Riverine management key to flood control

Durban is the first city in Africa to release its Climate Action Plan, which includes strategies to conserve and manage its ecological resources, especially river systems. This is because human health and safety risks are being increasingly linked to poor riverine management.

By Kirsten Kelly

Part of eThekwini Metropolitan Municipality (EMM), Durban has 18 major river systems. The deteriorating river water quality and more frequent flooding have caused escalating costs to the city, businesses and its residents.

“The projected impacts of climate change on Durban’s water systems include declining water quality, more intense flooding, as well as reduced water availability and food security. When combined with blocked rivers and streams, and settlements in flood-prone areas, the impact of a changing climate is disastrous,” says Dr Sean O'Donoghue, senior manager: Climate Change Department, EMM.

During last year’s floods, water in some of Durban’s river courses damaged or ripped away close to R25 billion in infrastructure. Over 450 lives were lost and, ironically, the floods caused water supply interruptions; the city has not yet fully recovered from these floods. There was also an increase in the cost of purification of water to potable standards due to poor quality of receiving waters.

“Roughly 80% of the destructive river blockage in April was due to alien invasive plants rather than solid waste or litter. Since these alien invasive plants have shallow root systems (in contrast to the deep-rooted indigenous vegetation), they can be stripped out easily, leaving the soil exposed. During large storm flows, the aliens wash away easily, causing further erosion of larger trees and sandy soils, which blocks culverts further downstream,” explains O’Donoghue.

Historically, culverts were designed using hydraulic capacity calculations, with not enough thought given to the debris carried by rivers during storm events. Now, due to the more recent proliferation of alien vegetation and increased volumes of trash dumped in local rivers, the frequency of blockages has increased.

Transformative Riverine Management Programme

However, there was comparatively minor damage from the 2022 floods in areas where riverine management took place. The INK (Inanda, Ntuzuma and KwaMashu) areas and part of uMlazi where the Sihlanzimvelo Project has been implemented fared well compared to other parts of the city. The programme is part of EMM’s Transformative Riverine Management Programme (TRMP). According to O’Donoghue, the TRMP has received additional political, administrative

TRANSFORMATIVE RIVERINE MANAGEMENT PROGRAMME (TRMP)

The Durban TRMP is premised upon existing riverine management initiatives, with the aim to upscale them: 1

The Sihlanzimvelo Project (we are cleaning the environment) was started by EMM’s Roads and Stormwater Maintenance Department in 2012. The objective of the project is to remove litter, waste and invasive plant species from stream areas to reduce stormwater blockages and create employment for cooperatives formed by local residents. The community cooperatives employed through the Sihlanzimvelo Project have been given the core skills needed to establish and run a cooperative, remove alien invasive plants, and comply with health and safety regulations. The community assessors play a wider role in creating awareness and behaviour change in the surrounding communities. The current Sihlanzimvelo project covers nearly 500 km of rivers on municipal land where human settlement densities are high, creating more than 600 jobs for local community cooperatives. 2

The Aller River Pilot Project is led by the Kloof Conservancy, a community-based organisation promoting environmental protection awareness. The objective of the pilot project is to restore sections of the Aller River, with a focus on water quality improvement and invasive species removal. It has a focus on training and empowering youth representatives through the Eco-Champs programme to undertake education and clean-up campaigns. The project was initiated in 2016 and is ongoing. 3 and private sector support due to the 2022 floods.

The Green Corridors Green Spaces Project is led by the Green Corridors NPC, an EMM-supported special-purpose vehicle, working on community upliftment through the creation of a green spatial economy. The objective of the project is to enhance local quality of life, living environments and sustainable livelihoods. This project was initiated in 2010 and its implementation is subjected to an annual review of its memorandum of agreement with the municipality.

The TRMP has been implemented to enhance the city’s resilience to the impacts of climate change. This is done by combining ecosystem restoration, adaptation to climate change, and the creation of economic opportunities for low-income populations. It encompasses the employment of community cooperatives as well as the training and employment of local community members to assist with river health maintenance, waste management, monitoring and community awareness.

