Zambezi River Basin
last updated: 7 April 2021 by Raphael (rapp@env.dtu.dk)
The Zambezi River Basin extends over 1.4 million square kilometers over eight countries: Angola, Botswana, Malawi, Mozambique, Namibia, Tanzania, Zambia, and Zimbabwe. The population was estimated around 40 million people in 2015, and is expected to reach 51 million in 2025 and 70 million in 2050.
Average precipitation in the river basin is 950 mm, with important variation as the northern and eastern parts receive approximately twice as much rain as the southern part. Average net runoff is around 110 000 Mm³ per year (Beilfuss, 2012). The main consumptive uses of water are the large man-made reservoirs (Kariba and Cahora Bassa) with around 8 000 Mm³ per year; irrigation consumptive use was around 3000 Mm³ per year in 2010, while domestic and industrial consumption, mainly from coal mines, represent a minor share with around 800 Mm³ per year (World Bank, 2010). The Zambezi River supports vital ecosystems, including the Kafue Flats and the Barotse Plain in Zambia, the Mana Pools in Zambia and Zimbabwe, and the Zambezi Delta in Mozambique.
The main source of energy is biomass, covering about 80% of the energy demand. Most of the population does not have access to electricity: access rates vary from 12% in Zambia to 40% in Zimbabwe (SADC et al., 2015). The countries in the river basin are member of the South African Power Pool (SAPP). Malawi, Tanzania and Angola are not yet fully connected but projects are under development (SAPP, 2018). While the power pool is dominated by South Africa (80% of power demand) and coal-fired power plants (77% of production), in the Zambezi River Basin, hydropower is the main source of electricity production (World Bank, 2010). Agriculture and land Most of the area is covered by bush (75%), cropland represents 13% of the area. Only 5% of the cultivated area is irrigated (SADC et al., 2015), with sugar cane being the most irrigated crop representing 33% of irrigated area (FAO, 2018), while the most common cultivated crop is maize, covering 43% of cultivated area. A majority of the agriculture is smallholder farming, and average yields are far below standard yields (World Bank, 2010). Informal charcoal production for use as cooking fuel, leads to progressive deforestation and land erosion (SADC et al., 2015).
Gross Domestic Product (GDP) per capita ranges from about 1000 $ in Malawi to 18 000 $ in Botswana. While services represent the biggest share of GDP in all countries, agriculture is still a major contributor in Tanzania, Malawi and Mozambique and is the main labor occupation in all countries (CIA, 2020). Coal, copper, and gold extraction represent an important part of GDP in Angola, Botswana, and Zambia. For example in Zambia, 50% of the electricity consumption is from the mining industry (SADC et al., 2015).
Under climate change the annual runoff could vary between -50% to +30% (Cervigni et al., 2015). Carbon taxes might be introduced in the power system (IRENA, 2013), while the capital costs of renewable energies are predicted to decrease (IRENA, 2013). As a result, about 80% of new power investments could be renewable energy investment. Average crop yields are expected to double by 2050 due to improved agricultural practices (OECD and FAO, 2017). With population increase and economic development, crop demand is expected to increase by 60% from 2010 to 2030 (IFPRI, 2017), while energy demand could increase by 90% in the same period (SAPP, 2015).
To accommodate the growing demands in the Zambezi, hydropower and irrigation development plans (World Bank, 2010) contain 15 hydropower projects totaling 7.2 GW adding to the existing 5 GW, and 336 000 ha of irrigation projects that could triple current area under irrigation.