The Sahel Risks And Vulnerabilites Influenced By The Ecosystem, Climate And Hydrology Flashcards
Background
Drylands regions in Africa suffer desertification
Extends west to east Africa across 10 different nations
2006 - UNEP and ICRAF on climate change and variability in the Sahel stated that ‘without urgent investment’, feeding the Sahel is ‘mission impossible’
Physical threats to Sahel
Increased periodic drought -limited moisture means that there is low productivity and biodiversity in the ecosystem. The soils cannot support the agriculture and can only grow special adapted xerophytes - irrigation is needed to manage side effects such as salinisation, contour stone barriers to minimise run-of, increased sediment capture and infiltration leading to groundwater recharge
Changes in rainfall pattern - amount, type and timing can impact availability
Winter rain - penetrates the soil, heavy rain erodes soils
Summer - light showers fall on hot surfaces and are soon lost to evapotranspiration. Could be managed by storage in wet periods with ‘planting pits’ and then planting more drought resistant GM crops
Exposure to high winds - scarce vegetation means winds are high in winter can remove moist air around plants and soil increasing evapotranspiration
Soil erosion increases and silt,clay and organic matter is removed from the surface layer leaving a sandy, infertile soil.- vegetation barriers of grass species form a barrier to wind and erosion.
Infertile soils - lack of vegetation, decomposition and accumulation of organic matter in soil land is cultivated - organic matter is lost
Erosion leaves a shallow, sandy soil with poor structure and water retention. ( planting pits, organic matter is planted in them to improve fertility, dig channels to improve water-holding capacity
Plant nitrogen fixing plants eg, acacia - regenerating vegetation and the integration of tree crops - ‘re-greening of the Sahel’
Changes in the albedo surface
Human threats to Sahel
Population growth = sub -Saharan Africa population was 920 million in 2014 ( expected to double in the next 35 years) alongside decreasing IMR and lagging decrease in fertility = growth rates of 2.5% and 4% in countries of the Sahel region. The population will grow behind feeding capacity - Malthus with an expected increase of 3-5 in temp by 2050 could mean a 50% fall in productivity in Sudan alone. This could be manages by informing people of the benefits of smaller families, increase contraception and raise the legal age of marriage
Increasing deforestation - ( secondary threat from point 1) for fuel wood is a direct consequence of population and settlement growth - wind and water erosion of soil and loss of organic matter, managed by agroforestry and afforestation programmes
Overgrazing and over cultivation - overuse of land to grow crops due to demand for more production. The soil does not have time to recover and leads to infertility and crop failure management = educating farmers to reduce land degradation, investment in irrigation, adopt drought resistant crops eg, extase in wheat
Land grabbing -increasily looking for land in Sudan, china, South Korea, displacing many indigenous farmers with no legal tenure or negotiation rights
Many migrate to towns as droughts intensity on marginal land - improve legal rights for farmers for land ownership
