How much water do we actually have in our rivers? This is critical to consider if we are to effectively manage our water resources to the benefit of people and the environment.
The Endangered Wildlife Trust’s (EWT) Cape Critical Rivers (CCR) project is striving to answer this question in the Koue Bokkeveld, the hub of the fruit farming industry in the water-stressed Western Cape Province, South Africa. The flora of the Koue Bokkeveld consists of mountain Fynbos at high altitudes and Karoo vegetation in the lower slopes with patches of Mountain Cypress. The Koue Bokkeveld falls within the Olifants/Doring system and the Doring River has its sources in this range, contributing substantially to the flow of the Olifants catchment area.
The Cape Critical Rivers team recently went with hydraulics engineer Martin Kleynhans and the Department of Water Affairs, to undertake topographical surveys of selected rivers. These were identified as National Freshwater Ecosystem Priority Areas. The surveys provide the baseline data for accurately calculating the volume and timing of flows in these rivers throughout the year. The surveys effectively mapped cross-sections of the rivers from the ’water’s point of view’.
This allowed the CCR team to digitally model how water would move through the channel, from the smallest trickle during the dry season, to the raging torrents that sweep through these systems during the stormy Cape winters. This information is critical for developing a better understanding of the current state of these rivers and their capacity to provide sufficient water to maintain ecosystem function and support the array of species which are dependent on this system, as well as provide water for agriculture and basic human needs. This will be the first time that accurate flow information will be available for these important rivers, and the successful completion of the river surveys was an important accomplishment for this project.