Scielo RSS <![CDATA[Water SA]]> vol. 41 num. 5 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>A conceptual theoretical framework to integrally assess the possible impacts of climate change on domestic irrigation water use</b>]]> Southern Africa is likely to experience higher evapotranspiration and altered rainfall characteristics due to global warming and climate change. Climate-driven water use may potentially stress water supply facilities due to increased demand and reduced surface water yield. This paper presents a conceptual theoretical framework for assessing impacts of climate change on domestic irrigation water use. The prediction of climatic conditions that may potentially influence future water use is reviewed together with regional capacity for downscaling global climate projections. The impact assessment of water use is based on the modification and adaptation of an existing end-use model for water demand to include parameters for climate change. The Penman-Monteith equation and the soil water balance equation are incorporated for the estimation of daily water needs of vegetated areas in residential properties. The paper also discusses data requirements and a calibration procedure to improve model fit to the observed domestic irrigation water use. The proposed approach could form a basis for constructing a detailed model for planning various adaption measures relating to climate-driven domestic irrigation water use. <![CDATA[<b>The benthic regeneration of N and P in the Great Brak estuary, South Africa</b>]]> <![CDATA[<b>Assessment of metal leachability and toxicity from sediment potentially stored on land</b>]]> The aim of this study was to assess the toxicity and metal leachability from three dredged bottom sediments potentially stored on land. Washing out was conducted at a sediment dry mass to water mass ratio of 1:10. The method relies on washing out pollutants from the examined sample using water with third degree of purity in static/quasi-dynamic conditions. The investigations comprised three 27-h washing out cycles, including leaching in static conditions (19 h) and shaking (8 h). Bottom sediments are complex matrices; therefore laboratory tests cannot always reflect changes in physicochemical properties, which can potentially take place after a longer period of time. In spite of this, static-dynamic tests conducted under laboratory conditions provide information which enables a rough estimation of the potential threat posed by the studied sediment to the environment, at a given time. It was demonstrated that the leachability of metals during storage of polluted (Rybnik, Rzeszów) or unpolluted (Narozniki) bottom sediments does not pose a hazard to the environment. The Microtox test showed low toxicity of test water extracts. Considering their final destination, the potential and actual environmental hazards which the extracted bottom deposits pose should be assessed by determining the leachability of metals. <![CDATA[<b>Framework for optimizing chlorine dose in small - to medium-sized water distribution systems: A case of a residential neighbourhood in Lahore, Pakistan</b>]]> To maintain desirable residual chlorine for a groundwater source, optimizing the chlorine dose in small- to medium-sized water distribution systems (SM-WDS) is a daunting task in developing countries. Mostly, operators add a random chlorine dose without recognizing the smaller size of their distribution network. In this research, a modelling framework for optimizing chlorine dose in SM-WDS is developed. In order to evaluate its practicality, the proposed framework has been applied in a case study of a residential neighbourhood in Lahore (Pakistan) with a small network spanning over 0.35 km². Three datasets for residual chlorine were monitored at 6 locations spread over the study area. EPANET 2.0 software was used for hydraulic and residual chorine modelling. The bulk decay coefficient (Kb) was determined in the laboratory, whereas the wall decay coefficient (K ) was estimated by calibrating the simulation results with the residual chlorine determined in the field. Based on the calibrated EPANET simulations, a fuzzy rule-based model was developed for pragmatic application of the proposed framework. Scenario analyses for different situations have also been carried out for achieving residual chlorine required at the consumer end. This exercise revealed that much lower chlorine doses than the existing practice can generate detectable chlorine residuals. Moreover, the model can be used to deal with emergency situations, which may arise in developing countries due to viral outbreaks and cross-contamination events in SM-WDS. <![CDATA[<b>Piloting a method to evaluate the implementation of integrated water resource management in the Inkomati River Basin</b>]]> This paper provides an assessment of the implementation of principles of integrated water resource management (IWRM) in the Inkomati River Basin (IRB), shared by South Africa, Swaziland and Mozambique. A methodology with a set of principles, change areas and measures was developed as a performance assessment tool. The tool was piloted in the IRB and results from the application were used to refine and finalise the tool. Piloting of the tool did provide very useful insights into IWRM implementation in the IRB and highlighted gaps where future attention needs to focus. Good progress