Jackie King

Environmental Flows: Striking the Balance between Development and Resource Protection

Management of scarce water resources through the use of environmental flows, particularly in developing countries in data-poor arid areas, raises many scientific challenges. These include transforming hydrological data into an ecologically relevant format, providing quantified predictions of river responses to flow change, describing the impacts of river change on common-property users of the rivers, providing the information in a format that decision makers can use, and guiding monitoring and adaptive management. Each of these challenges emerged in South Africa during the last two decades, when rivers and other aquatic ecosystems were enhanced in stature from having no rights to their own water to being one of only two sectors with a right to water; the other sector is for basic human needs. This paper outlines the challenges, how they are being addressed in South Africa, and perceptions of what remains to be done.

Particulate organic matter in a mountain stream in the south-western Cape, South Africa

The quality and quantity of allochthonous inputs and of benthic organic matter were investigated in a second-order, perennial mountain stream in the south-west Cape, South Africa, between April 1983 and January 1986. Although the endemic, riparian vegetation is sclerophyllous, low and evergreen, inputs of allochthonous detritus to the stream (434 to 500 g m−2y−1) were similar to those recorded for riparian communities worldwide, as were calorific values of these inputs (9548 to 10 032 KJ m−2y−1). Leaf fall of the riparian vegetation is seasonal, occurring in spring (November) as discharge decreases, resulting in retention of benthic organic matter (BOM) on the stream bed during summer and early autumn (maximum 224 g m−2). Early winter rains (May) scoured the stream almost clean of benthic detritus (winter minimum 8 g m−2). Therefore, BOM was predictably plentiful for about half of each year and predictably scarce for the other half. Coarse BOM (CBOM) and fine BOM (FBOM) constituted 46–64% of BOM standing stock, ultra-fine BOM (UBOM) 16–33% and leaf packs 13–24%. The mean annual calorific value of total BOM standing stock was 1709 KJ m−2. Both standing stocks and total calorific values of BOM were lower than those reported for streams in other biogeographical regions. Values of C:N ratios decreased with decrease in BOM particle size (CBOM 27–100; FBOM 25–27; UBOM 13–19) with no seasonal trends. The stream is erosive with a poor ability to retain organic detritus. Its character appears to be dictated by abiotic factors, the most important of which is winter spates.

The distribution of invertebrate communities in a small South African river

Monthly samples of macroinvertebrates were collected from the stony-bed and marginal-vegetation habitats of a small river in the south western Cape Province, South Africa. Cluster analyses of the samples revealed assemblages of invertebrates (here referred to as ‘communities’) with clear spatial and temporal distribution patterns in the muer. The species composition of the communities, and their distribution, are described. The relation of the macroinvertebrate distribution to changes in the physico-chemical environment was investigated using stepwise multiple discriminant analysis. The results indicated a strong correlation between the two.

Spawning behaviour and early development of the Clanwilliam yellowfish (Barbus capensis; Cyprinidae), linked to experimental dam releases in the Olifants River, South Africa

This paper describes an investigation of how experimental releases of pulses of high flow from Clanwilliam Dam (Olifants River, South Africa) affect spawning of the Clanwilliam yellowfish, Barbus capensis. This species is endemic to the Olifants River system and is listed as rare in the Red Data Book of fishes for South Africa. Spawning sites are described, as is the spawning behaviour of B. capensis after specific experimental pulses released during the suspected spawning season of the species. Spawning and the developmental stages of embryos, free embryos, and larval B. capensis were studied using direct observations, video recordings, and microscopic examination of live embryos. B. capensis was found to be a repeat-spawner over several days as well as a multiple-spawner throughout the 4 month reproductive season. At present, spawning of B. capensis occurs down-stream of the dam sporadically (and possibly with limited recruitment), concurrent with releases of water for irrigation purposes. Experimental pulses appeared to trigger an increase in spawning activity, as an abundance of larvae was found down-stream 2 months later. It is suggested that a water-release strategy from Clanwilliam Dam could be designed to increase the number of B. capensis in the Olifants River.

