Research Article
Assessment of Recharge Dynamics Under Extreme Rainfall Using Groundwater Fluctuations and Stable Isotopes Signatures: Insights from an Urban Observatory in Dakar
Issue:
Volume 14, Issue 5, October 2025
Pages:
118-133
Received:
28 August 2025
Accepted:
10 September 2025
Published:
25 September 2025
Abstract: Rapid urbanization across sub-Saharan Africa intensifies water supply challenges, making groundwater an essential resource for meeting the needs of low-income urban communities. However, the recurrence of extreme rainfall events due to climate change present major challenges for sustainable groundwater management, particularly in urban areas where infrastructures often impedes natural recharge processes and simultaneously amplifies flood risks. Here we investigate the recharge dynamics of the Thiaroye quaternary sand aquifer in Dakar, Senegal, under extreme rainfall conditions, based on high resolution monitoring of groundwater fluctuations and stable isotope analysis. The study combines high-frequency hydrological data from the Dakar suburban groundwater observatory, with isotopic signatures (δ18O and δ2H) to trace recharge processes and contamination risks. Results indicate that high to extreme rainfall events (>10 mm.d-1) are the primary drivers of groundwater level fluctuations, with an identified threshold of approximately 9 mm needed for effective recharge. The isotopic analysis confirms consistent recharge conditions primarily influenced by local rainfall despite substantial variability in precipitation isotopic composition. This research underscores the critical need for improved groundwater management strategies to enhance urban resilience against extreme climatic events such as heavy to extreme rainfall, bridging the knowledge gap regarding groundwater recharge mechanisms in rapidly urbanizing areas like Dakar.
Abstract: Rapid urbanization across sub-Saharan Africa intensifies water supply challenges, making groundwater an essential resource for meeting the needs of low-income urban communities. However, the recurrence of extreme rainfall events due to climate change present major challenges for sustainable groundwater management, particularly in urban areas where ...
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Research Article
Assessing ENACTS and CHIRPS Precipitation Estimates in Jimma Zone, Ethiopia
Endeshaw Shewangizaw Gebremedhin*
Issue:
Volume 14, Issue 5, October 2025
Pages:
134-146
Received:
20 September 2025
Accepted:
30 September 2025
Published:
27 October 2025
DOI:
10.11648/j.wros.20251405.12
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Abstract: The availability of satellite and other climate datasets has significantly advanced for hydro-climatic studies. However, these climatic products still face substantial uncertainties. Thus, the main objectives of this paper was to assess the performance of ENACTS and CHIRPS version 2 precipitations from 1991 to 2020 in the daily, monthly, seasonal level, annual and during wet/dry year based on observed ground station data over Jimma Zone, Oromia, Ethiopia. The two products were evaluated by using correlation coefficient (CC), root mean square error (RMSE), mean absolute error (MAE), and percentage bias (PBIAS) against gauge data from ground station. On a daily scale, ENACTS exhibits a correlation coefficient (CC) of 0.43, indicating a strong positive relationship with observed rainfall, while CHIRPS has a lower CC of 0.34, reflecting a weaker correlation. ENACTS shows a root mean square error (RMSE) of 8.2 mm and a mean absolute error (MAE) of 4.5 mm, suggesting high accuracy and relatively low average prediction error. In contrast, CHIRPS has an RMSE of 7.4 mm and an MAE of 4.6 mm, indicating fewer discrepancies but slightly less precision. On a monthly scale, ENACTS demonstrates a robust CC of 0.96, significantly outperforming CHIRPS, which has a CC of 0.87. ENACTS's RMSE is 29.9 mm with an MAE of 23.8 mm, while CHIRPS has a higher RMSE of 59.8 mm and an MAE of 47.3 mm. Additionally, ENACTS outperforms CHIRPS across all seasons—Belg, Kiremt, and Bega—with CCs of 0.75, 0.65, and 0.75, respectively, particularly excelling in replicating observed precipitation patterns during the Bega (dry) and Belg (short rainy) seasons. Overall, ENACTS consistently demonstrates superior correlation and accuracy in rainfall predictions compared to CHIRPS across all time scales and seasonal contexts. Therefore, this findings show that Both ENACTS and CHIRPS are more effective at the monthly time scale compared to the daily level, whereas the ENACTS re-mains the more accurate product across all time scales in the Jimma zone. This findings show that both ENACTS and CHIRPS are more effective at the monthly time scale, with correlation coefficients of 0.96 and 0.87, respectively, compared to the daily level, where the coefficients are 0.43 and 0.34. ENACTS remains the more accurate product across all time scales in the Jimma zone. This finding is crucial for guiding the selection of the most suitable precipitation products for agricultural planning, water resource management, and climate adaptation strategies in the region.
Abstract: The availability of satellite and other climate datasets has significantly advanced for hydro-climatic studies. However, these climatic products still face substantial uncertainties. Thus, the main objectives of this paper was to assess the performance of ENACTS and CHIRPS version 2 precipitations from 1991 to 2020 in the daily, monthly, seasonal l...
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