Climate Aspects

The climate in the Zambezi basin is influenced by the convergence of three different chain draughts: the southeast chain, the northeast monsoon chain and the northeast chain known as Congo's humid air mass. This convergence, which generally occurs in the area between November or March, influenced by ITCZ (Inter Tropical Convergence Zone), is frequently diffuse and it’s identified as low digging depression superficies, that sometimes gets worse, associating low pressure centre zones where ICTZ gets intense.

Generally, these superficies migrate slowly, but they also can remain at a standstill for long period of time. Frequently, they are originated in low pressure centre areas, in the south of Angola that enable the circulation of hot air masses from Congo to the North-East of Zambezi basin, where due to the intensification of convergence, can generate flooding in high proportions, sometimes featured by rainfall and thunder cycles for several days which can be followed by low or no rainfall at all.

In these circumstances, the annual rainfall is higher on the Northern part of the basin, especially on the territory of Congo, Zambia, Malawi and the northern part of Tete province, reaching normal maximum values of 1.400 mm, while on the southern part of the basin, especially on the territory of Zimbabwe and southern part of Tete province, reaches normal maximum values of around 500 mm.

On the sub-basin of Kafue the average annual rainfall varies between 850 and 1200 mm, on the Luangwa basin it varies between 900 and 1100 mm, on the basins of rivers originated in Zimbabwe (Messenguezi and anyame/Panhame rivers) directly affluent to the reservoir, it varies between 700 and 900 mm and on the basins of rivers originated in national territory (Mucanha/Muze, Vuzi, Luangua and Metamboa rivers on the North, and Daque river on the South) it varies between 1400 mm on the North and 600 mm on the South.

The climate is characterized as a climate that is modified by altitude in the whole basin on the North side of the river, on the stretches of upper and middle Zambezi, and dry, particularly of steppe, on the South side. The lower Zambezi is of a rainy tropical type, particularly of savanna.