Abstract:
Groundwater is the most valuable source of freshwater on earth. For groundwater development,
conservation, and implementing management plans efficiently, groundwater potential
identification is important. In Temcha catchment, groundwater is being misused and
management is weak. The purpose of part of this study is to assess and identify the groundwater
potential zones using GIS and remote sensing approach. The relative weights of the influencing
factors (lithology, slope, geomorphology, soil, lineament density, rainfall, drainage density, and
land use and land cover) were assigned using the Analytic Hierarchy Process (AHP) based on
Saaty’s 1–9 scale. The delineated potential zone has been divided into five categories: very poor
(1.189%,), poor (19.188%), moderate (40.452%), high (28.559%, and very high (10.612%).
As the sensitivity analysis shows lithology and slope are sensitive and influential and drainage
density is the least sensitive. The validation result shows a good agreement with 73.33%. The
developed groundwater potential zone will simplify the identification of locations for wells to be
drilled and be helpful for development and water resource management. The goal of groundwater
flow modelling in this study is to describe the groundwater quantitatively and to investigate the
aquifer response for external hydrologic stresses in the Dijil catchment. A single layer
unconfined aquifer two-dimensional conceptual model has been developed and simulated by
MODFLOW-NWT code under steady state. The manual trial and error method was used to
calibrate the model based on 18 observation points and its performance was evaluated through
summary statistics and graphical techniques. The calibration result shows that the RMSE is
6.013m which satisfy the criterion. The scenario analysis indicates that Adisna-Gulit well site
(DMTW#1, 2 &3) show large drawdown up to 45.20m. The river leakage and subsurface outflow
also investigated. As the withdrawal rate increases, the river leakage increases linearly and
subsurface outflow increase highly as the withdrawal rate increases. Additionally as the
withdrawal rate increase and recharge rate reduced, the flow from the river to the aquifer
increased and from the aquifer to the river was reduced. The sensitivity analysis result shows that
hydraulic conductivity and recharge rate are more sensitive. From the simulated water budget, the
total inflow-outflow is 1.4872m
3
/s with zero budget discrepancy.
