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Impact of flooding on microbiological contamination of domestic water sources: a longitudinal study in northern Ghana

Impact of flooding on microbiological contamination of domestic water sources: a longitudinal study in northern Ghana
Impact of flooding on microbiological contamination of domestic water sources: a longitudinal study in northern Ghana
Flooding is the most frequent natural hazard globally, but evidence of its impact on domestic water point contamination remains limited. This study aimed to assess dam-related flooding’s impact on microbiological contamination of rural water points and to evaluate agreement of satellite-derived flood maps with ground-based observations of water point flooding. Fieldwork took place in two Ghanaian districts frequently flooded following dam overspill. Fifty-seven water points were tested for bacterial parameters during and immediately after flooding. Forty water points were resampled in the dry season, with the remainder having run dry. Ground-based observations of flooding were compared with three satellite-derived flood maps. Boreholes were less contaminated than wells or surface waters (geometric mean E. coli = 20.2, 175.6, and 590.7 cfu/100 ml, respectively). Among groundwater points, a Wilcoxon signed-rank test indicated significantly greater median E. coli and thermotolerant coliform contamination during flooding (p = 0.025 and p < 0.001, respectively), but Shigella, salmonella, and intestinal enterococci counts were not significantly different between seasons. In contrast, among surface water points, E. coli, Shigella, and Salmonella counts were significantly greater in dry season samples (p < 0.005 for all parameters), possibly reflecting a “concentration” effect. Satellite-derived flood maps had no or low agreement with ground-based observations of water point flooding. Although groundwater quality deteriorated during and after flooding, surface waters were the most microbiologically contaminated in both seasons. The greatest public health risk thus occurred where households switched to surface water collection during or following flood season. Flood risk should be assessed before borehole installation and existing flood-prone boreholes remediated to mitigate population exposure to contaminated water.
Dzodzomenyo, Mawuli
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Asamoah, Moses
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Li, Chengxiu
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Kichana, Elvis
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Wright, Jim
94990ecf-f8dd-4649-84f2-b28bf272e464
Dzodzomenyo, Mawuli
f7969c6b-5999-448b-befa-e1c2e0287895
Asamoah, Moses
8bc7f17a-7432-44e0-ab9f-c2dd1cee1aaf
Li, Chengxiu
adaf46fc-1573-4c50-bd7f-b2e7ed048f7e
Kichana, Elvis
b58bd2fb-8ac2-46f4-815e-0b851b5974a5
Wright, Jim
94990ecf-f8dd-4649-84f2-b28bf272e464

Dzodzomenyo, Mawuli, Asamoah, Moses, Li, Chengxiu, Kichana, Elvis and Wright, Jim (2022) Impact of flooding on microbiological contamination of domestic water sources: a longitudinal study in northern Ghana. Applied Water Science, 12 (10), [235]. (doi:10.1007/s13201-022-01757-6).

Record type: Article

Abstract

Flooding is the most frequent natural hazard globally, but evidence of its impact on domestic water point contamination remains limited. This study aimed to assess dam-related flooding’s impact on microbiological contamination of rural water points and to evaluate agreement of satellite-derived flood maps with ground-based observations of water point flooding. Fieldwork took place in two Ghanaian districts frequently flooded following dam overspill. Fifty-seven water points were tested for bacterial parameters during and immediately after flooding. Forty water points were resampled in the dry season, with the remainder having run dry. Ground-based observations of flooding were compared with three satellite-derived flood maps. Boreholes were less contaminated than wells or surface waters (geometric mean E. coli = 20.2, 175.6, and 590.7 cfu/100 ml, respectively). Among groundwater points, a Wilcoxon signed-rank test indicated significantly greater median E. coli and thermotolerant coliform contamination during flooding (p = 0.025 and p < 0.001, respectively), but Shigella, salmonella, and intestinal enterococci counts were not significantly different between seasons. In contrast, among surface water points, E. coli, Shigella, and Salmonella counts were significantly greater in dry season samples (p < 0.005 for all parameters), possibly reflecting a “concentration” effect. Satellite-derived flood maps had no or low agreement with ground-based observations of water point flooding. Although groundwater quality deteriorated during and after flooding, surface waters were the most microbiologically contaminated in both seasons. The greatest public health risk thus occurred where households switched to surface water collection during or following flood season. Flood risk should be assessed before borehole installation and existing flood-prone boreholes remediated to mitigate population exposure to contaminated water.

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Accepted/In Press date: 2 September 2022
Published date: 15 September 2022
Additional Information: Funding Information: This work was funded through the ‘Building REsearch Capacity for sustainable water and food security in drylands of sub-Saharan Africa’ (BRECcIA, awarded to MD and JW) which is supported by the UK Research and Innovation ( https://www.ukri.org/ ) as part of the Global Challenges Research Fund, grant number NE/P021093/1. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Identifiers

Local EPrints ID: 470616
URI: http://eprints.soton.ac.uk/id/eprint/470616
PURE UUID: 84947e1e-6715-448e-adb3-bff223fbf949
ORCID for Jim Wright: ORCID iD orcid.org/0000-0002-8842-2181

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Date deposited: 14 Oct 2022 16:46
Last modified: 15 Oct 2022 01:39

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Contributors

Author: Mawuli Dzodzomenyo
Author: Moses Asamoah
Author: Chengxiu Li
Author: Elvis Kichana
Author: Jim Wright ORCID iD

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