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Stellenbosch University (2021)

Potential impacts of climate change on groundwater recharge in South Africa using stable isotopes of water

Ramudzuli, Khahuliswe Edson

Titre : Potential impacts of climate change on groundwater recharge in South Africa using stable isotopes of water

Auteur : Ramudzuli, Khahuliswe Edson

Université de soutenance : Stellenbosch University

Grade : Master Degree (Earth Sciences) 2021

Résumé
Unimodal wet season precipitation plays a significant role in ensuring sustainable and continuous replenishment of groundwater resources, especially in arid to semi-arid climates that only recharge during these seasons in heavy rainfall events. Therefore, changes in precipitation patterns (i.e., the frequency, intensity, and duration of precipitation events) may effectively threaten the reliability and sustainability of groundwater resources. This study investigates the relationship between stable water isotope composition of groundwater and precipitation samples collected across the different climatic zones in South Africa. The analysis was done to deduce the evaporative conditions experienced by precipitation before groundwater recharge, which in turn assisted in extrapolating how various changes in climatic conditions would translate to groundwater recharge (e.g., induced evaporative loss of rainfall). Both precipitation and groundwater samples showed a proper alignment with the Global Meteoric Water Line (GMWL) and respective LMWLs with a dispersion that increased from the O- and H- isotope depleted sections towards the enriched areas. Groundwater samples showed relative characteristics with wet season precipitation plotting along the same regionality on respective Local Meteoric Water Lines (LWMLs). The secondary evaporation of precipitation, noted by the deviation of groundwater samples from the GMWL and respective LMWLs, increased from the south-western and east coasts, which receive relatively higher precipitation amounts towards the interior, south, and west coast of the country, which are somewhat dryer. This analysis will assist in the forecasting of future groundwater recharge patterns in response to climate change

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Page publiée le 6 juin 2022