water model. In the GSFLOW interaction model, an interaction model was established by integrating MODFLOW outputs from the SFR2 package with input data from the PRMS model. The NSE value for the calibration period of the GSFLOW model was 0.75, and for the validation period, it was 0.74, indicating satisfactory performance of the GSFLOW model.