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

Abstract

Small reservoirs (SRs) are essential water storage infrastructures for rural populations of Sub-Saharan West 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 buffer 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.

Impact of Dense Networks of Reservoirs on Streamflows at Dryland Catchments

“…In addition to the small reservoirs, the population of these regions usually uses wells for supply. The impact of small reservoirs on groundwater recharge is still unknown for dense networks of reservoirs at dryland catchments [55,56].…”

Environmental determinants of E. coli, link with the diarrheal diseases, and indication of vulnerability criteria in tropical West Africa (Kapore, Burkina Faso)

“…Poor microbial water quality is often associated with high relative percentages of cultivated land in both tropical and temperate regions [ 99 , 100 ]. The watershed of the Bagre Reservoir has undergone profound changes since the 1980s with an increase in cultivated areas and bare soils to the detriment of natural vegetation [ 67 , 68 , 101 ], which may have resulted in increased erosion and particle transport towards the lake. This type of land use can also alter the size of the particles [ 102 ] leading to increases in the proportion below 5μm [ 103 ].…”

Environmental determinants ofE. coli, link with the diarrheal diseases, and indication of vulnerability criteria in tropical area (Kapore, Burkina Faso)

“…Poor microbial water quality is often associated with high relative percentages of cultivated land in both tropical and temperate regions [99][100]. The watershed of the Bagre Reservoir has undergone profound changes since the 1980s with an increase in cultivated areas and bare soils to the detriment of natural vegetation [67,68,101], which may have resulted in increased erosion and particle transport towards the lake. This type of land use can also alter the size of the particles [102] leading to increases in the proportion below 5µm [103].…”