Our Burning Planet OP-ED
How Nelson Mandela Bay and Kouga’s looming Day Zero water disaster could have been prevented
The Nelson Mandela Bay Metro and adjacent Kouga Municipality will soon run out of water. Most of their water comes from three dams which are nearly empty and have been for more than a year. Their catchments are degraded by alien tree invasions, overgrazing and wetland destruction. Radical action is needed to restore their functioning — the cost of doing otherwise is beyond contemplation.
Professor Richard Cowling is emeritus professor of ecology at Nelson Mandela University. He is locally and globally recognised for his research on the evolution and conservation of diversity in Cape biomes, the ecological resources that sustained human evolution on the Cape coast, and the restoration of degraded ecosystems. He divides his time between surfing, botanising and thinking about how to dampen the effects of the looming socio-ecological dystopia.
Like most dams in South Africa, the three in the Kromme-Kouga-Baviaanskloof catchments depend on stormflows after floods to fill them up. It’s been 10 years since a dam-filling rainfall event occurred in this region. Disaster has been averted largely through the contribution of small rainfall events and baseflows (the portion of the streamflow that is sustained between rainfall events).
These dry-period flows, the lifeblood of drought-stricken catchments, are pivotal for maintaining water security. When catchments are degraded by water-thirsty alien trees, overgrazing and the destruction of wetlands, baseflows are depleted and rivers stop running. Dams dry up and human suffering escalates.
Given the importance of the Kromme-Kouga-Baviaanskloof catchments for water delivery, it is not surprising that they were prioritised by Working for Water, a public works programme of the Department of Forestry, Fisheries and the Environment aimed at creating employment and improving water yields by clearing invasive alien plants. Scientists have known for decades that invasive alien trees such as wattles, pines and gums can deplete watersheds of baseflows, especially during times of low rainfall.
Started in 1995, this project has up to now cleared 27,000ha in the Kromme and 28,000ha in the Kouga catchments, but much more work needs to be done, especially in the Kouga catchment. A 2012 study showed that at the current rate of clearing, the time required to fully restore the Kromme and Kouga catchments was 54 and 695 years, respectively. The effectiveness of these projects is greatly compromised by the reluctance of landowners to keep their properties free of aliens once Working for Water has cleared them.
In the early 2000s, Working for Wetlands — another Department of Forestry, Fisheries and the Environment public works programme — implemented work to stabilise head cuts that were eroding the remnant wetlands of the Kromme floodplain. In pre-colonial times, the entire length of this floodplain was covered in palmiet (Prionium serratum) wetlands; today, they cover barely 15%. Palmiet is a tough-leaved, sedge-like plant with an extraordinary capacity to trap moisture, silt and organic matter, accumulating as massive (up to 6m deep) peatlands. Runoff is held in this natural sump or supersponge, seeping slowly downstream and persisting even during prolonged droughts as baseflow that ensures low, but significant flows into impoundments.
Palmiet is — surprisingly for a wetland plant — extremely thrifty with water. Despite growing in water-saturated soils, it uses on average less water than dryland fynbos shrubs, markedly less than the invasive black wattle, and about half the amount evaporated from open stored water. Therefore, trapping run-off in palmiet wetlands makes perfect sense for water conservation. However, throughout most of the Kromme valley, the wetlands have been cleared and drained for cropping and are consequently incised and eroded. This produces rapid, erosive flows after rain, rather like water coursing down a canal and into the dams, where much is evaporated.
Research has shown that for a given amount of rainfall in the catchment, the speed of streamflows into the Kromme Dam have increased steadily over the past 70 years, concomitant with the pace of destruction of the wetlands. Building drought resilience into the Kromme system will require the comprehensive restoration of palmiet wetlands.
The Kouga River catchment, which lies west of the Kromme, comprises a huge area of protected mountain wilderness of the Baviaanskloof World Heritage Site to the north, pine-infested Tsitsikamma Mountains to the south, and in the centre the Langkloof valley, the site of capital-intensive, deciduous fruit farms that produce a lucrative export crop. Like the Kromme valley, the rivers of the Langkloof are in a mess: floodplains are cultivated, which means that croplands need to be protected by the engineering of river courses to facilitate rapid flows downstream; basically, turning them into canals. Illegal dams abound.
And, of course, despite Working for Water’s best efforts, bottomlands are choked with black wattle while pines run rampant on the slopes; landowners, who are legally responsible for clearing invasives, do next to nothing. Furthermore, neglected and broken water treatment works have been spilling raw sewage into the tributaries of the Kouga River for decades.
In the wilderness country, the entire length of the Kouga River and all its tributaries are densely invaded with black wattle. These infestations deplete water flows already compromised by pine invasions on the northern slopes of the Tsitsikamma (the most water-productive part of the river’s catchment) and extractions from mostly illegal dams to feed the growing deciduous fruit industry. Owing to the difficult terrain, Working for Water has made less progress in clearing this catchment than in the Kromme. The designated manager for the World Heritage Site — the Eastern Cape Parks and Tourism Board — has failed to implement effective alien clearing along these rivers.
