Source to Sea Programme
The Cape Critical Rivers Project is an award-winning conservation, research and management initiative that bridges biodiversity conservation with water resource management in the Cape Floristic Region of the Western Cape, South Africa. Using novel, evidence-based approaches it builds climate change resilience and water resource security in core freshwater biodiversity and water supply areas within the region. It is coordinated by the Endangered Wildlife Trust and the Freshwater Research Centre with project partners, CapeNature, the Department of Environment and Nature Conservation Northern Cape and Aurecon Engineering.
The Cape Critical Rivers draws on a wide spectrum of skills, expertise and experience in the field of aquatic ecosystem science, management and conservation. It is uniquely placed to promote the wise use of water-linked ecosystems and to support local authorities in developing innovative cost-effective management interventions that have high water resource and biodiversity protection returns in a region with an exceptionally high water demand.
The Cape Floristic Region is a 90 000 km2 biodiversity hotspot on the south-western edge of the African continent in South Africa. It is widely celebrated for its outstanding natural beauty, biological diversity and local species endemism. It also circumscribes a number of mountain catchments with some of the highest water yield areas in the country.
A Clanwilliam Yellowfish in the Driehoeks River, Cederberg (B.PAXTON)
These Strategic Water Source Areas are of singular importance for supplying water to downstream urban, agricultural and industrial areas. They also correspond to no fewer than seven UNESCO designated World Heritage Site clusters including the Cederberg, Groot Winterhoek and Boosmansbos-Grootvadersbos Wilderness Areas, the Boland and Table Mountain complexes and the Swartberg.
The rivers that drain out of these areas provide critical refuges for many endemic fish and invertebrate species. However, unsustainable water abstraction, habitat destruction, pollution and invasive alien fish species have led to dramatic declines in these unique species over the past fifty years or so. As a result, most species are highly threatened; including charismatic angling species like the Clanwilliam Yellowfish, the endangered Breede River Whitefish and Clanwilliam Sawfin, together with an array of striking redfin minnows like the endangered Fiery Redfin and the critically endangered Twee River and Breede River Redfins.
Current Core Focal Areas of the Cape Critical Rivers in Cape Floristic Region
The Cape Critical Rivers is providing a range of water users, governing bodies and local communities with up-to-date data on the status of river systems using a network of monitoring stations in the core focal areas. In so doing, we aim to encourage solutions that balance economic imperatives and human needs, at the same time as protecting species and supporting ecosystem services. We aim to expand this model to other catchments in the Cape Floristic Region, as well as developing it as a template for applying to other regions in the country.
Doring River - Oorlogskloof Sandfish Conservation Project
Monitoring populations of the Critically Endangered Clanwilliam Sandfish on the Doring River (B.PAXTON)
The Cape Critical Rivers team also developed a methodology for assessing the invasion risk profile of dams within the drainage area of the Oorlogskloof Nature Reserve. This has enabled local conservation authorities to prioritize conservation actions and thereby limit the spread of alien, or other fish species to the system.
A rare sight – a juvenile Clanwilliam sandfish from the Biedouw River (B.PAXTON)
On the basis of the above assessment, a Memorandum of Understanding (MoU) has been drafted between the landowners that have high-risk dams on their properties and CapeNature, which will allow clearing of the dams by means of rotenone once the legal framework for such an intervention is in place. A plan of operation for use of rotenone to eradicate alien fishes from dams in the catchment, the Bokkeveld Plateau and Nieuwoudtville has been drafted by the Department of Environment and Nature Conservation, Northern Cape and CapeNature. Primarily as a result of basin-wide fish surveys of the Doring River and its tributaries, implemented by the Cape Critical Rivers and in partnership with CapeNature, additional sandfish spawning sites have been identified on the Biedouw River where conservation interventions are urgently required to restore critical habitats and river flow in these areas.
Kouebokkeveld Ecological Reserve Assessment and Monitoring
The endangered Clanwilliam sawfin – unique to the rivers of the Cederberg and Kouebokkeveld (B.PAXTON)
In addition to the Department of Water and Sanitation’s gauging weirs, the Cape Critical Rivers team has installed another two flow monitoring sites in the catchment bringing to four, the total number of sites where Ecological Reserve is being monitored. The team will be integrating the tools and protocols developed during the course of the project into Strategic Adaptive Management plans (SAMs) which will eventually feed into existing management systems at local and regional scales.
Automatic water level loggers are being used to continuously monitor water levels in catchments throughout the Cape Floristic Region (B.PAXTON)
We have also been working with a group of case study farmers in the Kouebokkeveld to investigate the use of the Fruitlook programme developed by the Department of Agriculture as an objective tool for monitoring and improving irrigation efficiency. Initial results indicate that there could be significant benefits for using this system to supplement current irrigation management practices.
Huis-Tradouw River Flow Restoration and Monitoring Project
Flow volumes at two locations in the catchment: at the mainstem of the Huis River and at the canal at the Donkergat weir offtake point, have been monitored continuously since May 2013. This data is being used to measure abstraction levels from the river and to estimate the quantity of water that can be re-allocated during the summer low-flow period for sustaining ecosystem processes.
Aurecon Engineering have designed a release mechanism for the Donkergat Weir which will enable ecological releases to be made. During the course of 2016/2017, the release valve will be installed and experimental releases will begin to determine what the effect will be on the town of Barrydale’s water security and on the downstream ecosystem. Using teams from CapeNature’s Grootvadersbosch Reserve, alien vegetation – notably Australian black wattle – will be cleared from the riparian zone of the upper Huis River which will improve water supply. We will also be partnering with CapeNature to monitor fish community composition, relative abundances, fish health and population size-structures on an annual basis, downstream of the Donkergat weir, to assess the effectiveness of ecological releases.
Estimating flow volumes in rivers using an electromagnetic current meter (B.PAXTON)
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