15 Impacts of Climate Change on Water Resources …
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in the savannah in the 2050s compared to the present climate, especially in Ghana
(Schroth et al. 2016). Drier-than-average years could become more frequent in West
Africa than they are now, possibly increasing the risk of drought (Abiodun et al.
2013). Under present climatic conditions, it is generally assumed that drought is
a greater threat to cocoa than is high temperature in West Africa (Carr and Lockwood 2011). Drought has affected cocoa yields regularly in West Africa, particularly
during the severe El Niño years of the 1980s (Ruf 2011). The only practical way
of protecting cocoa trees from high temperatures is through overhead shade from
appropriately selected, spaced and managed companion trees and selected crops
(especially bananas and plantains) co-located on the cocoa farm so that shading can
reduce coca leaf temperatures by up to 4 °C (Almeida and Valle 2007). Adequate
ventilation is also an important complement because it can reduce fungal disease on
cocoa plantations (Zhang and Motilal 2016).
Because of drought periods and erratic rainfalls without effective water management to promote crop production, the Volta Basin countries can no longer rely on
rain-fed agriculture to feed their rapidly increasing populations. Mitigation practices
may include irrigation and water harvesting technologies to enhance agricultural
productivity. This is especially applicable to Northern Ghana and Burkina Faso,
where the rainy season lasts for only four to five months. Adaptive strategies would
therefore include continued efforts to produce faster-growing rain-fed crop cultivars, mainly corn and sorghum, as well as better storage of surface run-off in small
reservoirs during the wet season for use during the dry season. The use of (shallow)
groundwater during the dry season is a highly complementary adaptation strategy
(van de Giesen et al., 2008) for building the resilience of crop production systems
against climate change. Other such strategies in the Volta Basin include conservation agriculture, alternate wetting and drying approach (AWD) for rice production,
agroforestry, “zaï” water conservation technology and the development of varieties
of cultivars that are resilient to higher temperatures, drought, pest, weeds, salinity,
flooding, etc., with a greater emphasis on new varieties that can withstand multiple
stresses.
Trees in or near agricultural fields reduce the vulnerability of cropping systems to
climate variations, so the introduction of trees in agriculture, such as in agroforestry
and silvopastoralist systems, is considered to be an effective adaptation strategy.
Tree roots reach into deep soil for water and nutrients, which benefits crops during
droughts. Trees improve fertility and protect soils from erosion by increasing soil
organic matter, porosity, infiltration and soil cover (Verchot et al. 2007). Nitrogenfixing trees contribute to the resilience to droughts of crops due to improvements
in soil nutrients and water infiltration – in, for example, Ghana and Burkina Faso
(Garrity et al. 2010). Studies of agroforestry systems highlight the trade-offs of trees
between increasing soil protection and reducing the light available to crops under
the canopies. In agroforestry, tree ecosystems may contribute differently to the adaptation of crops to climate change depending on climate scenarios and production
systems (Verchot et al. 2007). Within the Volta Basin, farmers mostly maintain agroforestry parkland systems, characterized by the deliberate retention on farmlands of
economically valuable and multipurpose trees such as Shea (Vitellaria paradoxa),
345
in the savannah in the 2050s compared to the present climate, especially in Ghana
(Schroth et al. 2016). Drier-than-average years could become more frequent in West
Africa than they are now, possibly increasing the risk of drought (Abiodun et al.
2013). Under present climatic conditions, it is generally assumed that drought is
a greater threat to cocoa than is high temperature in West Africa (Carr and Lockwood 2011). Drought has affected cocoa yields regularly in West Africa, particularly
during the severe El Niño years of the 1980s (Ruf 2011). The only practical way
of protecting cocoa trees from high temperatures is through overhead shade from
appropriately selected, spaced and managed companion trees and selected crops
(especially bananas and plantains) co-located on the cocoa farm so that shading can
reduce coca leaf temperatures by up to 4 °C (Almeida and Valle 2007). Adequate
ventilation is also an important complement because it can reduce fungal disease on
cocoa plantations (Zhang and Motilal 2016).
Because of drought periods and erratic rainfalls without effective water management to promote crop production, the Volta Basin countries can no longer rely on
rain-fed agriculture to feed their rapidly increasing populations. Mitigation practices
may include irrigation and water harvesting technologies to enhance agricultural
productivity. This is especially applicable to Northern Ghana and Burkina Faso,
where the rainy season lasts for only four to five months. Adaptive strategies would
therefore include continued efforts to produce faster-growing rain-fed crop cultivars, mainly corn and sorghum, as well as better storage of surface run-off in small
reservoirs during the wet season for use during the dry season. The use of (shallow)
groundwater during the dry season is a highly complementary adaptation strategy
(van de Giesen et al., 2008) for building the resilience of crop production systems
against climate change. Other such strategies in the Volta Basin include conservation agriculture, alternate wetting and drying approach (AWD) for rice production,
agroforestry, “zaï” water conservation technology and the development of varieties
of cultivars that are resilient to higher temperatures, drought, pest, weeds, salinity,
flooding, etc., with a greater emphasis on new varieties that can withstand multiple
stresses.
Trees in or near agricultural fields reduce the vulnerability of cropping systems to
climate variations, so the introduction of trees in agriculture, such as in agroforestry
and silvopastoralist systems, is considered to be an effective adaptation strategy.
Tree roots reach into deep soil for water and nutrients, which benefits crops during
droughts. Trees improve fertility and protect soils from erosion by increasing soil
organic matter, porosity, infiltration and soil cover (Verchot et al. 2007). Nitrogenfixing trees contribute to the resilience to droughts of crops due to improvements
in soil nutrients and water infiltration – in, for example, Ghana and Burkina Faso
(Garrity et al. 2010). Studies of agroforestry systems highlight the trade-offs of trees
between increasing soil protection and reducing the light available to crops under
the canopies. In agroforestry, tree ecosystems may contribute differently to the adaptation of crops to climate change depending on climate scenarios and production
systems (Verchot et al. 2007). Within the Volta Basin, farmers mostly maintain agroforestry parkland systems, characterized by the deliberate retention on farmlands of
economically valuable and multipurpose trees such as Shea (Vitellaria paradoxa),