2 Africa-Wide Trends in Development and Water …
23
– likely increases in mean annual precipitation over areas of central and eastern
Africa;
– consistent annual and seasonal drying over the northern African region (including
North of Morocco, Algeria, Libya, Egypt and Tunisia);
– a significant decrease over the northern basin of Tunisia in the median and 10th
and 90th percentiles of precipitation in winter and spring seasons, and
– rainfall in East Africa that is at variance with the observed rainfall pattern.
Climate projections show the possibility of increased flooding and drought
extremes. This has significant impacts on agricultural production in countries
the weather patterns of which are impacted by these systems. An increase in
the frequency of extreme events has implications for decisions about infrastructure,
often requiring larger, more engineered solutions that are more expensive and can
have negative environmental impact. Extreme flood, drought and disease events will
increase migration pressures on refugee settlements and urban informal areas as well
as fauna and flora survival.
The impact of climate change on streamflow must be considered in addition
to its impact on rainfall. The amount of rain in a river that is converted into actual
streamflow depends on a number of factors, including the vegetation in the catchment,
the level of land degradation, the nature of the soil, slope and temperature. In South
Africa, for example, only around 9% of rainfall ends up as river streamflow. The
IPCC predicts that across the continent, streamflow will change from −15% to +
5% by 2050. In southern Africa in particular, almost all countries will experience a
decrease in streamflow. Other areas are less reliably predictable: for example, there
is no clear understanding of how streamflow in the Nile will be affected by climate
change. Changes in streamflow are especially pertinent for sectors such as agriculture,
manufacturing and mining, because streamflow is often translated into blue water
that is dammed, piped and then irrigated or treated for domestic consumption or
industrial use. The extent of streamflow change is also impacted by development and
land use change in parallel with the catchment. For these reasons, management of
the nature and extent of agriculture, manufacturing, mining and other land use will
fundamentally change how much water is available for use.
Climate change and green water use in agriculture poses risks as well as
opportunities. Erosion is a particular risk to rain-fed agriculture in the presence
of climate change. In Egypt, climate change could reduce crop production by up
to 28% for soybeans and 11% for rice by 2050. A reduction of 20% in the annual
crop-growing period in semi-arid areas is projected by 2050. At the same time,
there may also be positive impacts on agriculture, such as the projected increase in
rainfall for some parts of tropical or eastern Africa (Niang et al. 2014). But coastal
zones and estuaries are at particular risk from sea level rise, changes in run off and
changing temperatures. A decrease in rainfall, for example, may significantly change
the distance to which saltwater penetrates upstream in a river. As a result, coastal
agriculture, including palm oil and coconut plantations in Benin and Cote d’Ivoire,
may be affected by inundation and soil salinization. In Kenya, a 1 m sea level rise
23
– likely increases in mean annual precipitation over areas of central and eastern
Africa;
– consistent annual and seasonal drying over the northern African region (including
North of Morocco, Algeria, Libya, Egypt and Tunisia);
– a significant decrease over the northern basin of Tunisia in the median and 10th
and 90th percentiles of precipitation in winter and spring seasons, and
– rainfall in East Africa that is at variance with the observed rainfall pattern.
Climate projections show the possibility of increased flooding and drought
extremes. This has significant impacts on agricultural production in countries
the weather patterns of which are impacted by these systems. An increase in
the frequency of extreme events has implications for decisions about infrastructure,
often requiring larger, more engineered solutions that are more expensive and can
have negative environmental impact. Extreme flood, drought and disease events will
increase migration pressures on refugee settlements and urban informal areas as well
as fauna and flora survival.
The impact of climate change on streamflow must be considered in addition
to its impact on rainfall. The amount of rain in a river that is converted into actual
streamflow depends on a number of factors, including the vegetation in the catchment,
the level of land degradation, the nature of the soil, slope and temperature. In South
Africa, for example, only around 9% of rainfall ends up as river streamflow. The
IPCC predicts that across the continent, streamflow will change from −15% to +
5% by 2050. In southern Africa in particular, almost all countries will experience a
decrease in streamflow. Other areas are less reliably predictable: for example, there
is no clear understanding of how streamflow in the Nile will be affected by climate
change. Changes in streamflow are especially pertinent for sectors such as agriculture,
manufacturing and mining, because streamflow is often translated into blue water
that is dammed, piped and then irrigated or treated for domestic consumption or
industrial use. The extent of streamflow change is also impacted by development and
land use change in parallel with the catchment. For these reasons, management of
the nature and extent of agriculture, manufacturing, mining and other land use will
fundamentally change how much water is available for use.
Climate change and green water use in agriculture poses risks as well as
opportunities. Erosion is a particular risk to rain-fed agriculture in the presence
of climate change. In Egypt, climate change could reduce crop production by up
to 28% for soybeans and 11% for rice by 2050. A reduction of 20% in the annual
crop-growing period in semi-arid areas is projected by 2050. At the same time,
there may also be positive impacts on agriculture, such as the projected increase in
rainfall for some parts of tropical or eastern Africa (Niang et al. 2014). But coastal
zones and estuaries are at particular risk from sea level rise, changes in run off and
changing temperatures. A decrease in rainfall, for example, may significantly change
the distance to which saltwater penetrates upstream in a river. As a result, coastal
agriculture, including palm oil and coconut plantations in Benin and Cote d’Ivoire,
may be affected by inundation and soil salinization. In Kenya, a 1 m sea level rise