has been realised with respect to creating the enabling environment and institutional frameworks as the key principles of IWRM have been successfully articulated in policy and legislation and a relatively satisfactory degree of stakeholder participation achieved. Measures related to the IWRM implementation instruments seem to be the least developed, particularly the financial enabling environment and institutional capacity building change areas. More attention also needs to be paid to conflict resolution mechanisms. The results from the pilot also showed that countries should consider a phased approach to assessment of IWRM, as implementation does seem to follow a process of creating the enabling environment, followed by formulating and implementing the institutional framework and creation and application of IWRM management instruments. <![CDATA[<b>A reduction in mining and industrial effluents in the Blesbokspruit Ramsar wetland, South Africa: Has the quality of the surface water in the wetland improved?</b>]]> The Blesbokspruit Wetland, 40 km southeast of Johannesburg, South Africa, was listed as a Ramsar Wetland of International Importance in 1986. Following discharges of mine-waters in the mid-1990s, the wetland no longer complied with the Ramsar criteria. This paper reports on historical trends in surface water quality of the Blesbokspruit, as a step towards restoration to Ramsar status. Monthly water quality data (SO4, Na, Cl and Mg concentrations, pH and EC values), from January 2000 to December 2011, were obtained from Rand Water for sites at: the stream inflow, just after the discharge point of pumped underground mine-water from Grootvlei mine, and the stream outflow point. The major ions were grouped into two distinct time-variation patterns (SO4-Mg) and (Na-Cl). Despite extensive reports that the wetland had an acid mine drainage problem, the pH values over an 11-year period were constrained within a range of 6.7 to 8.8. In 2011, following the cessation of underground mine-water pumping operations, mineralisation of the Blesbokspruit showed a large stepwise reduction, in contrast to a slowly decreasing trend over the previous 10 years, in both the SO4-Mg and Na-Cl groups, and EC. The stepwise reduction suggests that the pulping plant within the paper mill, a major source of Na-Cl rich effluent, had ceased operations coincidentally with the cessation of underground water discharges. This contradicts previous findings that underground mine-water discharge was the principal contributor to contamination of the Blesbokspruit Wetland. So, while the Blesbokspruit may have had a high mineralisation problem, this was not simply an acid mine drainage problem, but a combination of the effects of mining and industry. <![CDATA[<b>Water institutions and governance models for the funding, financing and management of water infrastructure in South Africa</b>]]> The standard water institutions, governance and infrastructure reform and policy prescription package of the 1990s and early 2000s, i.e., restructuring, private-public partnerships (PPP), establishment of an independent regulator, have not yielded positive results for South Africa. These water institutions and governance challenges are resulting in inadequate investments, and millions in South Africa not having access to basic water and sanitation services. The framework for water sector infrastructure funding models was designed to meet the challenges presented by the current and growing imbalances that exist between the supply of and demand for water in South Africa. The research results identified 7 overarching governance models for the funding, financing and development of water infrastructure projects in South Africa, i.e. Model 1: direct fiscal (NRF) funding, Model 2: ring-fenced special purpose vehicle (SPV), Model 3: SPV housing dedicated water infrastructure cash-flows, Model 4: stand-alone water institution with strong balance sheet, Model 5: public-private partnership (PPP) with equity, Model 6: private concession, and Model 7: private development. Various institutional options for consideration for the future management and development of water infrastructure were investigated and considered. The emerging model is considered to be a hybrid model consolidating the national water resources and regional bulk infrastructure functions and capabilities, with regional bulk infrastructure primarily being a water board (water services provider) function. <![CDATA[<b>Passive remediation of acid mine drainage using cryptocrystalline magnesite: A batch experimental and geochemical modelling approach</b>]]> Acid mine drainage is generated when mining activities expose sulphidic rock to water and oxygen leading to generation of sulphuric acid effluents rich in Fe, Al, SO4 and Mn with minor concentrations of Zn, Cu, Mg, Ca, Pb depending on the geology of the rock hosting the minerals. These effluents must be collected and treated before release into surface water bodies. Mining companies are in constant search for cheaper, effective and efficient mine water treatment technologies. This study assessed the potential of applying magnesite as an initial remediation step in an integrated acid mine drainage (AMD) management system. Neutralization and metal attenuation was evaluated using batch laboratory experiments and simulations using geochemical modelling. Contact of AMD with