Research and Development Projects

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    Total Maximum Daily Load (TMDLs) Feasibility Study

    The TMDL protocol, originally developed for the USA Clean Water Act, provides a robust means of disaggregating the total load of a specific pollutant to a specific waterbody, by source. As such the approach allows for effective management of loadings, as well as supporting the "polluter-pays" principle. The protocol is data and skills intensive, aspects that may limit its application in South Africa. DHEC has been awarded a two-year contract to conduct a case-study based feasibility assessment and to identify those components of the protocol that could readily be adapted for local use. Work commenced during mid 2012.

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    Nutrient (phosphorus) loading limits (TMAPLs) for South African Dams

    Modelling of the nutrient (phosphorus) loading and responses of a suite of 30 South African dams was completed during April 2007. This project identified the nutrient loading thresholds at which these dams become impaired, or are at risk of becoming so, by noxious algae. In so doing the work will set Target Mean Annual Phosphorus Loads (TMAPLs) as provisional guidelines for setting rehabilitation (load reduction) or protection (threshold loads) phosphorus loading limits. This project builds on the NEAP (Nutrient Enrichment Assessment Protocol) previously developed for the Water Research Commission.

    South Africa is almost totally-reliant on storage of water in dams for water supply. In many cases, a large proportion of the flows to these dams is comprised of polluted stormwater runoff, agricultural return flows and wastewater effluents from urban developments. These return flows are characterized, in the main, by elevated concentrations of phosphorus. Ideally, the management (reduction/prevention) of eutrophication focuses on phosphorus attenuation. However, in South Africa, phosphorus elimination from wastewater and other effluents is not targeted as a priority. With eutrophication as the cause, the most common symptom is the increasing development of cyanobacterial aggregations, with the associated risk of cyanotoxin production. Cyanotoxins are notoriously difficult and costly to remove from raw potable waters.

    This project categorized a suite of SA dams in terms of:

    1. Their current trophic status.
    2. The current matrix (mix) of phosphorus sources contributing to the total annual loading of this element into each dam.
    3. Setting maximum acceptable loading limits for each dam.
    4. Identifying, from the landuse profiles, where effective nutrient attenuation practices should be focused.

    The findings of this study are being used in the TMDL feasibility study, see Total Maximum Daily Load (TMDLs) Feasibility Study.

    Download TMAPL Report

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    Elucidation of Food Web Interactions in South African Reservoirs using Stable Isotopes

    This two-year project evolved from the fishery biomanipulation study and entailed a detailed examination of the aquatic foodweb in Rietvlei Dam, Pretoria. The findings of the work, completed in 2012, confirmed that the previously proposed concept of top-down fishery management was indeed in applicable for South African reservoirs. see also KNP project

    Download Rietvlei SIA Report

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    Use of Stable Isotopes to Investigate Crocodile Deaths in the Kruger National Park

    In parallel with the SIA work being undertaken at Rietvlei, DHEC was appointed to undertake an assessment of the foodweb structure in the Olifants River between Phalaborwa and Massingir Dam in Mozambique.

    Download KNP SIA Report

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    The Possibility of Fishery-based Foodweb Manipulation for the Restoration and Management of Enriched South African Dams

    Recent work by DHEC and its associates mirrors overseas studies that have illustrated the potential for impoundment restoration possible via restructuring of imbalance fishery assemblages. Joint investigations undertaken at Hartbeespoort Dam demonstrated the possibility for sustainable, commercially-viable rehabilitation. Based on the findings of the Hartbeespoort Dam study this work will now be extended to a suite of 9 dams located in the Gauteng and North-West Provinces.

    The aims of this study were to:

    1. Determine the fish assemblages at a suite of impacted and control dams located in the same eco-region, coupled with the identification of trophic state and eutrophication impact assessment.
    2. Determine harvesting requirements to reset the fishery to a desired assemblage.
    3. Determine harvesting requirements to sustain the desired assemblage.
    4. Collect data on specific abiotic and biotic components (phytoplankton and zooplankton assemblage).
    5. Compare and contrast commonalities of ecosystem response and degree of system specificity.
    6. Assess, in broad terms, economic and financial implications of the recommended approach.
    7. Identify constraints to the proposed rehabilitation methodology.
    8. Evaluate the findings in terms of the potential of this approach as a method for impoundment rehabilitation, as well as for commercial opportunities.

    The project was completed in 2010. During the project it became clear that the proposed concept of top-down fishery management was unlikely to be successful in South African reservoirs. This was subsequently confirmed to be the case, see Elucidation of food web interactions in South African Reservoirs using Stable Isotopes.

