90
S. Kusangaya et al.
According to Tshimanga (2012) river catchments with considerable total renewable water resources will play an important role in regional cooperation. About
seventy percent (70%) of surface water resources are in 15 transboundary river catchments (Fig. 1 and Table 1). Five SADC countries have water resource dependency
ratios of over 50%, that is, they rely on water generated outside their borders to supply
more than half of their total water requirements (Kistin et al. 2009; Malzbender et al.
2009). Kusangaya et al. (2017) summarised the water resources characteristics for
the Southern African region as follows:
1. About 70% of the available freshwater resources are from shared water resources.
2. Water is unevenly distributed spatially and temporally with abundant water
resources in the northern and eastern areas while the south western areas are
predominantly dry.
3. Most of the rivers have highly seasonal flows with surplus water during the rainy
season, and water deficit during the dry season.
4. Surface water sources are sensitive to inter-annual variation of rainfall, and
frequent drought periods, most of the arid and semi-arid parts experience dire
shortages of water.
5. There is a very low conversion rate of rainfall to runoff with most parts having
runoff coefficients less than 0.15. Most of the available runoff especially in South
Africa is generated from the few mountainous catchments.
Most parts of southern Africa lying south of the 17°S latitude receive less than
650 mm/yr of rainfall with the exception of areas of high altitudes like hilly and
mountainous areas. North of this latitude, the average rainfall varies mostly from
900–2000 mm/yr. Mean annual runoff is generally less than 50 mm/yr south of
the 17°S latitude. For most parts of southern Africa, the runoff is less than 10%
of the rainfall with the rest evaporating from water bodies, soils and plants. Most
parts of the SADC region have low potential for groundwater development. Intergranual porous aquifers cover 45% of this region, while 33% has low permeability
aquifers, 19% fissured aquifers and 3% karst formations (Pietersen and Beekman
2016. Groundwater is important for rural water supply. Pietersen and Beekman
(2016) estimated that groundwater constituted 13% of the available water resources
in SADC or 7199 m
3 /yr/capita.
3 Climate Change in Southern Africa
3.1 Temperature Changes in Southern Africa
Analysis of both remote sensed and observed temperature data in southern Africa
shows that the region has experienced a warming trend (Hughes and Balling 1996;
Unganai 1996; Kruger and Shongwe 2004; Warburton and Schulze (2005a); New
et al. 2006; Manatsa and Reason 2016) (Table 1). Kruger and Sekele (2013) found
S. Kusangaya et al.
According to Tshimanga (2012) river catchments with considerable total renewable water resources will play an important role in regional cooperation. About
seventy percent (70%) of surface water resources are in 15 transboundary river catchments (Fig. 1 and Table 1). Five SADC countries have water resource dependency
ratios of over 50%, that is, they rely on water generated outside their borders to supply
more than half of their total water requirements (Kistin et al. 2009; Malzbender et al.
2009). Kusangaya et al. (2017) summarised the water resources characteristics for
the Southern African region as follows:
1. About 70% of the available freshwater resources are from shared water resources.
2. Water is unevenly distributed spatially and temporally with abundant water
resources in the northern and eastern areas while the south western areas are
predominantly dry.
3. Most of the rivers have highly seasonal flows with surplus water during the rainy
season, and water deficit during the dry season.
4. Surface water sources are sensitive to inter-annual variation of rainfall, and
frequent drought periods, most of the arid and semi-arid parts experience dire
shortages of water.
5. There is a very low conversion rate of rainfall to runoff with most parts having
runoff coefficients less than 0.15. Most of the available runoff especially in South
Africa is generated from the few mountainous catchments.
Most parts of southern Africa lying south of the 17°S latitude receive less than
650 mm/yr of rainfall with the exception of areas of high altitudes like hilly and
mountainous areas. North of this latitude, the average rainfall varies mostly from
900–2000 mm/yr. Mean annual runoff is generally less than 50 mm/yr south of
the 17°S latitude. For most parts of southern Africa, the runoff is less than 10%
of the rainfall with the rest evaporating from water bodies, soils and plants. Most
parts of the SADC region have low potential for groundwater development. Intergranual porous aquifers cover 45% of this region, while 33% has low permeability
aquifers, 19% fissured aquifers and 3% karst formations (Pietersen and Beekman
2016. Groundwater is important for rural water supply. Pietersen and Beekman
(2016) estimated that groundwater constituted 13% of the available water resources
in SADC or 7199 m
3 /yr/capita.
3 Climate Change in Southern Africa
3.1 Temperature Changes in Southern Africa
Analysis of both remote sensed and observed temperature data in southern Africa
shows that the region has experienced a warming trend (Hughes and Balling 1996;
Unganai 1996; Kruger and Shongwe 2004; Warburton and Schulze (2005a); New
et al. 2006; Manatsa and Reason 2016) (Table 1). Kruger and Sekele (2013) found