An evaluation of groundwater vulnerability assessment methods in a rapidly urbanizing city: evidence from Dakar, Senegal

Abstract In rapidly growing cities in the tropics, unregulated urban development presents a major risk to groundwater quality. Here, we assess vulnerability of an unconfined aquifer Quaternary sands Thiaroye area Dakar (Senegal) contamination using four GIS-based indices (DRASTIC, DRASTIC_N, SINTACS, SI). Our correlation assessed observed impact is semi-quantitative, relating quality, based on nitrate concentrations and tryptophan-like fluorescence degrees (i.e. coincidence rates). We show that considerably more has “very high vulnerability” according SI (36%) relative DRASTIC (5%) SINTACS (9%); “high estimated DRASTIC_N (100%), (66%) (69%). Single-parameter sensitivity tests depth, soil, topography, land use redox parameters strongly influence assessments vulnerability. Correlation with reveals better represented by (coincidence rates 56%) (43%), (38%) (34%). The underestimation DRASTIC, attributed their reliance assumed capacity unsaturated zone attenuate surface or near-surface contaminant loading, which low-income (Thiaroye) thin affords limited protection. inclusion land-use parameter improves characterization this low-income, urbanizing Dakar.