Surface and groundwater hydrochemistry of the Menengai Caldera geothermal field and surrounding Nakuru County, Kenya

Montcoudiol, N., Burnside, N. M. , Györe, D. , Mariita, N., Mutia, T. and Boyce, A. (2019) Surface and groundwater hydrochemistry of the Menengai Caldera geothermal field and surrounding Nakuru County, Kenya. Energies, 12(16), 3131. (doi: 10.3390/en12163131)

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In order to assess the sustainability and impact of production from geothermal reservoirs on hydrological systems, a thorough understanding of local and regional hydrogeological systematics is a prerequisite. The Menengai Caldera in the Kenya Great Rift Valley is one of the largest explored geothermal fields in the country. This paper presents a hydrochemical investigation of the Menengai Caldera geothermal field and the ground and surface waters of the surrounding Nakuru County. Our results demonstrated a similar, sodium-alkaline dominated, ionic composition across all water types. Geothermal wells return the highest cation/anion concentrations and largely demonstrate a meteoric source from their δ18O and δ2H signature. Wells MW-09 (central part of the caldera), MW-18 (eastern part) and MW-20 (central part) showed a more evaporitic signature, closely matching with our own calculated Lake Evaporation Line, suggesting an increased mixing influence of Lake Nakuru waters. MW-09 also showed evidence of high-temperature oxygen isotopic exchange and significant water-rock interaction. Lake samples largely demonstrated seasonal shifts in ionic and isotopic values. Lake Nakuru ionic composition and isotopic values increased throughout the 12-month wet–dry–wet season sampling period. This correlated with a decrease in area which suggests a lessening of water inflow and facilitates increased evaporation. Groundwaters demonstrated clear evidence of mixing between meteoric, irrigation and lake waters. These observations enhanced the understanding of the hydrological system surrounding the Menengai Caldera and, when combined with future studies, will provide a powerful tool to assess the sustainability and impact of soon-to-be completed geothermal power production operations.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Boyce, Professor Adrian and Burnside, Dr Neil and Gyore, Dr Domokos and Montcoudiol, Dr Nelly
Creator Roles:
Burnside, N. M.Conceptualization, Methodology, Formal analysis, Writing – original draft, Supervision, Project administration, Funding acquisition
Boyce, A.Conceptualization, Methodology, Formal analysis, Writing – review and editing, Supervision, Funding acquisition
Montcoudiol, N.Formal analysis, Data curation, Writing – original draft, Supervision
Györe, D.Writing – review and editing, Supervision
Authors: Montcoudiol, N., Burnside, N. M., Györe, D., Mariita, N., Mutia, T., and Boyce, A.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Energies
ISSN (Online):1996-1073
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Energies 12(16):3131
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
748351EPSRC-GCRF ISF 2016: Reconciling low-carbon energy and sustainable water use in one of the worlds poorest regions: geothermal development in EthiopiaNeil BurnsideEngineering and Physical Sciences Research Council (EPSRC)EP/P510968/1ENG - ENGINEERING SYSTEMS POWER & ENERGY
3006630Geothermally Sourced Power and Freshwater Generation for Eastern AfricaZhibin YuEngineering and Physical Sciences Research Council (EPSRC)EP/P028829/1ENG - Systems Power & Energy
767361SFC-GCRF: Geothermal Understanding in Developing Economies (GUIDE): Strengthening relationships and building baseline data in the East African Rift ValleyNeil BurnsideScottish Funding Council (SFC)SFC/AN/15/2016ENG - ENGINEERING SYSTEMS POWER & ENERGY