The role of superficial geology in controlling groundwater recharge in the weathered crystalline basement of semi-arid Tanzania

Zarate, E., Hobley, D. ORCID: https://orcid.org/0000-0003-2371-0534, MacDonald, A. M., Swift, R. T., Chambers, J., Kashaigili, J. J., Mutayoba, E., Taylor, R. G. and Cuthbert, M. O. ORCID: https://orcid.org/0000-0001-6721-022X 2021. The role of superficial geology in controlling groundwater recharge in the weathered crystalline basement of semi-arid Tanzania. Journal of Hydrology: Regional Studies 36 , 100833. 10.1016/j.ejrh.2021.100833

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Abstract

Study region Little Kinyasungwe River Catchment, central semi-arid Tanzania. Study focus The structure and hydraulic properties of superficial geology can play a crucial role in controlling groundwater recharge in drylands. However, the pathways by which groundwater recharge occurs and their sensitivity to environmental change remain poorly resolved. Geophysical surveys using Electrical Resistivity Tomography (ERT) were conducted in the study region and used to delineate shallow subsurface stratigraphy in conjunction with borehole logs. Based on these results, a series of local-scale conceptual hydrogeological models was produced and collated to generate a 3D conceptual model of groundwater recharge to the wellfield. New hydrological insights for the region We propose that configurations of superficial geology control groundwater recharge in dryland settings as follows: 1) superficial sand deposits act as collectors and stores that slowly feed recharge into zones of active faulting; 2) these fault zones provide permeable pathways enabling greater recharge to occur; 3) ‘windows’ within layers of smectitic clay that underlie ephemeral streams may provide pathways for focused recharge via transmission losses; and 4) overbank flooding during high intensity precipitation events increases the probability of activating such permeable pathways. These conceptual models provide a physical basis to improve numerical models of groundwater recharge in drylands, and a conceptual framework to evaluate strategies (e.g., Managed Aquifer Recharge) to artificially enhance the availability of groundwater resources in these regions.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences Water Research Institute (WATER)
Additional Information:	This is an open access article under the CC BY-NC-ND license
Publisher:	Elsevier
ISSN:	2214-5818
Funders:	NERC
Date of First Compliant Deposit:	25 May 2021
Date of Acceptance:	11 May 2021
Last Modified:	03 May 2023 21:44
URI:	https://orca.cardiff.ac.uk/id/eprint/141548

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