cryptocrystalline magnesite for 60 min at 1 g: 100 ml S/L ratio led to an increase in pH, and a significant increase in metals attenuation. Sulphate concentration was reduced to =1 910 mg/l. PH redox equilibrium (in C language) (PHREEQC) geochemical modelling results showed that metals precipitated out of solution to form complex mineral phases of oxy-hydroxysulphates, hydroxides, gypsum and dolomite. The results of this study showed that magnesite has potential to neutralize AMD, leading to the reduction of sulphate and precipitation of metals. <![CDATA[<b>In-line rheological characterisation of wastewater sludges using non-invasive ultrasound sensor technology</b>]]> The performance of a new ultrasound transducer, which can measure velocity profiles non-invasively through high-grade stainless steel pipes, was evaluated for the first time with secondary wastewater sludges. This work is a follow-up study on the feasibility work initially done by the same authors. In-line process control based on accurate rheological characterisation for treated wastewater sludge could lead to significant savings in chemicals and will optimise dewatering processes producing drier sludges. In this work, a wastewater sludge at three concentrations was tested in order to investigate the capabilities of the in-line ultrasound technique for different viscosities and fluid properties. The rheological parameters obtained using the new ultrasound sensor and ultrasonic velocity profiling with combined pressure difference (UVP + PD) technique were compared with results obtained using conventional tube viscometry. Comparison with tube viscometer results showed that yield stresses could be overestimated by 120% if data are not available in the low shear-rate ranges. This non-invasive transducer proved to be sensitive enough to obtain flow curves over a large shear-rate range, improving the prediction of the yield stress and requiring about 50% less energy than the invasive system. <![CDATA[<b>Microbial water quality of treated water and raw water sources in the Harare area, Zimbabwe</b>]]> Microbial water quality is an essential aspect in the provision of potable water for domestic use. The provision of adequate amounts of safe water for domestic purposes has become difficult for most municipalities mandated to do so in Zimbabwe. Morton-Jaffray Treatment Plant supplies potable water to Harare City and areas surrounding Harare. This study investigated microbial water quality and the impact of microbial water quality related disasters in the area supplied by the Morton Jaffray Treatment Plant. Questionnaires were distributed to household owners in Harare who receive their water from the Municipality and those who use alternate water supplies. Candidates were randomly selected from their workplace. The raw water quality of Manyame River and its tributaries was assessed. Treated water in households was assessed for microbial quality using hydrogen sulphide test and heterotrophic bacteria plate count. Raw water sources were found to be contaminated by faecal matter. Household water sources tested negative for faecal contamination but positive for heterotrophic bacteria. CFU quantities ranged from 1 to 452 CFU/ml for all samples. The WHO guidelines for domestic water sources state that water used for domestic purposes should not be contain than 100 CFU/ml. Public perceptions of water quality ranged from 'unsafe' to 'highly contaminated'. A decrease in the level of aesthetic appeal resulted in residents resorting to alternative sources such as wells and rivers for their domestic water. The current state of treated water was suitable for domestic use. Pathogen monitoring of domestic water is recommended using the hydrogen sulphide test and R2A agar test. <![CDATA[<b>Apparent losses due to domestic water meter under-registration in South Africa</b>]]> This study investigated the extent of apparent losses due to water meter under-registration in South Africa. This was done by first estimating the under-registration of new meters due to on-site leakage, and then the additional under-registration due to meter aging. The extent and flow distributions of on-site leakage were determined through field studies in Cape Town, Mangaung and Johannesburg, by measuring the flow through new water meters when no legitimate consumption occurred on the property. The results were used in combination with the accuracy curves of new meters to estimate meter under-registration. The eThekwini meter replacement database was used to estimate the effect of meter age on meter accuracy. By combining these results with the average age of meters in South Africa, estimated from the National Water Demand Archive, it was possible to estimate the average meter under-registration due to meter aging. The study concluded that apparent losses due to water meter under-registration are around 5% of consumption for domestic consumers. <![CDATA[<b>The development of a classification system for inland aquatic ecosystems in South Africa</b>]]> A classification system is described that was developed for inland aquatic ecosystems in South Africa, including wetlands. The six-tiered classification system is based on a top-down, hierarchical classification of aquatic ecosystems, following the functionally-oriented hydrogeomorphic (HGM) approach to classification but incorporating structural attributes at the lower levels