Modeling the Groundwater Recharge of Hormat-Golina sub-basin by Wetspass and MODFLOW coupling, Northern Ethiopia (Published)
The search for new groundwater resources in northern Ethiopia and the development of groundwater models to control and manage the resource are rooted in the water scarcity and the socio-economic importance of the water demand for agriculture and domestic use. In this paper, WetSpass-MODFLOW coupling was used to assess groundwater recharge of the Hormat-Golina sub-basin. This paper aims at determining the groundwater recharge in the Hormat-Golina sub-basin, which will be followed by simulating the hydraulic head distribution using the MODFLOW groundwater flow simulation model. The steady state groundwater flow calibration was achieved by comparing measured and simulated hydraulic heads. WetSpass also calculated the mean annual evapotranspiration, surface runoff, and groundwater recharge to be 516.6, 204.9, and 35.6 mm, respectively. Groundwater recharge represented 4.7% of precipitation, whereas actual evapotranspiration and surface runoff represented 27% and 68% of precipitation, respectively. For this type of seasonal variation, the range of groundwater head distribution is 9.37 to 29.86 m during the winter (dry season), 9.53 to 29.89 m during the summer (wet season), and 9.58 to 30.17 m during the annual stress periods (recharges). The predicted hydraulic heads in steady state match the measured heads well for all stress periods (summer, winter, and annual recharge) with a correlation coefficient of 0.86. Future groundwater resource development plans for the valley must be balanced with groundwater recharge rates and projected abstraction rates for agriculture and domestic water supply to ensure the long-term viability of this resource.
Keywords: Ethiopia, MODFLOW, groundwater recharge, hormat-golina, wetspass
Groundwater Recharge Assessment using WetSpass and MODFLOW: Case of Hormat-Golina sub-basin, Northern Ethiopia (Published)
Water scarcity in northern Ethiopia, as well as its socio-economic relevance in terms of water demand for agriculture and domestic use, are at the root of the search for new groundwater resources and the development of groundwater models that can be used to control and manage the resource. WetSpass-MODFLOW was used to estimate groundwater recharge in the Hormat-Golina sub-basin. The purpose of this study was to determine the amount of groundwater recharge in the Hormat-Golina sub-basin. Following that, the MODFLOW groundwater flow simulation model is utilized to simulate the hydraulic head distribution. The Steady-state groundwater flow calibration was determined by comparing measured and simulated hydraulic heads. The mean annual evapotranspiration, surface runoff, and groundwater recharge, according to WetSpass result, were 516.6, 204.9, and 35.6 mm, respectively. Groundwater recharge accounted for 4.7% of precipitation, while actual evapotranspiration and surface runoff accounted for 27%t and 68% of precipitation, respectively. In such seasonal variations (summer, winter and annual), the groundwater head distribution is 9.37 to 29.86m in winter (dry season), 9.53 to 29.89 m in summer (wet season), and 9.58 to 30.17 m in Annual stress periods (recharges). For all stress periods, the estimated hydraulic heads in steady-state fit well with the measured ones, with a correlation coefficient of 0.86 (summer, winter and annual recharge). The balance between groundwater recharge and expected abstraction rates for agriculture and domestic water supply must be considered in future groundwater resource development plans in the valley to ensure the resource’s long-term sustainability.
Keywords: Ethiopia, MODFLOW, groundwater recharge, hormat-golina, wetspass