Assessing groundwater recharge in crystalline and karstic aquifers of the Upper Crocodile River Basin, Johannesburg, South Africa

Leketa, Khahliso; Abiye, Tamiru; Zondi, Silindile; Butler, Michael J.

doi:10.1016/j.gsd.2018.08.002

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…Recharge elevations have been estimated with groundwater δ 18 O data in dozens of areas around the globe (Table ; e.g., Gonfiantini et al, ; Carreira et al, ; Marques et al, ; N'da et al, ; Leketa et al, ; Tsuchihara et al, ). Studies are concentrated, unsurprisingly, in areas of high topographic relief, including the northern China, Morocco, Ethiopia, Europe, and mountain ranges spanning the Americas (Figure ).…”

Section: Recharge Sources and Elevationsmentioning

confidence: 99%

Global Isotope Hydrogeology―Review

Jasechko

2019

Reviews of Geophysics

230

124

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Groundwater 18O/16O, 2H/1H, 13C/12C, 3H, and 14C data can help quantify molecular movements and chemical reactions governing groundwater recharge, quality, storage, flow, and discharge. Here, commonly applied approaches to isotopic data analysis are reviewed, involving groundwater recharge seasonality, recharge elevations, groundwater ages, paleoclimate conditions, and groundwater discharge. Reviewed works confirm and quantify long held tenets: (i) that recharge derives disproportionately from wet season and winter precipitation; (ii) that modern groundwaters comprise little global groundwater; (iii) that “fossil” (>12,000‐year‐old) groundwaters dominate global aquifer storage; (iv) that fossil groundwaters capture late‐Pleistocene climate conditions; (v) that surface‐borne contaminants are more common in younger groundwaters; and (vi) that groundwater discharges generate substantial streamflow. Groundwater isotope data are disproportionately common to midlatitudes and sedimentary basins equipped for irrigated agriculture, but less plentiful across high latitudes, hyperarid deserts, and equatorial rainforests. Some of these underexplored aquifer systems may be suitable targets for future field testing.

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Section: Recharge Sources and Elevationsmentioning

confidence: 99%

Global Isotope Hydrogeology―Review

Jasechko

2019

Reviews of Geophysics

230

124

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“…2) on the catchment boundary. This was confirmed in Leketa et al (2019), where the long-term groundwater samples from a spring (Albert Farm spring (AF); Fig. 1) that discharges from the fractured quartzite were studied and found to resemble the isotopic signature of rainfall, inferring the occurrence of recharge from rainfall, possibly through the vertical fractures in quartzite (Fig.…”

Section: Introductionmentioning

confidence: 60%

Investigating stable isotope effects and moisture trajectories for rainfall events in Johannesburg, South Africa

Leketa

Abiye

2020

WSA

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This study investigated the isotopic composition of daily rainfall in Johannesburg from November 2016 to October 2018. The moisture sources and trajectories for rainfall events of extreme isotopic signatures were deduced using the Hybrid Single Particle Lagrangian Integrated Trajectory model (HYSPLIT). The results from time series and regression analysis show temperature and amount effects, with low coefficient of determination (R2) values of 0.21 and 0.12, respectively. The rainfall with amounts of <20 mm yielded a meteoric water line (MWL) with a slope of +6.9 and deuterium excess (d-excess) of +11.9‰. Rainfall with amounts of ≥20 mm had slope and d-excess values of +8.2 and +18.6‰, respectively. The lower slope in rainfall of <20 mm indicated the preferential occurrence of sub-cloud re-evaporation on light rainfall. Considering the lack of re-evaporation in heavy rainfall (≥20 mm), its slope and d-excess were approximated to those of incoming or in-cloud moisture prior to condensation. Therefore, a high d-excess of +18.6‰ in incoming moisture indicates evaporation that mainly occurs under warm sea surface temperature and low relative humidity. HYSPLIT shows that the moisture for the most depleted and the most enriched rainfall originates in the higher latitudes but differs in trajectory. The moisture for the most depleted rainfall had long residence in the higher latitudes following a semi-direct trajectory to Johannesburg, over the Atlantic and Indian Oceans. The most enriched rainfall followed a curved anticlockwise trajectory with long residence in the lower latitudes over the Indian Ocean. Circulation of saturated moisture over the warm Indian Ocean leads to a loss of light isotopes, thereby enhancing enrichment in the moisture that moves further inland. HYSPLIT indicated the importance of atmospheric conditions along the moisture trajectory on the signature of Johannesburg rainfall.

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“…In the present study, camallanids were collected from C. gariepinus in Lake Heritage, upstream of Boomker's (1982) sampling site. Since his study, this river system has been exposed to severe levels of pollution, mainly from gold mine effluent releases in the form of acid mine drainage (AMD) which has exacerbated over time ( Department of Water Affairs and Forestry, S.A, 2008 ; Abiye et al, 2015 ; Leketa et al, 2019 ; Atta et al, 2020 ; Shapi et al, 2021 ; Windisch et al, 2022 ). Measures to counteract this have been implemented such as water treatment plants, cedar-needle compost bags and upstream lime filtration ( Durand, 2012 ; Atta et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%