of the hierarchy. At Level 1, a distinction is made between inland, estuarine and shallow marine systems using the degree of connectivity to the open ocean as the key discriminator. Inland systems are characterised by the complete absence of marine exchange and/or tidal influence. At Level 2, inland systems are grouped according to the most appropriate spatial framework for the particular application. At Level 3, four primary Landscape Units are distinguished (Valley floor, Slope, Plain, Bench) on the basis of the topographic position within which a particular inland aquatic ecosystem is situated, in recognition of the influence that the landscape setting has over hydrological and hydrodynamic processes acting within an aquatic ecosystem. Level 4 identifies HGM Units, defined primarily according to landform, hydrological characteristics and hydrodynamics. The following primary HGM Units (or HGM Types), which represent the main units of analysis for the classification system, are distinguished at Level 4A: (1) River; (2) Floodplain Wetland; (3) Channelled Valley-Bottom Wetland; (4) Unchannelled Valley-Bottom Wetland; (5) Depression; (6) Seep; (7) Wetland Flat. Secondary discriminators are applied at Level 5 to classify the hydrological regime of an HGM Unit, and Descriptors at Level 6 to categorise a range of biophysical attributes. The HGM Unit at Level 4 and the Hydrological Regime at Level 5 together constitute a Functional Unit, which represents the focal point of the classification system. The utility of the classification system is ultimately dependent on the level to which ecosystem units are classified, which is in turn constrained by the type and extent of information available. <![CDATA[<b>Fish community of a small, temperate, urban river in South Africa</b>]]> Freshwater and marine-spawned fishes were sampled from the Baakens River, a small urban river that runs through the city of Port Elizabeth in the Eastern Cape of South Africa. Using fyke nets, 8 sites were sampled along the river course over a 4-month period (January - April 2014). Catches were comprised of indigenous freshwater, marine migrant and alien fishes. Marine migrant fishes, including catadromous species dependent on freshwater for early life-history strategies, were significantly affected by instream barriers which prohibited upstream migration of all species except Anguilla mossambica. The freshwater fish fauna was dominated by Tilapia sparrmanii and Pseudocrenilabrus philander, species that are alien to the Baakens River. While indigenous Barbus pallidus and Sandelia capensis were both abundant and widely distributed in the river, only two Pseudobarbus afer were sampled from one survey site. The low abundance and narrow distribution of this endangered species is of concern and human-mediated impacts on this species require urgent evaluation and mitigation. <![CDATA[<b>Improving the accuracy of estimation of eutrophication state index using a remote sensing data-driven method: A case study of Chaohu Lake, China</b>]]> Trophic Level Index (TLI) is often used to assess the general eutrophication state of inland lakes in water science, technology, and engineering. In this paper, a data-driven inland-lake eutrophication assessment method was proposed by using an artificial neural network (ANN) to build relationships from remote sensing data and in-situ TLI sampling. In order to train the net, Moderate Resolution Imaging Spectroradiometer (MODIS, which has a revisit cycle of 4 times per day) data were combined with in-situ observations. Results demonstrate that the TLI obtained directly from remote-sensing images using the data-driven method is more accurate than the TLI calculated from the water quality factors retrieved from remote-sensing images using a multivariate regression method. Spatially continuous and quasi-real time results were retrieved by using MODIS data. This method provides an efficient way to map the TLI spatial distribution in inland lakes, and provides a scheme for increased automation in TLI estimation. <![CDATA[<b>Infrastructure for irrigation of grapevines with diluted winery wastewater in a field experiment</b>]]> Winemaking produces large volumes of poor quality water. The possibility to re-use this water for vineyard irrigation was investigated in a field trial. For this purpose, winery wastewater had to be diluted to chemical oxygen demand (COD) levels ranging between 100 and 3 000 mg/l. The relatively simple infrastructure and procedure required to dilute the winery wastewater in 15 m³ tanks are described. Analyses of the diluted winery wastewater confirmed that the COD concentrations were reasonably close to the target values. Furthermore, measuring COD concentrations in the irrigation water while it was being pumped from the tanks confirmed that the concentrations of diluted wastewater within the tanks were fairly homogeneous, and that effective mixing had taken place while tanks were being filled. The COD measurements were more reliable when the oxidation time was standardised at 2 h compared to shorter periods, irrespective of the level of COD in the water. After initial practical problems and sources of error were eliminated, the accuracy of treatment application obtained in terms of the target COD concentrations was acceptable. <![CDATA[<b>Conductivity as an indicator of surface water quality in the proximity of