The main tasks of the cooperatives include:

• clearing of culverts and stormwater systems in April was due to alien plants rather than solid waste or litter. Since these alien invasive plants have shallow root systems (in contrast to the deep-rooted indigenous vegetation), they can be stripped out easily, leaving the soil exposed. During large storm flows, the aliens wash away easily, causing further erosion of larger trees and sandy soils, which blocks culverts further downstream.”

• minor erosion control of embankments

• ditching to prevent water stagnation

• litter and debris removal and disposal

• cutting back of vegetation

• alien vegetation control

• planting of indigenous vegetation

• report leaking sewers and erosion points.

The state of the cooperative’s length of stream is assessed each month against a set standard, with the payment scale determined by the level of maintenance achieved.

“Our thinking is that by looking after waterways by removing alien vegetation and plastic litter that can be repurposed into something else, the riverbeds will be more resilient to flooding. This will offset anticipated damage and loss of lives from climate change. While the removal of alien plants can reduce flooding risks, it can also increase water security by improving infiltration and base flows in rivers,” adds O’Donoghue.

There is a focus on building skills and capacity in beneficiary communities, extending beyond riverine management actions. This includes helping people making a living from waste upcycling and recycling while improving the health of their local rivers. “For example, dirty plastics coming out of the river can be used to manufacture clip boards and ocean pavers. Alien vegetation can be converted into new fibre-based products or bokashi compost,” states O’Donoghue.

“Another initiative that we are looking to implement is to stabilise the riverbeds with indigenous vegetation once the alien plants have been removed. There is an opportunity for community members to grow indigenous plants from seeds and sell them back to EMM to plant back into riverbeds,” he adds.

There are 7 400 km of Durban’s degraded rivers and streams. EMM owns roughly 1 200 km, while the rest is traditionally owned and privately owned land. “A different model will need to be adopted on land that is not owned by EMM. The idea would be to work with NPOs and private companies whose operations are at risk due to flooding.”

Partnerships

Projects falling within the TRMP represent partnerships between EMM, Agence Française de Développement (AFD), Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), civil society groups, and communities. AFD is a member of the C40 Cities Finance Facility, and a co-funder of Ciclia (Cities and Climate in sub-Saharan Africa) – a financial facility to provide project preparation funds. The C40 Cities Finance Facility has provided support to the TRMP, with GIZ as an implementing agency.

“AFD has worked with EMM for over a decade, and can provide grant funding at a subsidised interest rate. We focus on funding to prepare projects for practical completion,” explains Yasmeen Dinath, chargeè de mission: Urban Development and Municipalities, AFD.

Critical to the successful implementation of the TRMP has been the development of a viable business case that quantifies and articulates the costs and benefits of transformative riverine management across different sectors. The development of this business case is supported by the C40 Cities Finance Facility.

Business case

The business case seeks to unlock increased investment from the municipal fiscus in ecological infrastructure as a supplier of vital goods and services, but also from other government actors, non-governmental and private sector stakeholders, as well as citizens. And it is a means to building a case for upscaling riverine management to encompass all rivers in Durban.

“Several studies (upon which the business case has been based) were run around the hydrology of the four catchments with the TRMP, analysing present and future scenarios. Ecosystem services, vulnerabilities, open space management and the effects of climate change was considered. There was a huge emphasis on community-based stakeholder involvement in the catchments,” adds Dinath.

The business case suggests that the historic failure to invest in (often ill-defined or intangible) ecosystem services has led to a significant decline in the condition and functionality of most of the city’s rivers. Declining river water quality will affect coastal tourism and property values, as well as the ability of riverine communities to access and use rivers for household water provision, crop irrigation and recreation.

O’Donoghue estimates that the TRMP saves the city at least R59 million every year, based on avoided costs of damage to road culverts alone. “For evert R1 spent on ecological infrastructure, anything between R1.80 and R3.40