The impact of global climate change on the runoff and ecological sustainability of the Breede River

The Breede River catchment in the South Western Cape is already under pressure for its water resources due to its supporting a variety of different land uses. The predominant land use in this catchment is agriculture, which demands the majority of river water for irrigation. The Department of Water Affairs and Forestry are currently investigating the future demand for water from the river, in this respect it is important to know what effect climate change will have on the change in river flow. Self Organising Maps (SOMs) are used to identify changes in the circulation systems contributing to the rainfall of the region and from this the potential change is assessed for the Breede River flow under future climate change. It is assessed that the runoff in the Breede River is expected to change under all the models of ECHAM4, CSIRO and HadAM. The magnitude of this alteration is calculated by using the change in the SOM node frequencies between the present and the future data. This is then subtracted from the present runoff data supplied by DWAF. A source of runoff decrease in the future is agricultural irrigation. The increase in irrigation under climate change is determined by inserting future climate data into an agricultural model. Once the increased amount of water used in irrigation is determined, it is subtracted from the projected future runoff. From this it is determined whether the river will be ecologically sustainable under climate change.

Grantor dc:publisher.institution

Department of Environmental and Geographical Science

Year dc:date.issued

2004

Author dc:creator

• Steynor, Anna C

Advisors dc:contributor.advisor

• Hewitson, Bruce
• Archer, Emma

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/6754

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/6754