    Download Report

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    Diatoms in Biomonitoring (Phase III)

    This pivotal project, undertaken in association with Dr Jonathan Taylor of North West University (Potchefstroom Campus) is probably the most exciting development in river and wetland biomonitoring in South Africa. Phases I and II of this work, phases that evaluated the potential and need for this approach, as well as developing a comprehensive toolbox of assessment protocols, have been completed and are available as various reports and DVD-based products. Phase III brought the use of diatoms into the formal biomonitoring arena, enabling the use of diatoms together with the vegetation, invertebrate and fish-based assessment protocols of the Ecostatus approach.

    In addition to Phase III of the river and stream orientated work was the development of a Diatom Index for use in the assessment of wetland health.

    The Phase III study was an extension of two earlier phases of the development of a diatom-based biomonitoring toolkit. The National Water Act (NWA) ensures the protection of water resources, and therefore methods are needed to identify and categorize the health of aquatic systems. The Phase III output has now been integrated into the River Health Program (NAEHMP). The Diatom Assessment Protocol (DAP) as a biomonitoring tool can be used to test the water quality of various waterways, including urban canals. The Phase III study also derived and calibrated a Diatom Index relevant to South African conditions, the South African Diatom Index (SADI). The SADI is now also available as part of the OMNIDIA software package of diatom indices.

    Phase III also saw the taxonomic key that was developed in Phase II expanded and made available as freeware via the LUCID website.

    Download SADI Report

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    Development of a diatom-based condition index for South African wetlands

    DHEC, in association with North-West University, was awarded a consultancy to develop a provisional diatom-based index for wetland environments. This project was completed in 2011.

    Diatom Index for Wetland Health Report

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    Pan-african diatom (Surirella sp.) project

    DHEC was awarded the South African component of an international project, funded by the Mellon Foundation, to compile a photomicrographic record of African specimens of the diatom genus Surirella (Surirellaceae). This project was led by the National Botanic Garden of Belgium and South Africa (DHEC together with NWU) and the Botanical Museum of Berlin.

    Download publication

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    Development of a diatom-based assessment protocol for South African rivers and streams

    Phases II and III of this project has been completed and a suite of tools are now available from the Water Research Commission website at

    SA Diatom Key

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    Development of a low-cost technology for microhabitat temperature monitoring in South African rivers

    One of biggest limitations to environmental flow planning is the lack of continuously-recorded temperature data. This projects aims to provide an inexpensive option to address this need.

    This project, undertaken in association with UKZN, has been completed and has been highly successful in achieving the goals of developing a low-cost, low-maintenance temperature logging system, with associated hardware and software. An example of the raw data output from the logging devices is shown below. Initial trials are nearing completion and the results will be published shortly. It is envisaged that this pilot-scale testing will be followed by a second phase during which method refinement and scale-up for wider national use will be undertaken.

    This project has been expanded into a second phase that has seen the Version 1 units substantially upgraded. Parallel work has integrated conductivity measurement and temperature logging.

    Raw Data Output Example

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    Strategic Research and Management Plan for Toxic Algae in South Africa

    WRC Report TT277/06.

    Download Report

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    Guide to Eutrophication Assessments

    DHEC contributed to the preparation of "A Guide to Catchment-Scale Eutrophication Assessments for Rivers, Reservoirs and Lacustrine Wetlands", now available as WRC Technology Transfer Report TT352/08.

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    Toxic Algae in South Africa: Phase II Management Strategy

    DHEC was appointed as advisory and planning consultant to undertake the second phase of this work. In addition to addressing specific issues such as the risk associated with the possible occurrence of BMAA (beta methyl amino alanine) in South Africa, Phase II of this project will focus on the establishment of a South African Research Network for Algal Toxins (SARNAT) and the roll-out of industry (water utilities and irrigation boards) information and support networking. This will also parallel and incorporate South African input to the envisaged Phase II of the international, UNESCO-IHP funded CYANONET project.

    February 2007 saw the hosting in Somerset West of a Global Water Research Coalition's (GWRC) workshop of the algal toxin working group. A key outcome of this workshop has been the preparation of an internationally-relevant manual on cyanobacterial assessment and management, a product that was comnpleted in 2010.

    Download GWRC Manual

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    Nutrient Enrichment Assessment Protocol (NEAP)

    A web-based interactive tool for preliminary assessment of nutrient loading and management options.

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    Development of Best Practice Guidelines and Implementation Strategies for the Management of Eutrophication in South Africa

    A Department of Water Affairs Project led by Shands Consulting (Cape Town).

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    Development of a model to assess the costs associated with eutrophication

    A Water Research Commission Project led by Ground Truth Consulting (Pietermaritzburg).

    This work formed a sub-component of a larger, multi-disciplinary study. DHEC was tasked with identifying an appropriate First Order model that describes the nutrient (phosphorus) loading behaviour of the dams on the Vaal River (Grootdraai, Vaal, Bloemhof and the Barrage). This, together with other tasks allied to eutrophication, was completed during 2011.

    Download Costs of Eutrophication Report