Modifying dam operating rules to deliver environmental flows: experiences from southern Africa

Provision for environmental flows (EFs) in water use and water-resource developments has been legislated in several southern and eastern African countries. While much of the focus has been on the assessment of EFs for new water-resource developments, some attention has been paid to the possibilities of modifying the operation of existing infrastructure to deliver EFs. This paper summarizes research done to support the re-operation of the Katse Dam in Lesotho, the Clanwilliam and Kogelberg Dams in South Africa, the Cahora Bassa Dam in Mozambique and the Nyumba ya Munga Dam in Tanzania in ways that would reduce their downstream impacts. For each, the original and suggested new operating rules are presented, and the reasons for the suggested changes are summarized. The negotiation and decision-making processes relevant to each dam are also discussed, and some of the challenges faced at two of the dams (Katse and Kogelberg), where revised operating rules have been implemented, are reviewed.

Introduction: Dams, ecosystems and livelihoods

Today, in a world of rapidly growing human numbers, wise management of freshwater is increasingly important. We face a major challenge of how to support national development goals, meet food needs, safeguard the livelihoods of rural people, and simultaneously protect an increasingly degraded environment. Against this background, the Challenge Program for Water and Food 1 is an ambitious research and capacity building program that aims to significantly influence the use and management of water, particularly in agriculture. One part of this program is a project, presently underway, entitled Improved planning of large dam operation: using decision support systems to optimize livelihood benefits, safeguard health and protect the environment. The aim of the project is to conduct research to assess how decision support systems can improve the planning, design and operation of large dams in order to ensure sustainable use of river resources and improve equity in the distribution of benefits. The project partners are: Addis Ababa University, Ethiopia, the Ministry of Water Resources, Ethiopia, Southern Waters, South Africa and the InternationalWater Management Institute.As part of its activities, the project organised an international conference in Nazaret, Ethiopia in January 2006, which focused on dams and decision support systems. The papers in this special issue emanate from the conference. No-one can deny the benefits that large dams have brought. Most of the developed world benefits in some way from irrigated agriculture, hydropower generation, assured water supply, flood control and/or improved navigation, and these benefits are increasingly sought and being achieved by developing countries. Nevertheless, history has taught us that large dams create costs as well as benefits and their continued presence and, particularly, future expansion remains controversial. These twin aspects of dams are reported in detail in the many documents written for and by the World Commission on Dams and its successor, the UNEP Dams and Development Project. Too often in the past large dams have brought fewer benefits than envisaged and have had unforeseen and often highly significant environmental and social costs. Only within the last two decades, for instance, has it been widely recognised that the human impacts of dams stretch from upstream, where people

Achieving an environmentally sustainable outcome for the Gulpur hydropower project in the Poonch River Mahaseer National Park, Pakistan

An holistic environmental flows (EFlows) assessment, undertaken as part of an environmental and social impact assessment (ESIA), led to improved planning and design of the Gulpur hydropower project (HPP) on the Poonch River, Mahaseer National Park, Pakistan. The park was declared a conservation area primarily because of its two globally threatened fish species, the endangered Mahaseer (Tor putitora) and critically endangered Kashmir Catfish (Glyptothorax kashimirensis). These triggered critical habitat thresholds for the funders, requiring special biodiversity protection measures. Despite the river’s conservation status, these two species are under threat of extinction from unsustainable harvesting and catchment practices, notably non-selective fishing practices and sand and gravel mining in the river bed. The EFlows study analysed various permutations of flow releases from the proposed dam, operational regimes and catchment management options. The need to contain existing adverse impacts on the threatened fish and river ecosystem, combined with the results of the assessment, influenced the planned turbine design, weir location and operational regime of the project. Additional management measures to enhance the protection status of the park and its fish to achieve a biodiversity net gain outcome were developed with conservation management stakeholders and communities. These measures were incorporated into a biodiversity action plan, which was approved by Pakistan’s regulatory authorities and paved the way for approval of the project financing by international lenders. The project represents a valuable case study on mechanisms for achieving ecologically sustainable HPPs.