Using geological domains to characterise regional to continental scale aquifers across eastern Africa

MacAllister, Donald John ORCID: https://orcid.org/0000-0001-8893-9634; Palamakumbura, Romesh; MacDonald, Alan ORCID: https://orcid.org/0000-0001-6636-1499; Macdonald, David; Krabbendam, Maarten; Reeves, Teddy; Murphy, Ben; Ketema, Abede; Tessema, Zenaw; Gicheruh, Chrysanthus; Benedicto van Dalen, Daniela; Kleinendorst, Theo. 2024 Using geological domains to characterise regional to continental scale aquifers across eastern Africa. [Poster] In: World Groundwater Congress IAH 2024 Davos, Davos, Switzerland, 8-13 Sept 2024.

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Abstract/Summary

We have developed a geological domains-approach to characterise the spatial variability of key aspects of the geology that directly impact the hydrogeology of aquifers at different scales. This approach utilises a range of datasets, including geological maps, terrain maps, satellite imagery, research papers and thematic datasets such as fault maps or climatic zones to develop a set of spatial geological domains. The specific variables and subsurface depth represented by the domains will depend on the objective of the specific mapping exercise and/or the type of hydrogeological modelling being undertaken. The quality of geological and geomorphological spatial data can be highly variable on a regional to continental-scale and this be qualitatively represented with a a description of the uncertainty of each individual domain. The domains approach can either data-driven or conceptual model driven, typically when working at a site to catchment scale. Where data is readily available a data-driven approach can be implemented. However, at a continent-scale, where spatial data is less likely to be available, a conceptual model-driven approach is needed. This requires a hypothesis of key geological and landscape processes to be developed, which can be used to create a domains map based on a continental-scale geological maps and terrain data. To illustrate this process, we will demonstrate the use of the domains approach to characterise groundwater properties of the shallow aquifer across a range of geological settings in northern Kenya, Somalia and Somaliland. The geology of the region included Archean basement, the East African Rift and several major Cenozoic basins, with a variable Quaternary cover. The domains focused on the spatial variability of regional-scale faults, bedrock lithology and potential weathering profiles (regolith).

Item Type:	Publication - Conference Item (Poster)
Additional Pages:	Session 4.01. Groundwater Mapping: methodological developments from the sub-national to continental scale
Additional Keywords:	GroundwaterBGS, IGRD
Date made live:	17 Sep 2024 15:25 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/538036

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