The impact of climate change on vulnerable water resources in southern Africa
The southern African region consists of four major river basins including the Zambezi River Basin, the Orange River Basin, the Okavango River Basin and the Limpopo River Basin. The annual precipitation ranges from 100 mm in the west to 1 500 mm in the northern and eastern parts. On the other hand evapotranspiration exceeds average annual rainfall in most parts of the region (Table 1). Hence renewable freshwater estimated at 650 billion m3 is unevenly distributed over rivers, lakes and groundwater in the region. That means under natural conditions water is unevenly distributed throughout the region.
The land cover largely mirrors the climate, with grassland and open shrub land in the west and southwest, savannah in the southeast and evergreen broadleaf forests in the north.
The economies of the southern African countries are highly dependent on the natural resources (i.e. on the ecosystem goods and services such as tourism, agriculture and mining). Some sub-regions such as Limpopo are characterized by land degradation and high population growth as well as urbanisation. Other challenges that render these countries vulnerable to climate change and climate variability include lack of proper infrastructure and inadequate storage, poor institutional capacity, population growth, paucity of climate information, saline water intrusion along coastal areas, water pollution and inadequate early warning or preparedness systems. Vulnerability is considered to be a function of exposure, sensitivity and adaptive capacity, with the latter, in turn, dependent on wealth, technology, education, information, skills, and infrastructure, access to resources and stability as well as management capabilities.
Chris Moseki, Research Manager at the Water Research Commission says “Model projections show that changes in temperature and rainfall are most likely to have significant impact on water resources in southern Africa. Climate models projections show a likely increase in the number of people who could experience water stress by 2055 in northern and southern Africa”.
The development sector information was overlaid with the projected climate changes for 2050 according to the latest Intergovernmental Panel on Climate Change Fourth Assessment Report. Changes in climate were characterized in terms of change in mean seasonal rainfall (i.e. summer versus winter rains) and changes in mean summer and winter temperature.
According to Moseki resilience building to enhance adaptive capacity to climate change impacts is necessary as the southern African region is one of the most vulnerable. It may be best to start with things that each country can do now such as governance and institutional reform, monitoring (climate information), focus on improved livelihoods through sustainable development and protection of ecosystem goods and services.
Contact: Mr Chris Moseki
Research Manager: Water Resource Management
Email: Chrism@wrc.org.za or cell 083 452 6964