Most of the basin falls within the southern highland zone of Tanzania whose climate is greatly influenced by its diverse physiographic features and highly variable topography. The basin is characterized by tropical wet climate with mean annual rainfall ranging from about 650 mm in the south to as high as 2,500 mm in the Ufipa highlands. The basin climate is highly variable, with the basin peripheries exhibiting cooler temperatures and the basin floor, much of which is covered by Lake Rukwa, being much warmer and receiving less rainfall. The basin experiences only one rainy season with most rainfall occurring during November to April, and June to September receiving virtually no rain. Temperatures vary according to altitude but generally range from about 12˚C in the highlands to about 30 ˚C in the lowland areas, with the southern part of the basin being warmest.
The basin hydrology is characterized by an extensive network of seasonal and perennial rivers that feed and drain several small lakes and large expanses of swamps and wetland systems before all discharging into Lake Rukwa. The complex hydrological system enables the basin to support its vast and unique terrestrial and aquatic ecosystems, and a great diversity of plant and animal species, many of them endemic to the basin. Lake Rukwa is the main hydrological feature of the basin. The lake, which is an inland drainage lake with no outlet, is quite shallow with a mean depth of about 4 m and a highly changing shoreline. The Lake is fed by a total of 17 rivers, ranging in size from big perennial rivers to small seasonal rivers. The major rivers draining the basin include the Rungwa River which drains into Lake Rukwa from the north; Rivers Lupa, Chambua, and Songwe, which drain the Mbeya Range and flow into the lake from the south; and the Momba River, which flows into the lake from the west. Other rivers include Luiche and Katuma that originate from the Ufipa plateau and several ephemeral rivers that flow into the lake during the wet season.
Lake Rukwa Basin comprises of five socio-economic zones
Map socioeconomic zones
The highland zone covers the south-eastern part of the basin including the central Mbeya plain and Poroto highlands. It is characterized by generally good fertile soils, reliable and plentiful rainfall, moderate temperatures, and high agricultural potential. Read more
|Ufipa Plateau Zone
The Ufipa Plateau zone lies between the two wings of the rift valley formed by lakes Rukwa and Tanganyika. The plateau is mostly grassland and considered to be one of the most productive areas in the basin with good fertile ferralitic soils and reliable rainfall. Read more
The Rukwa Valley lies between the Lyambalyamfipa escarpment on the western side and the Lupa escarpment on the eastern side and stretches north-westwards from Lake Rukwa. The area is characterized by extensive flat plains Read more
The Gold Mining zone extends over most of Chunya DC and covers the north and central Chunya plain and Msangani plateau. The predominant features are the popular Gold mining areas and miombo woodlands. Read more
The Miombo Socioeconomic zone occupies most of the north central part of the basin. The area is largely uninhabited, dominated by vast miombo woodlands, and is widely infested with tsetse flies. Read more