Technical note: An inorganic water chemistry dataset (1972–2011) of rivers, dams and lakes in South Africa

Huizenga, Jan Marten; Silberbauer, Michael; Dennis, Rainier; Dennis, Ingrid

doi:10.4314/wsa.v39i2.18

Cited by 7 publications

(8 citation statements)

References 6 publications

(8 reference statements)

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“…In addition to the flow gauging information, water quality measurements are available from the resource quality database [14]. The water resource quality database contains many inconsistencies in chemical analysis results, which the user needs to take into consideration before using the data [15].…”

Section: Flow Network Datamentioning

confidence: 99%

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Social Paradigm Shift Required to Counter the Eutrophication of the Hartbeespoort Dam in South Africa

Dennis

2019

WIT Transactions on Ecology and the Environment

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Sewage discharges are poisoning major rivers and dams in South Africa, including the Hartbeespoort Dam. High nutrient concentrations promote algae growth, leading to eutrophication. The dam has been in a hypertrophic state since the early 1970s. Mismanagement of waste water treatment works (WWTWs) within the catchment area are largely to blame, with over 280 tons of phosphate and nitrate deposits. Point source pollution in the form of malfunctioning WWTWs and diffuse sources from informal settlements present along streams and rivers within the catchment area, are responsible for the high nutrient levels. Many of these settlements use water directly from the river/stream. The first step to address the problem of eutrophication is by reducing the nutrient source. A conservative mass transport model was developed to predict phosphate levels and was used to assess the impact on the dam. The average phosphate levels entering the dam is 0.72 mg/L and the target to reduce algae growth is 0.15 mg/L. Various treatment options were investigated to solve the problem, but these efforts were mainly focused on treating the symptoms rather than the cause and treatment options were very costly. Legislation regarding water pollution this is in place, but is not enforced by government. The model predictions indicate that even if all WWTWs reach a zero discharge of phosphates, the required target will still not be met. It is concluded that the only feasible option would be a paradigm shift in the social behaviour of people living in informal settlements and this paradigm shift requires education. More often than not, scientists and engineers only consider technical solutions. The result of this study underlines the importance of a transdisciplinary approach, involving scientists and the rural communities to reach an effective solution.

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Section: Flow Network Datamentioning

confidence: 99%

“…In 2011 a snapshot of the water quality database was taken and has been extensively modified, which included the removal of incomplete analyses and the addition of extra chemical variables calculated from concentrations of the major ions [15]. This augmented water quality dataset was chosen for the analysis.…”

Section: Flow Network Datamentioning

confidence: 99%

Social Paradigm Shift Required to Counter the Eutrophication of the Hartbeespoort Dam in South Africa

Dennis

2019

WIT Transactions on Ecology and the Environment

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“…In South Africa, the Department of Water Affairs (DWA) has co-ordinated an extensive National Chemical Monitoring Programme (NCMP) since the early 1970s, which comprises in excess of 2000 monitoring stations situated in rivers, dams and lakes throughout the country (Huizenga, 2011;Huizenga et al, 2013). Chemical variables that are monitored include: inorganic nutrients (N, P and Si), pH, electrical conductivity, total dissolved solids, as well as a variety of other major chemical …”

Section: Introductionmentioning

confidence: 99%

“…sodium, calcium, potassium, magnesium, chloride, fluoride, and sulphate) (Huizenga, 2011;Huizenga et al, 2013). Despite its obvious benefits, there are numerous shortcomings associated with the NCMP, including geographical bias in site selection, tendency for intermittent datasets, and the 'inter-station' variability regarding dataset sizes (Huizenga, 2011).…”

mentioning

confidence: 99%

Nutrient characterisation of river inflow into the estuaries of the Gouritz Water Management Area, South Africa