ferrochrome smelters in South Africa</b>]]> South Africa is one of the leading ferrochrome (FeCr) producing countries. One of the main environmental and health-related issues associated with FeCr production is the possible generation of Cr(VI). However, Cr(VI) is not the only potential pollutant that has to be considered during FeCr production. Various water-soluble species are present in FeCr waste materials and in process water. Considering the size of the South African FeCr industry and its global importance, it is essential to assess the extent of potential surface water pollution in the proximity of FeCr smelters by such water-soluble species. In this study water conductivity was measured as a proxy of general water quality. Although deposition was not measured, comparison of surface water results indicated that atmospheric deposition of pollutants originating from FeCr smelting did not significantly impact surface water quality, but that surface run-off and/or groundwater leaching were the main contributors. At two FeCr smelters it was observed that these smelters did not impact surface water quality negatively. In contrast, surface water pollution originating from at least four FeCr smelters was apparent. However, only at one smelter did pollution result in surface water conductivity that indicated a water quality not fit for human consumption. No correlations could be made between potable water quality and possible pollution from FeCr smelters. Notwithstanding this limitation, it was found that potable water sampled at all sites complied with the conductivity criteria for human consumption. <![CDATA[<b>The history of South African inland fisheries policy with governance recommendations for the democratic era</b>]]> The governance of South Africa's inland fishery resources in the democratic era has lacked a guiding policy, supporting legislation and government capacity based on the social, economic and environmental objectives defined in constitutional legislation. This is ironic, as during the colonial and apartheid eras South Africa had developmentally orientated inland fishery policies with supporting institutions. An overview of the evolution of inland fishery policy in South Africa is provided, beginning with the comprehensive colonial policies to develop Inland Fisheries Divisions and recreational fisheries based on the introduction of alien species. Apartheid-era policies to promote commercial fisheries on dams in the Free State and small-scale fisheries in the former homelands are described. A policy shift in the 1980s saw the provincial nature conservation agencies move away from promoting inland fisheries based on alien species to conserving indigenous fish fauna. This effectively ended a century of state-supported inland fishery development, resulting in a decline in state-supported inland fishery institutions and a policy vacuum which has not been addressed in the democratic era. Customary and traditional small-scale fishing rights and practices have never been recognised in policy and governance arrangements resulting in the progressive marginalisation of these fisheries. The inclusion of the inland fishery mandate into the Fisheries Branch of the newly-formed Department of Agriculture, Forestry and Fisheries in 2009 was a positive move opening the way for the re-establishment of institutional arrangements to promote equity and optimal socio-economic benefit from inland fisheries. The need for an inland fishery policy and institutional capacity aligned with democratic South Africa's development objectives and environmental management policies is motivated. Policy objectives are recommended based on a characterisation of the potential of the inland fishery resource and its user groups, international norms for fishery governance, and consultations with public and private sector stakeholders on appropriate governance and institutional arrangements. <![CDATA[<b>Sublethal effects of temperature on freshwater organisms, with special reference to aquatic insects</b>]]> Water temperature is a key variable affecting aquatic organisms. Understanding their response to elevated water temperatures is important for estimating upper thermal limits, and ultimately for assisting with setting defendable, biologically-relevant water temperature guidelines for lotic systems. Sublethal effects impacting on an individual organism or species may manifest at higher levels of the hierarchy, namely, populations, communities and entire ecosystems. Sublethal effects typically include those affecting an organism's physiology and metabolism (e.g. growth rates, secondary productivity, respiration); phenology (e.g. development time, voltinism, emergence); reproductive success and fitness (e.g. fecundity, rates and success of egg development and hatching); behaviour (e.g. migration, movement, drift); and broad-scale ecological effects (e.g. species richness, composition, density, distribution patterns). Sublethal effects are discussed with examples drawn from freshwater studies, in particular those focused on aquatic insects. Commonly-used methods, which vary from simple, cost-effective, laboratory-based methods to more elaborate, expensive, laboratory- and field-based studies, are assimilated to serve as a toolbox for future thermal research. Ultimately, the method adopted depends largely on the question(s) being asked and available resources.