Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Integrated hydrological modeling of groundwater rechrage and groundwater resources in the Auob Catchment (Namibia).

Auteur : Kamundu Kamuiua

Etablissement de soutenance : University of Twente

Grade : Master of Science in Geo-Information Science and Earth Observation 2019

Résumé
Part of the Auob Catchment is suited within the Stampriet artesian basin. The basin is experiencing a decline in the water levels, which triggered a proposed reduction of up to 50% water use in the area. There is a burning need for the implementation of intervention methods such as artificial recharge. The current study aims at understanding the spatio-temporal distribution of natural groundwater recharge of the system and groundwater resources distribution as well as at identifying potential artificial recharge zones (by injection wells) that can further be used in scenario analysis. In order to account for the spatio-temporal distribution of groundwater fluxes, MODFLOW-NWT model was created. This model was calibrated in trial and error manner. The 5-year model simulation (1/09/2012-31/08/2017) show that 94.44% of precipitation (P) is distributed over the catchment as effective precipitation while 67.53% of P percolates as gross recharge. Most of the water is lost via groundwater evapotranspiration (ETg), which accounts for 68.74% of P, unsaturated zone evapotranspiration (ETuz) contributing 24.01% of P and groundwater exfiltration (Exfg) which represents 19.74% of P. Thus, creating a negative net recharge (Rn) of -20.95 % of P. The abstraction in the area accounts for 0.17% of P. Potential recharge zones and injection well locations have been proposed based on the analysis of natural recharge processes on the model solution.

Mots clés : Groundwater Recharge, Groundwater Resources, Spatio-temporal Variability, MODFLOWNWT, Integrated Hydrological Model.

Version intégrale (ITC)