Preprints
https://doi.org/10.5194/hess-2021-527
https://doi.org/10.5194/hess-2021-527

  01 Dec 2021

01 Dec 2021

Review status: this preprint is currently under review for the journal HESS.

Spatial and temporal simulation of groundwater recharge and cross-validation with point measurements in volcanic aquifers with variable topography

Alemu Yenehun1,2, Mekete Dessie3, Fenta Nigate1, Ashebir Sewale Belay1,2, Mulugeta Azeze3, Marc Van Camp2, Derbew Fenetie Taye6, Desale Kidane5,6, Enyew Adgo6, Jan Nyssen7, Ann van Griensven4, and Kristine Walraevens2 Alemu Yenehun et al.
  • 1School of Earth Sciences, Bahir Dar University, Bahir Dar, Ethiopia
  • 2Laboratory for Applied Geology and Hydrogeology, Department of Geology, Ghent University, Gent, Belgium
  • 3Faculty of Civil and Water Resources Engineering, Bahir Dar University, Bahir Dar, Ethiopia
  • 4Department of Hydrology and Hydraulic Engineering, Vrije Universiteit Brussel, Brussel, Belgium
  • 5Department of Soil Physics, Ghent University, Belgium
  • 6Department of Natural Resources, Bahir Dar University, Ethiopia
  • 7Department of Geography, Ghent University, Belgium

Abstract. A physically distributed water balance model called WetSpass is applied to estimate the recharge for the semi-humid Lake Tana basin in northwest Ethiopia. Lake Tana basin is one of the growth corridors of the country, where huge waterworks infrastructure is developing. Estimating groundwater recharge at required spatial and temporal scales is a challenge in groundwater management, sustainability and pollution studies. In this study, the WetSpass model is developed at 90 m grid resolution. The spatial recharge map by WetSpass is cross-validated with water table fluctuation (WTF) and chloride mass balance (CMB) methods. The mean annual recharge, surface runoff, and evapotranspiration over the whole basin using WetSpass are estimated at 315 mm, 416 mm, and 770 mm of rainfall, respectively. The mean annual recharge ranges from 0 mm to 1085 mm (0 % to 57 % of the rainfall): 0 mm at water bodies and highest on flat, sandy loam soil and bush land cover. Similarly, a high range of recharge is also noted using WTF and CMB methods showing the strong heterogeneous nature of the hydro(meteoro)logical characteristics of the area. Generally, the recharge is found higher in southern and eastern catchments and lower in the northern catchments, primarily due to higher rainfall amounts in the former parts. A fair general correlation between the recharge by WTF and WetSpass is found. WetSpass is effective in aquifers where diffuse recharging mechanism is the predominant type and recharge is controlled by rainfall. It is less effective in the storage-controlled flat floodplain alluvial and fractured rock aquifer areas. In these areas, the point estimates by WTF and CMB are effective and can be considered as reliable values. The land use change from 1986 to 2014 brought a relatively small hydrological change in recharge although the land use has changed significantly.

Alemu Yenehun et al.

Status: open (until 26 Jan 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2021-527', Anonymous Referee #1, 23 Dec 2021 reply

Alemu Yenehun et al.

Alemu Yenehun et al.

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Short summary
Population growth, industrial expansion, and climate change are causing stress on the limited freshwater resources of the globe. Groundwater is one of the important freshwater resources. Hence, managing these limited resources is a key task for the sector experts. To do so, understanding recharge processes and its quantification is vital. In this study, three different methods using measured data are applied to estimate recharge and identify the controlling factors.