North-South Carrier

North-South Carrier
Botswana showing the NSC route, and proposed extension from the Zambezi
Location
Country	Botswana
State	Central District
Coordinates	21°51′07″S 27°43′55″E / 21.85183°S 27.731989°E / -21.85183; 27.731989
General direction	North-South
From	Letsibogo Dam
Passes through	Selebi-Phikwe, Palapye, Mahalapye
To	Gaborone
General information
Type	Water
Operator	Water Utilities Corporation
Commissioned	2000
Technical information
Length	360 km (220 mi)
Diameter	1,400 mm (55 in)
No. of pumping stations	4
Pumping stations	Letsibogo, Moralane, Palapye, Serorame Valley

The North-South Carrier (NSC) is a pipeline in Botswana that carries raw water south for a distance of 360 kilometres (220 mi) to the capital city of Gaborone. Phase 1 was completed in 2000. Phase 2 of the NSC, under construction, will duplicate the pipeline to carry water from the Dikgatlhong Dam, which was completed in 2012. A proposed extension to deliver water from the Zambezi would add another 500 to 520 kilometres (310 to 320 mi) to the total pipeline length. The NSC is the largest engineering project ever undertaken in Botswana.

Botswana has an arid climate, with little in the way of surface water supplies. Until recently, groundwater wells were used to meet about 80% of demand for water. Some of the groundwater accumulated long ago when the climate was wetter. "Groundwater mining" is not sustainable in areas where the water is not being renewed from the surface. The more populous eastern portion of Botswana lies in the Limpopo River basin, which is considered "closed". In the South African portion of the basin, water usage exceeds the potential water yield from the basin by 800,000,000 cubic metres (2.8×10¹⁰ cu ft) annually. Water has to be imported from the Vaal River to make up the shortfall.

Almost all rainfall occurs in the summer months of October through April, at a time when temperatures over 30 °C (86 °F) cause high levels of evaporation. Rainfall is undependable. A drought period may last for several years. Precipitation is highest in the northeast, at about 690 millimetres (27 in) annually, and lowest in the southwest, at about 250 millimetres (9.8 in) annually. Annual average potential evaporation is about 2,000 millimetres (79 in) annually. Botswana has flat terrain that is mostly unsuitable for reservoirs.

In 2008 Botswana had a population of 1,921,000. GDP per capita on a purchasing power parity (PPP) basis was $13,415. 83% of the people were literate. The percentage of people with access to safe drinking water rose from 77% to 96% between 1996 and 2006. The economy of Botswana is growing fast, as is the population, particularly in the Gaborone area. This is causing growth in per-capita demand for water, and rapid growth in total demand. The Gaborone region accounts for over 75% of water demand in eastern Botswana. The local Gaborone and Bokaa dams cannot meet the growing demand even with the help of reclamation from the Gaborone Water Treatment Works at Glen Valley.