1.1.1.WATER RESOURCES Lesotho is located entirely within the Orange River Basin. The major sub-basin river systems in Lesotho are: -The Senqu (Orange), which drains two-thirds of Lesotho (24,485km2), originates in the extreme north of the country and leaves Lesotho near Quthing. In its catchment area, four large dams will be constructed under the Lesotho Highlands Water Project (LHWP). -The Makhaleng, with a catchment area of 2,911km2, originates in the vicinity of Mount Machache and leaves the country near Mohales Hoek. -The Mohokare (or Caladon) marks the border with South Africa and has a catchment area of 6,890km2. It springs from Mount Aux Sources, and leaves Lesotho near Wepener. All its major tributaries are located in Lesotho. The Lets’eng-la-Letsie wetland in the Quthing district was tentatively designated as a RAMSAR site by the government as part of its accession to the RAMSAR Convention. Lesotho’s natural renewable water resources are estimated at 5.23km3/yr, by far exceeding its water demand. Due to Lesotho’s commitments in the framework of the LHWP, its actual water resources will have decreased to 3.03km3/yr by 2020. Groundwater resources are estimated at 0.5km3/yr. Aquifer yields are low: of a sample of 818 wells, only 12 per cent yielded above 1l/s; average well depth was 65m in intrusive, sedimentary or volcanic rock, and 28m in alluvial rock. In 1995, about 3300 wells, equipped with hand-pumps, served the rural population in the lowlands, while 10 per cent of the urban municipal production originated from groundwater. Except for the area around Maputsoe (aquifer yield 50l/s), the potential for irrigation with groundwater in Lesotho is low. Major dams have been constructed in the framework of Phase I of LHWP: -Katse Dam in the Central Maluti Mountains was completed in May 1997. It is a concrete arch dam, 185m high, with 710m crest length and a storage capacity of 1.95km3. It impounds the Malibamatso River catchment (1,866km2); -Mohale Dam is a concrete faced rockfill dam, 145m high, with 540m crest length. It impounds the Senqunyane River catchment (938km2) and has a storage capacity of 0.86km3; -Muela Dam, a 55m high, 6 million m3 capacity dam acts as the tailpond of the Muela hydropower station. Phases II, III and IV of the project foresee the construction of Mashai Dam (3.3km3), Tsoelike Dam (2.22km3) and Ntoahae Dam.

1.1.2.WATER USE In 2000, the total water withdrawal was estimated at 43.6 million m3. Industry is the main water user with 22 million m3 (51 per cent) followed by municipalities with 21 million m3 (48 per cent) and agriculture with only 0.6 million m3 (1 per cent).

1.2.WATER QUALITY, ECOSYSTEMS AND HUMAN HEALTH Lesotho’s ecology is fragile because of the mountainous topography, the thin soil layer and the limited vegetative cover. Population pressure has forced settlement in marginal areas, resulting in overgrazing, severe soil erosion, soil exhaustion and desertification. Poor management practices and infrastructure improvements have had serious negative impacts on water resources, through the destruction of wetlands and their hydrological functions, changes in water regimes due to overgrazing and inappropriate cropping practices, and increased sediment production caused by mining and road construction. Water pollution by slurry from diamond mines is recognized as an environmental problem.

(Water Risk Filter)