Small Reservoirs, Landscape Changes and Water Quality in Sub-SaharanWest Africa

Type Article
Date 2020-07
Language English
Author(s) Cecchi Philippe1, 2, Forkuor Gerald3, Cofie Olufunke4, Lalanne Franck5, Poussin Jean-Christophe6, Jamin Jean-Yves7
Affiliation(s) 1 : MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Montpellier, France
2 : CRO, BP V18 Abidjan 08, Cote D’Ivoire
3 : Institute for Natural Resources in Africa (UNU-INRA), United Nations University, Accra, Ghana
4 : International Water Management Institute (IWMI), PMB CT 112 Accra, Ghana
5 : 2iE, Institut International d’Ingénierie de l’Eau et de l’Environnement, 01 BP 594 Ouagadougou, Burkina Faso
6 : IRD G-EAU, Irstea, BP 5095 Montpellier, France
7 : CIRAD G-EAU, Irstea, BP 5095 Montpellier, France
Source Water (2073-4441) (MDPI), 2020-07 , Vol. 12 , N. 7 , P. 1967 (25p.)
DOI 10.3390/w12071967
Note This article belongs to the Section Aquatic Systems—Quality and Contamination
Keyword(s) small reservoirs, sub-Saharan Africa, anthropogenic pressures, water quality
Abstract

Small reservoirs (SRs) are essential water storage infrastructures for rural populations of Sub-SaharanWest Africa. In recent years, rapid population increase has resulted in unprecedented land use and land cover (LULC) changes. Our study documents the impacts of such changes on the water quality of SRs in Burkina Faso. Multi-temporal Landsat images were analyzed to determine LULC evolutions at various scales between 2002 and 2014. Population densities were calculated from downloaded 2014 population data. In situ water samples collected in 2004/5 and 2014 from selected SRs were analyzed for Suspended Particulate Matter (SPM) loads, an integrative proxy for water quality. The expansion of crop and artificial areas at the expense of natural covers controlled LULC changes over the period. We found a very significant correlation between SPM loads and population densities calculated at a watershed scale. A general increase between the two sampling dates in the inorganic component of SPM loads, concomitant with a clear expansion of cropland areas at a local scale, was evidenced. Results of the study suggest that two complementary but independent indicators (i.e., LULC changes within 5-km bu er areas around SRs and demographic changes at watershed scale), relevantly reflected the nature and intensity of overall pressures exerted by humans on their environment, and locally on aquatic ecosystems. Recommendations related to the re-greening of peripheral areas around SRs in order to protect water bodies are suggested.

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