A major tributary of the Kouga — the Baviaans River — drains the iconic Baviaanskloof, a spectacular intermontane valley. The valley walls, which once supported dense spekboom thicket, have been denuded by livestock overbrowsing; where once there was a dense, green canopy that absorbed rainfall and slowly released clean water into the Baviaans River, there is now exposed, eroded earth that allows precious rain to run unabated in silt-laden flows.
Research has shown a more than hundredfold lower infiltration in soils with degraded thicket relative to the soils beneath the intact spekboom canopy. This results in lower levels and less retention of soil moisture, almost double the amount of runoff, and an almost sixfold increase in sediment load in degraded thicket relative to intact spekboom thicket. Restoring degraded thicket by planting spekboom truncheons — a well-researched, proven processwill reduce erosion and improve baseflows, while also restoring biodiversity and sequestering unusually large amounts of carbon dioxide for the semi-arid vegetation.
Working for Ecosystems, a sub-programme of Working for Water, has over the past 15 years invested in research and implementation for large-scale spekboom restoration. The collapse of the carbon price after the Great Recession of 2008 undermined the viability of private-sector funding of spekboom restoration. The renewed and urgent focus on anthropogenic climate change, in conjunction with the declaration by the United Nations of the 2020s as the Decade of Restoration, should re-energise thicket restoration using spekboom. Hopefully soon, the bare, eroded slopes of the Baviaanskloof valley will once again support a dense mass of rain-retarding spekboom thicket.
A 2010 modelling study showed that restoring the 225,000ha of ecosystem degraded by alien plants and overgrazing in the Kromme-Kouga-Baviaanskloof catchments would increase water yield and baseflow by 11 and 14 million cubic metres per annum, respectively, and reduce sediment loads by 22 million cubic meters per annum. The increase in yield alone amounts to 16% of water drawn each year from the dams on these catchments by Nelson Mandela Bay.
The contribution of baseflows is crucial in times of drought, such as at present; the model estimates for these flows are an underestimate, since the model fails to consider the impact on baseflows of restoring palmiet wetlands in the Kromme.
The model also predicted that catchment restoration would yield positive economic values for a bundle of ecosystem services, namely water delivery, sediment load reduction, carbon sequestration and biodiversity-based tourism. Indeed, the economic analysis yields a highly favourable benefit-cost ratio of 3.27.
But who is going to pay the costs of restoring these catchments — an estimated R1.3-billion over 30 years? Negotiations with Nelson Mandela Bay on a restoration levy have gone nowhere, which is not surprising given the dysfunctional governance of this city.
Commercial agriculture, especially the lucrative citrus and deciduous fruit sectors, could also be expected to contribute to restoration. It may well be possible to use carbon credits to finance the restoration of spekboom thicket, and this could happen rapidly given that there is private-sector experience in project development and implementation.
Tourism benefits largely accrue to small vendors who operate on tight margins in a fickle industry. Livestock farmers similarly are financially constrained and are unlikely to be able to afford a restoration levy.
The question we need to ask, however, is: what will be the costs of not restoring these catchments? What will be the impact on the economies and wellbeing of people living in the downstream cities and towns which need sustained investment to create the quality jobs so badly needed by their growing populations of economically marginalised people? What will become of Nelson Mandela Bay’s industrial heart? And what future is there for the irrigation agriculture in the Langkloof and Gamtoos valleys, or the tourism enterprises of the Kouga coast? Without a secure source of water, the region is doomed to economic decline.
Who will implement the restoration? Up until now, only the Department of Forestry, Fisheries and the Environment’s expanded public works programmes have been active in the region. The resources allocated to these are woefully inadequate for the effective and efficient restoration of these catchments.
Moreover, the department’s programmes in the region have begun to falter: not once in the past six years has Working for Water come close to achieving its annual targets in the region. This is not the fault of the private-sector implementing agent, but a result of growing dysfunction of state governance in the past decade. The transaction costs of doing business with Working for Water are punitive, a consequence of the sheer incompetence and mendacity of some officials, as well as additional controls on transactions to counter the corruption epidemic gripping this country.
Part of the answer to implementation lies in embracing the private sector. For example, the demand globally for high-quality biocarbon products such as biochar is a significant opportunity for clearing invasive trees; mobile kilns could cost-effectively produce large quantities of these products for the export market. There are not many places in the world where felling trees is an environmentally appropriate action that delivers ecosystem services, creates quality jobs and attracts foreign investment.
However, the state has a crucial role in implementing restoration via the fostering of cooperative governance between the private sector, civil society and relevant government sectors, such as environment affairs, water affairs, conservation, agriculture, disaster management and tourism. It is the state’s role to enforce in these catchments our nation’s excellent water and catchment management legislation. This may require withdrawing agriculture where it has encroached on wetlands and floodplains.
These actions, with the imposition of restoration levies, will not be popular. But we must keep reminding ourselves about the cost of not restoring these catchments. Given a future where climate change will result in more frequent and intense droughts, ineffective action is beyond contemplation. DM
Disclaimer: Richard Cowling is a co-author of the scientific studies cited in this article.