Numerical Groundwater Flow Modeling of the Megech River Catchment, Tana Sub Basin, North Western Ethiopia

Abstract

The study area is found in Amhara Regional State, North Gondar Administrative Zone, Gondar town and surrounding Keble of river catchment. It’s total area coverage is 785 km 2 with main lithologic units of lacustrine deposit, Middle Basalt (Aiba) and Upper basalt (Alajie).Numerical Groundwater Flow Modeling of the Megech River Catchment, Tana Sub Basin is conducted with the objective of simulating the groundwater flow system of the area and to evaluate the response of the hydrogeological system under different stress, so that the resulting consequence on the system can be estimated.The calibrated statistics of the model area with Mean Error (ME) of 4.8, Absolute Mean Error (AME) of 4.9, and Root Mean Square Error value of 6.8 (RMSE), which is an indicator of good calibration. The sensitive parameter of the model was identified during calibration process. Based on this, hydraulic conductivity and recharge is sensitive in RMSE than River Conductance values. The simulated water budget at steady state condition of Megech river catchment is analyzed. The simulated inflow of the model is 1.0703551E+06 m 3 /day which is equal to simulated outflow 1.0703559E+06 m 3 /day with difference -7.9617882E-01(-0.79617882) m 3 /day. The groundwater system of Megech Catchment total withdrawals of the well is 1.78853E+04m3/day. Scenario analysis was conduct in recharge decreasing and increasing of withdrawals rate. Keywords: calibration, water budget, simulation, Scenario, steady state, numerical groundwater flow modeling, sensitive, Tana sub basin, Megech River, groundwater withdrawal. DOI: 10.7176/JEES/12-6-01 Publication date: June 30 th 2022