Ground water - surface water interaction and impact assessment, in the case of western Ziway catchment, in Ethiopia

The goal of this research was to enhance the current understanding of the interaction of surface water-ground water and impact assessment using a numerical model. Initially, to measure the natural recharge of the aquifer and to model streamflow, the surface water hydrology of the sub basin was researched using the HEC-HMS (SMA)model. The ground flow mechanism was analyzed by using 3D numerical groundwater flow model (Processing Modflow Pro (Version 5.3.0.1)). The HEC-HMS(SMA) model was used to measure the recharge rate for the sub-basin in order to achieve a recharge. Model calibration was subsequently carried out using the process of trial-and-error calibration using groundwater contours formed from heads collected at 56 observation points. Therefore, the average RMSE for simulated hydraulic heads was approximately 20. 65m.Simulated water levels in the model were more sensitive to decreases in recharge values and sensitive to decreases in hydraulic conductivity values. However, relative to recharge and hydraulic conductivity, the model is not as sensitive to decreases or increases in pump age. According to the simulation Lakes and rivers are significant sources of aquifer recharge. Finally, the model's water budget results showed that groundwater recharge comprised 81.48%, through river leakage 3.28% and constant head was 15.24% of the total water input for the entire study region. Because of this, it can be noted that the surface water impacts to the water budget of the sub-basin.