Lemley

Taljaard²,

Adams³

et al. 2014

WSA

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This study provides an overview of the nutrient status of river inflow into the estuaries within the Gouritz Water Management Area (WMA) of South Africa. Riverine inputs are a major source of macronutrients to estuaries and the adjacent coastal environments. Long-term water quality monitoring data (dissolved inorganic nitrogen, i.e. DIN; and dissolved inorganic phosphorus, i.e. DIP), collected by the Department of Water Affairs (DWA), were used to assess historical trends of river nutrient inflow within the Gouritz WMA. The results indicate that DIP concentrations exceeded the eutrophic limits for aquatic ecosystems (DWA) in 50% of the catchments assessed. Anthropogenic activities such as agriculture, wastewater discharge, urbanisation, and afforestation were significant factors influencing nutrient levels within these rivers. For the majority of the river systems (approx. 80%) there was no significant correlation (P > 0.05) between inorganic nutrient levels and freshwater inflow from the catchments. Wastewater treatment plant (WWTP) data (DWA) were assessed to explore the reasons for this 'disconnect' between freshwater inflow and inorganic nutrient levels. The Gwaing and Hartenbos estuaries would be most vulnerable to increased nutrient loading because of their small size and prolonged periods of mouth closure. The study highlights the importance of water quality monitoring of river inflows into coastal ecosystems, as it is needed to assess pollution trends and identify management priorities.

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“…The South African national water quality database stores data records from several environmental monitoring programmes, including the National Chemical Monitoring Programme (NCMP), under the management of the national Department of Water and Sanitation (DWS). The NCMP comprises extensive surface water monitoring programmes that have collected data from lakes, dams and rivers across South Africa since the 1960s (Huizenga 2011;Huizenga et al, 2013). Chemical variables monitored include major cations, anions, compounds and indicators, such as: Ca 2+ (calcium), Mg 2+ (magnesium), K + (potassium), Na + (sodium) and NH 3--P (orthophosphate), F -(fluoride), SiO 2 (silica), pH, electrical conductivity, Total Dissolved Solids (TDS) and total alkalinity (Huizenga et al, 2013).…”

Section: -mentioning

confidence: 99%

Technical note: An anomaly in pH data in South Africa’s national water quality monitoring database – implications for future use

Ramjukadh

Silberbauer²,

Taljaard

2018

WSA

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The South African national water quality database (Water Management System) houses data records from several environmental monitoring programmes, including the National Chemical Monitoring Programme (NCMP). The NCMP comprises an extensive surface water quality monitoring programme, managed by the Department of Water and Sanitation (DWS). The purpose of this technical note is to alert users to a systematic anomaly recently observed in the pH dataset of the NCMP, reflected in an abrupt increase between pre- and post-1990 data records. Although the cause of the anomaly in pH could not be confirmed with high confidence, an inappropriate acid rinse procedure in pre-1990 analytical methods was identified as the most likely cause, based on available evidence. This was supported by the variation in relative sensitivity when comparing the effect on waters with different buffering capacities, i.e., water with low buffering capacity (represented by total alkalinity < 10 mg/L, as CaCO3) showing the largest anomaly, compared with waters of higher buffering capacity (represented by total alkalinity > 30 mg/L, as CaCO3) showing the smallest anomaly. Historical pH data records in the NCMP (i.e. pre-1990), therefore should be used with caution, especially in more weakly buffered systems. The possibility of reconstructing data using a correction factor derived from detailed statistical analyses of the post-1990 pH characteristics at selected sites is a possible solution that could be investigated in future. A key lesson learnt is the need to be diligent in capturing detailed meta-data on sampling procedures and analytical methods in datasets spanning several generations. Availability of such information is critical in order to provide users with a means of evaluating the suitability and comparability of data records in long-term datasets. The DWS includes such meta-data in the current version of the database, dating from about 1995 onwards.

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Technical note: An inorganic water chemistry dataset (1972–2011) of rivers, dams and lakes in South Africa

Cited by 7 publications

References 6 publications

Social Paradigm Shift Required to Counter the Eutrophication of the Hartbeespoort Dam in South Africa

Social Paradigm Shift Required to Counter the Eutrophication of the Hartbeespoort Dam in South Africa

Nutrient characterisation of river inflow into the estuaries of the Gouritz Water Management Area, South Africa

Technical note: An anomaly in pH data in South Africa’s national water quality monitoring database – implications for future use

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