Where we work

An Introduction

Where We Work pages are under development.  They will describe important sites, key species, environmental pressures, and management solutions that will help safeguard nature in the river basin.

Physical Description

The river basin lies entirely within Zambia and covers an area of about 157,000 km2.  It is mostly gently undulating terrain between 1,000 – 1,300 m elevation, but the land rises to 1,520 m in the extreme north-west and falls precipitously on approach to the confluence of the Kafue and Zambezi rivers at 370 m.

The area has a tropical continental climate, with a  cool dry season from May to August, then an increasingly hot dry season until late October or November, followed by a warm rainy season through to March or April.  Mean annual rainfall varies from around 1,300 mm in the North to around 750 mm in the extreme South.  Average temperatures vary from about 15° C in July to about 22° C in November but temperatures and potential evapotranspiration tend to be higher in the South, in line with elevation (and humidity and cloud cover).

Potential evapotranspiration varies greatly across the area, being determined by temperature, relative humidly, wind speed and sunshine. Annual evapotranspiration (based on FAO CROPWAT data) values vary from 1,000 mm to almost 2,000 mm, with an average of some 1,600 mm – almost double the average annual rainfall in the South of the basin. Irrigation is thus essential in most areas to guarantee crop yields for seasonal crops.

The Kafue River is c. 1,600 km – 1,000 miles – long, with a mean flow at Kafue Gorge of 320 m3/s, representing about 9% of the total flow of the Zambezi River.

Land Cover/Use

The terms ‘land cover’ and ‘land use’ are often used synonymously. ‘Land cover’ refers to the actual coverage of the surface of the earth with various natural or man-made features, whereas ‘land use’ refers specifically to the use of the land cover. Land cover/use has a great impact on water resources – it affects how precipitation that falls on the ground eventually translates into runoff, infiltration, evaporation, and the quality of the water.

Land Cover in the River Basin. Courtesy of the ESA.

Land Cover in the River Basin. Courtesy of the ESA. (Click to enlarge)

Woodlands and bushlands cover about half the basin and and forests a third, mainly in the wetter North.  Wetlands are poorly defined but occupy at least 6% of the area.

Almost half the river basin is designated as National Park, Game Management Area, Forest Reserve, Wetland of International Importance, or Important Bird Area.   It includes Kafue, Lochinvar and Blue Lagoon National Parks, and the Kafue Flats, Busanga and Lukanga Wetlands of International Importance.

Environmental Pressures

The population of about 3.85 million people is concentrated in towns and cities along the northern, eastern and southern watersheds.  By contrast the population density in central and western parts of the basin is very low (e.g. 3/km2 in  Kasempa District).

The mainstay of the economy is mining and manufacturing in the northern towns; manufacturing and farming in the East, and farming in the South.  The rural areas are poor, people subsisting largely on unreliable dryland crop production.

Quarrying stone from a Kabwe mine dump. Courtesy Carl O'Keefe.

Quarrying stone from a Kabwe mine dump. Courtesy Carl O’Keefe.

Mining for copper, lead and cobalt has left a legacy of polluted land and water courses and intermittent problems still arise. In 2007, Kabwe was listed by the Blacksmith Institute amongst the World’s worst ecological disaster areas due to the toxic effects of lead and cadmium pollution from the local smelter on local residents.  Elevated levels of heavy metals have also been detected in wildlife far downstream in the Kafue River though their impact on wildlife populations is unknown.

Development of the Kafue Gorge hydropower project in the 1970s to supply electricity to the mines has had severe consequences for people dependent upon the wetland and aquatic resources of the Kafue Flats, once described as the most productive floodplain in southern Africa due to its rich fisheries, abundant wildlife and dry season grazing for cattle.  Flood levels on the Flats are now regulated by an upstream storage reservoir at Itezhi-tezhi that inundated some 390 km2 of land in Kafue National Park, and by the downstream dam at the head of Kafue Gorge, that inundates the eastern end of the Flats.  The fisheries, wildlife populations, and availability of dry season grazing have all declined and in recent years an alien, invasive shrub Mimosa pigra, has spread rapidly over a large part of the remaining floodplain.

Rural and urban poverty has created a strong demand for bushmeat and charcoal for fuel.  Poaching is a widespread problem, and many of the 109 Forest Reserves registered in 2002, especially near the urban centres, have now been encroached, cut over and degazetted.