Using stable water isotopes to identify spatial-temporal controls on groundwater recharge in two contrasting East African aquifer systems

Samson Oiro (Corresponding Author), Jean-Christophe Comte, Chris Soulsby, Kristine Walraevens

Research output: Contribution to journalArticle

2 Citations (Scopus)
4 Downloads (Pure)

Abstract

Understanding the spatial-temporal variability in groundwater recharge is an essential prerequisite to sustainable management of aquifers. Spatial analysis of groundwater stable isotopes uncovered predominant controls on groundwater recharge in Nairobi Aquifer System (NAS) and South Coast aquifer (SC), two exemplar East-African aquifers relied upon by 7M people. 368 samples were analysed for stable isotopes and basic physico-chemical parameters. The NAS groundwater isotopes are controlled by precipitation orographic effects and enriched recharge from impounded lakes/wetlands. SC isotopes are correlated with water-table depth influencing evapotranspiration. Global Network of Isotopes in Precipitation-GNIP data revealed groundwater recharge during months of heavy rains in NAS, whilst SC experiences spatiotemporally diffuse recharge. Inferred ‘isoscapes’ show; in NAS, (1) direct, rapid recharge favoured by faults, well-drained soils and ample rainfall in uplands, (2) delayed recharge from impounded-lakes and wetlands in midlands, (3) focussed, event-based recharge in floodplains; in SC, diffuse recharge complicated by significant water-table evapotranspiration processes.
Original languageEnglish
Pages (from-to)862-877
Number of pages16
JournalHydrological Sciences Journal
Volume63
Issue number6
Early online date18 Apr 2018
DOIs
Publication statusPublished - 6 Jun 2018

Fingerprint

recharge
aquifer
isotope
groundwater
water
coast
evapotranspiration
water table
stable isotope
wetland
orographic effect
lake
spatial analysis
floodplain
well
rainfall

Keywords

  • Groundwater recharge
  • Stable isotopes
  • Aquifer systems
  • Meteoric water line
  • Evaporation effect

Cite this

Using stable water isotopes to identify spatial-temporal controls on groundwater recharge in two contrasting East African aquifer systems. / Oiro, Samson (Corresponding Author); Comte, Jean-Christophe; Soulsby, Chris; Walraevens, Kristine.

In: Hydrological Sciences Journal, Vol. 63, No. 6, 06.06.2018, p. 862-877.

Research output: Contribution to journalArticle

@article{d81affc34583480e953548858c9b399f,
title = "Using stable water isotopes to identify spatial-temporal controls on groundwater recharge in two contrasting East African aquifer systems",
abstract = "Understanding the spatial-temporal variability in groundwater recharge is an essential prerequisite to sustainable management of aquifers. Spatial analysis of groundwater stable isotopes uncovered predominant controls on groundwater recharge in Nairobi Aquifer System (NAS) and South Coast aquifer (SC), two exemplar East-African aquifers relied upon by 7M people. 368 samples were analysed for stable isotopes and basic physico-chemical parameters. The NAS groundwater isotopes are controlled by precipitation orographic effects and enriched recharge from impounded lakes/wetlands. SC isotopes are correlated with water-table depth influencing evapotranspiration. Global Network of Isotopes in Precipitation-GNIP data revealed groundwater recharge during months of heavy rains in NAS, whilst SC experiences spatiotemporally diffuse recharge. Inferred ‘isoscapes’ show; in NAS, (1) direct, rapid recharge favoured by faults, well-drained soils and ample rainfall in uplands, (2) delayed recharge from impounded-lakes and wetlands in midlands, (3) focussed, event-based recharge in floodplains; in SC, diffuse recharge complicated by significant water-table evapotranspiration processes.",
keywords = "Groundwater recharge, Stable isotopes, Aquifer systems, Meteoric water line, Evaporation effect",
author = "Samson Oiro and Jean-Christophe Comte and Chris Soulsby and Kristine Walraevens",
note = "We appreciate the financial support granted by the Royal Geography Society (with IBG), the Kenya Water Resources Management Authority (WRMA) and the University of Aberdeen. WRMA staff who assisted during groundwater sampling and J. Dick’s assistance in running isotope laboratory tests are greatly acknowledged. We are grateful to two anonymous reviewers for their relevant comments and suggestions which have contributed to improve the manuscript.",
year = "2018",
month = "6",
day = "6",
doi = "10.1080/02626667.2018.1459625",
language = "English",
volume = "63",
pages = "862--877",
journal = "Hydrological Sciences Journal",
issn = "0262-6667",
publisher = "Taylor and Francis Ltd.",
number = "6",

