Estimating Groundwater Evapotranspiration in Thiaroye Aquifer (Western Senegal)
The use of diurnal or seasonal water table fluctuation (WTF) to estimate groundwater evapotranspiration (ETG) is increasing applied in ecohydrological studies. In this study, we applied the WTF method for a shallow aquifer in Senegal over the dry season 2000–2013. To analyze the applicability and validity of the WTF method for this site, the unsaturated/saturated system was first simulated using the 1-D HYDRUS model. The simulated drawdown of the water table over the 14 years ranges from 18.1 to 113.2 cm, and from 10.4 to 101.9 cm for a bare soil and a perennial grass scenario and is highly related to the annual rainfall of the previous rainy season. The results indicate that the estimated actual evapotranspiration (ETa) from the Hydrus model ranged between 0.22 and 1.11, and between 0.23 and 1.27 mm d−1 in bare soil and vegetative condition, respectively. Results indicate that higher ETa values were observed when the water table is shallow, suggesting that ETa is driven mainly by the water table depth.
KeywordsEvapotranspiration Water table fluctuation Semi-arid regions Unsaturated zone
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