Analysis and numerical modelling of large-scale controls on aquifer structure and hydrogeological properties in the African basement (Benin, West Africa)

Neil Dickson (Corresponding Author), Jean-Christophe Comte, Youssouf Koussoube, Ulrich S Ofterdinger, Jean-Michel Vouillamoz

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The metamorphic basement units of the Upper Ouémé watershed in Benin have been investigated to identify the structural controls on aquifer properties, groundwater flow and water balance at large scale. Spatial analysis of borehole and hydrogeophysical data suggests that large-scale weathering profiles, aquifer transmissivity and storage properties are better correlated to a palaeo-weathering surface. Multi-model analysis, combined with assessment of nine transient numerical groundwater models against observations, suggests the best conceptualizations are those where hydraulic conductivity and specific yield are distributed within a weathered zone determined through interpolation of weathered zone thickness. When compared to previous studies, the general groundwater balance of simulated models suggests the groundwater system contributes, on average, 49.8 m3 s−1 to the river flow (mostly during the rainy season). The same volumetric flow would be lost to groundwater evapo-transpiration and deep/lateral drainage of the catchment. Borehole abstraction (about 7.5 m3 s−1) represents only 6% of the average groundwater recharge and 1% of the average rainfall. This suggests that despite relatively low borehole productivity, the basement aquifer system still has an important unused potential for rural to mid-scale water supply and that, at present, the main external drivers for groundwater resource sustainability are changes in climate and land use.
Original languageEnglish
Pages (from-to)81-100
Number of pages20
JournalGeological Society Special Publications
Volume479
Issue number1
Early online date8 May 2018
DOIs
Publication statusPublished - 11 Apr 2019

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Aquifers
Groundwater
aquifer
Boreholes
groundwater
borehole
modeling
Weathering
Groundwater resources
weathering profile
Transpiration
Groundwater flow
structural control
Hydraulic conductivity
transmissivity
groundwater resource
Watersheds
Water supply
spatial analysis
river flow

Keywords

  • HARD-ROCK AQUIFERS
  • CONCEPTUAL-MODEL
  • GROUNDWATER
  • LINEAMENTS
  • INFERENCE
  • SELECTION
  • STORAGE
  • CYCLE

ASJC Scopus subject areas

  • Water Science and Technology
  • Ocean Engineering
  • Geology

Cite this

Analysis and numerical modelling of large-scale controls on aquifer structure and hydrogeological properties in the African basement (Benin, West Africa). / Dickson, Neil (Corresponding Author); Comte, Jean-Christophe; Koussoube, Youssouf; Ofterdinger, Ulrich S; Vouillamoz, Jean-Michel.

In: Geological Society Special Publications , Vol. 479, No. 1, 11.04.2019, p. 81-100.

Research output: Contribution to journalArticle

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