Groundwater quality, quantity, and recharge estimation on the West Coast of South Africa

Miller, Jodie; Watson, Andrew B.; Fleischer, Melanie; Eilers, Anya; Sigidi, N.T.; Gend, Jani van; Rooyen, Jared van; Clarke, Catherine E.; Clercq, Willem de

doi:10.7809/b-e.00309

Cited by 2 publications

(3 citation statements)

References 2 publications

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“…Comparisons between the predicted groundwater isotope ratios and that of local modern precipitation would also contribute to determining whether or not the groundwater being extracted was likely recharged recently or is non-renewable 12 . The use of other geochemical tracers may further distinguish between modern and fossil groundwater aquifers 38 , 39 .…”

Section: Discussionmentioning

confidence: 99%

Seasonal variation in tap water δ2H and δ18O isotopes reveals two tap water worlds

Wet

West

Harris

2020

Sci Rep

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Stable isotope ratios of hydrogen and oxygen (δ 2 H and δ 18 O) in tap water provide important insights into the way that people interact with and manage the hydrological cycle. Understanding how these interactions vary through space and time allows for the management of these resources to be improved, and for isotope data to be useful in other disciplines. The seasonal variation of δ 2 H and δ 18 O in tap water within South Africa was assessed to identify municipalities that are supplied by seasonally invariant sources that have long residence periods, such as groundwater, and those supplied by sources that vary seasonally in a manner consistent with evapoconcentration, such as surface water—the proposed two tap water “worlds”. Doing so allows for the cost-effective spatial interpolation of δ 2 H and δ 18 O values that likely reflect that of groundwater, removing the residual error introduced by other sources that are dependent on discrete, isolated factors that cannot be spatially generalised. Applying the proposed disaggregation may also allow for the efficient identification of municipalities that are dependent on highly variable or depleted surface water resources, which are more likely to be vulnerable to climate and demographic changes.

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Section: Discussionmentioning

confidence: 99%

Seasonal variation in tap water δ2H and δ18O isotopes reveals two tap water worlds

Wet

West

Harris

2020

Sci Rep

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“…Daily totals of precipitation and solar radiation, mean daily relative humidity, temperature, windspeed and maximum and minimum daily temperature were collected for the period 1988-2002 (including a 2-year initialization period). The data were attained from the World Meteorological Organisation (WMO) as global surface summary of the day (GSOD) data [23], as well as the Agricultural Research Council (ARC), the South African Weather Services (SAWS), the Department of Water Affairs and Sanitation, South Africa (DWS), the South African Earth Observation Network [45] and previous JAMS/J2000 model data [18,[46][47][48][49][50]. In total, 97 precipitation, 24 temperature, 12 relative humidity, 15 windspeed and seven solar radiation stations were used (Table 2).…”

Section: Climate Inputsmentioning

confidence: 99%

“…However, often it is difficult to identify whether these sensitivities can be caused by anthropogenic factors, whether the noise-to-frequency (water balance) ratio causes anomalously high parameter sensitivity and where distinct streamflow characteristics are responsible for parameter uncertainty. As a result of the observed streamflow characteristics, the effective modelling area and anthropogenic factors, the model parameters selected from the automated calibration for Verlorenvlei, Eerste and Bot were 'unrealistic' in a regional context (Figure 8) and impact the uncertainty of previous studies [47][48][49]. While in general the selection of large catchments for regional hydrologically related assessment within a specified region provide lower uncertainty [86], multiple adjacent model applications are still required for catchments affected by anthropogenic factors and regionally unrepresentative streamflow characteristics.…”

Section: Effect Of Streamflow Characteristics On Regional Hydrological Modellingmentioning

confidence: 99%

Determining Hydrological Variability Using a Multi-Catchment Model Approach for the Western Cape, South Africa

et al. 2021

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Understanding the impacts of climate change requires the development of hydrological modelling tools. However, data scarcity hinders model application, performance, process simulation and uncertainty, especially for Sub-Saharan Africa. In this study, a multi-catchment approach was used to assess hydrological process variability in the Western Cape (WC) of South Africa using the JAMS/J2000 rainfall–runoff model and a Monte Carlo analysis (MCA). Due to much steeper slopes and lower evapotranspiration, the models suggest that WC is dominated by surface runoff from mountainous regions and regional groundwater flow. The results highlight the impact of the catchment size, availability and position of hydroclimatic and anthropogenic factors and the frequency of the signal-to-noise ratio (water balance). For large catchments (>5000 km2), the calibration was able to achieve a Nash–Sutcliffe efficiency (NSE) of 0.61 to 0.88. For small catchments (<2000 km2), NSE was between 0.23 to 0.39. The large catchments had an overall surface runoff, interflow and baseflow contribution of 44, 19 and 37%, respectively, and lower overall uncertainty. The simulated flow components for the small catchments were variable and these results are less certain. The use of a multi-catchment approach allows for identifying the specific factors impacting parameter sensitivities and in turn provides a means to improve hydrological process simulation.

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Groundwater quality, quantity, and recharge estimation on the West Coast of South Africa

Abstract: Climate change and adaptive land management in southern Africa -assessments, changes, challenges, and solutions. Biodiversity & Ecology, 6, Klaus Hess Publishers, Göttingen & Windhoek.

Cited by 2 publications

References 2 publications

Seasonal variation in tap water δ2H and δ18O isotopes reveals two tap water worlds

Seasonal variation in tap water δ2H and δ18O isotopes reveals two tap water worlds

Determining Hydrological Variability Using a Multi-Catchment Model Approach for the Western Cape, South Africa

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