}

TY - JOUR

T1 - Using stable water isotopes to identify spatial-temporal controls on groundwater recharge in two contrasting East African aquifer systems

AU - Oiro, Samson

AU - Comte, Jean-Christophe

AU - Soulsby, Chris

AU - Walraevens, Kristine

N1 - We appreciate the financial support granted by the Royal Geography Society (with IBG), the Kenya Water Resources Management Authority (WRMA) and the University of Aberdeen. WRMA staff who assisted during groundwater sampling and J. Dick’s assistance in running isotope laboratory tests are greatly acknowledged. We are grateful to two anonymous reviewers for their relevant comments and suggestions which have contributed to improve the manuscript.

PY - 2018/6/6

Y1 - 2018/6/6

N2 - Understanding the spatial-temporal variability in groundwater recharge is an essential prerequisite to sustainable management of aquifers. Spatial analysis of groundwater stable isotopes uncovered predominant controls on groundwater recharge in Nairobi Aquifer System (NAS) and South Coast aquifer (SC), two exemplar East-African aquifers relied upon by 7M people. 368 samples were analysed for stable isotopes and basic physico-chemical parameters. The NAS groundwater isotopes are controlled by precipitation orographic effects and enriched recharge from impounded lakes/wetlands. SC isotopes are correlated with water-table depth influencing evapotranspiration. Global Network of Isotopes in Precipitation-GNIP data revealed groundwater recharge during months of heavy rains in NAS, whilst SC experiences spatiotemporally diffuse recharge. Inferred ‘isoscapes’ show; in NAS, (1) direct, rapid recharge favoured by faults, well-drained soils and ample rainfall in uplands, (2) delayed recharge from impounded-lakes and wetlands in midlands, (3) focussed, event-based recharge in floodplains; in SC, diffuse recharge complicated by significant water-table evapotranspiration processes.

AB - Understanding the spatial-temporal variability in groundwater recharge is an essential prerequisite to sustainable management of aquifers. Spatial analysis of groundwater stable isotopes uncovered predominant controls on groundwater recharge in Nairobi Aquifer System (NAS) and South Coast aquifer (SC), two exemplar East-African aquifers relied upon by 7M people. 368 samples were analysed for stable isotopes and basic physico-chemical parameters. The NAS groundwater isotopes are controlled by precipitation orographic effects and enriched recharge from impounded lakes/wetlands. SC isotopes are correlated with water-table depth influencing evapotranspiration. Global Network of Isotopes in Precipitation-GNIP data revealed groundwater recharge during months of heavy rains in NAS, whilst SC experiences spatiotemporally diffuse recharge. Inferred ‘isoscapes’ show; in NAS, (1) direct, rapid recharge favoured by faults, well-drained soils and ample rainfall in uplands, (2) delayed recharge from impounded-lakes and wetlands in midlands, (3) focussed, event-based recharge in floodplains; in SC, diffuse recharge complicated by significant water-table evapotranspiration processes.

KW - Groundwater recharge

KW - Stable isotopes

KW - Aquifer systems

KW - Meteoric water line

KW - Evaporation effect

U2 - 10.1080/02626667.2018.1459625

DO - 10.1080/02626667.2018.1459625

M3 - Article

VL - 63

SP - 862

EP - 877

JO - Hydrological Sciences Journal

JF - Hydrological Sciences Journal

SN - 0262-6667

IS - 6

ER -