Global IssuesSOUTHERN AFRICA: Neglected Land Washing Away
Damage to wetlands high in Lesotho's Maluti mountains has impacts on the health of the whole of the Orange-Senqu river system.
The wetlands in this mountainous region stabilise soil, retain sediment and contribute to river flow from this area of high rainfall.
In so doing, they indirectly support the Lesotho Highlands Water Project (LHWP), which captures water in dams and supplies it to water-thirsty South African industry and agriculture. The water Lesotho sells to South Africa is the mountain kingdom's largest source of foreign income.
However, a combination of factors, including infrastructure development, overgrazing and cultivation and the resulting erosion, has led to the wetlands being degraded.
A study produced in 2008 for the Orange Senqu River Commission (ORASECOM), titled 'The Protection of Orange-Senqu River Water Sources', said some of the wetlands surveyed were dissected by deep gullies, indicating elevated erosion rates. The study focused on the catchment area of the Khubelu River, which is a major tributary to the Orange-Senqu.
'The degradation of the wetlands vegetative cover may reduce the ability of the wetlands soil to dissipate the erosive water forces. As such, rills and channels have formed resulting to gullies with extended soil scouring.' The study found the wetlands had varying levels of degradation and gave the reasons as infrastructure development, uncontrolled livestock grazing and trampling and encroachment by cultivation.
With wetlands crucial for retaining water, purifying it and also regulating the flow of water, degradation of the wetlands affects the water supply in the LHWP.
In addition, the erosion had contributed to increased sedimentation of water downstream of the wetlands and thus in the Orange-Senqu river system, said the study.
The Caledon River flows from Lesotho into South Africa. Silt build-up in the river has had major implications for communities on the banks of the river.
The sedimentation problem in the river, which joins the Orange River and flows into the Gariep Dam in South Africa's Free State province, is the worst in South Africa and possibly the worst in the world, said Peter Pyke, a task team member of the Orange-Senqu River Commission (ORASECOM).
ORASECOM, set up under the SADC Shared Watercourses Protocol, was founded in 2000 with a focus on the use of shared water resources to address issues of poverty and food security.
Pyke, who was briefing ORASECOM delegates touring the Southern African region, said the sedimentation problem is caused by natural factors such as easily-eroded sandstone and rainfall, but aggravated by human factors such as a growing population.
Pyke, who is also a chief engineer for options analysis with South Africa’s water affairs department, said the silt build-up had in some areas added at least six metres to the river bed. In one area, a weir which used to have a three metre waterfall had now been completely buried by sand.
Further downstream, a new bridge has been built because the older one had flooded even in periods of minor flooding.
Because the bed of the river is now so much higher, farmland on either side of the river is now also subject to flooding.
Pyke said the problem was worse upstream of the Welbedacht Dam, built in the 1970s, because as the velocity of the water slowed before reaching the dam, sediment was deposited behind it.
Silt build up in the dam means it now stores less water. Initially built to hold 115 million cubic metres, the dam's reservoir now contains between seven and 15 million cubic metres.
Lesotho's Sechoocha Makhoalibe, who has worked as a regional project manager for previous ORASECOM studies, said the situation has been aggravated by land use management issues.
He said land tenure in the area was communal and this could lead to problems in taking care of land. Land disputes between local chiefs and community councils had a negative impact because it could mean that land was not taken care of, he said.
The 2008 report produced for ORASECOM recommends that a programme for conservation, rehabilitation and protection of the wetlands in the highlands of Lesotho would need to involve activities carried out by the local communities and the local government structures.
It would have to address range management, rehabilitation of degraded wetlands, a lack of information and monitoring capacity.
The study proposed four main interventions, which have been incorporated into rehabilitation work being done by the government of Lesotho, to be implemented by community, water, road and soil stakeholders.
These include range management to improve livelihoods of the 20,000 strong population in the area, rehabilitation of degraded wetlands, prevention of erosion from road drainage and the monitoring of results so that lessons learnt could be replicated in other areas.
*This is the fourth in a series of articles on the Orange-Senqu River Basin.
© Inter Press Service (2009) — All Rights ReservedOriginal source: Inter Press Service