Ecosystem-based Flood Management: A comparative study report of the cities of Cape Town and Durban (South Africa), Nairobi and Mombasa (Kenya) – South Africa

Urban floods are becoming more common as a result of increased urbanization, poor urban planning, and climate change. A new report from PlanAdapt explores how the cities of Cape Town, Durban, Mombasa and Nairobi are rising to the challenge and how their work can inspire others.

Understanding Flood Management

Floods pose a major threat to cities in the Global South, due to a combination of factors including unplanned city sprawl, prevailing poverty, and low adaptive capacity.

Depending on the location, physical characteristics and risks of climate change in different urban areas, they can be affected by different types of floods.

Rapid urbanization is challenging cities’ ability to learn from past mistakes and build resilience. However, there is a wide range of interventions and measures to reduce flood risks at different levels.

PlanAdapt, with support from CDKN, has undertaken a comparative study of four African cities and their approaches to flood risk: Cape Town, Durban, Mombasa and Nairobi. The study is now used for valuable exchange and peer learning between district and municipal officials in those cities in South Africa and Kenya.

It is also used in Accra, Ghana, where CDKN is working with municipal officials who are eager to benefit from peer learning – and the report could benefit many other cities.

* Ecosystem-based Flood Management: Report of a comparative study of Cape Town, Durban (South Africa), Nairobi and Mombasa (Kenya) * Highlights the use of an Integrated Flood Risk Management (IFRM) approach such as Ecosystem-Based Adaptation. IFRM includes a combination of infrastructure as well as non-structural elements (changes in institutions, processes and plans) to reduce flood risk and improve flood resilience.

Climate change has led to more erratic rainfall in the respective cities. Ecosystem-based approaches aim to restore and enhance the natural dynamics of ecosystems in order to fend off the negative effects of climate change. These methods can provide many environmental, social, economic and biodiversity benefits, as well as flood risk management solutions.

Specifically, ecosystem-based approaches such as restoring rivers, mangroves, and sand dunes, and protecting kelp beds and wetlands, have demonstrated broader benefits for communities by improving public health, protecting livelihoods, and creating new income-generating opportunities.

Ecosystem-based approaches are sometimes referred to as ‘green infrastructure’, in contrast to traditional ‘gray infrastructure’ solutions such as formwork for sea walls, river channels, etc.

Learning from South African and Kenyan cities

While Durban, Cape Town, Mombasa and Nairobi each have their own political, social and cultural context, they find themselves facing similar challenges when it comes to floods. In both South Africa and Kenya, rapid urbanization is increasing impermeable roofs and areas that lack solid waste management or inadequate drainage systems. Informal settlements located in flood-prone areas are particularly affected. These challenges are exacerbated by the effects of climate change such as heavy rainfall and drought.

With these similarities in mind, it is useful to understand how each selected city responds to its own circumstances with a mixture of green and gray infrastructure and non-infrastructure solutions. Cooperative modes of governance that take a whole-of-society perspective appear to be the most effective.

integrated approach

Flood and water management requires the participation of a wide range of stakeholders and institutions as well as collaboration within and across organizations, sometimes over a long period of time. It is essential that practitioners and administrators inform the knowledge-gathering process, creating an evidence base of what works and what does not. The role of CSOs and NGOs in the affected communities is imperative as well, to understand flood management from a local perspective.

Cooperation and participation are required of municipalities, provinces, states and sometimes national governments, because the scale of the river basin or the catchment area, and thus the effects and measures often extend beyond the municipalities. A nature-based approach to flood risk reduction requires a better understanding of hydrological system dynamics.

Examples of multi-actor collaboration in urban flood risk management include the diversionary river management program in eThekwini, South Africa (the municipality area that includes Durban). Here, the city government, with support from the C40 City Finance Facility, has collaborated with a variety of civil society organizations. For example, the Kloof Conservancy, a conservation NGO, focuses on protecting ecosystems and promoting environmental awareness. It implemented the Aller River pilot project, taking a pragmatic, partnership-based, community-led approach, focusing on engaging communities, while protecting nature.

The report found that while Durban and Cape Town have demonstrated maturity in their response to climate change across policies, planning and frameworks, it is clear that the Kenyan cities of Mombasa and Nairobi remain in the process of being protected from climate change. Especially for flood management.

The reason for Kenya’s emerging response to the effects of climate change at the city level is revealed in interviews with Kenyan city officials. PlanAdapt found that strong conventional thinking and urban planning practices prevailed, with a bias towards gray infrastructure approaches to flood management such as engineered drainage systems, canal widening and deepening, seawalls, dams and reservoirs, without consultation with surrounding communities. This traditional gray infrastructure response to climate adaptation fails to recognize and integrate the value of learning and collaboration between city authorities and non-state actors.

Meanwhile, multi-sectoral collaboration was found to be a key enabling aspect for mainstreaming the ecosystem-based adaptation approach into urban planning for both cities. For example, in Mombasa, the city government is working with the national government to address issues of land acquisition and the opening of natural waterways, which drain into the sea, to rehabilitate the environment. This collaborative approach aims to take advantage of available opportunities and open spaces, to integrate green infrastructure, and to rehabilitate local ecosystems to mitigate the effects of floods. Nairobi has a land use plan through which the city aims to preserve and restore green and blue infrastructure, to create an ecological network. This includes the preservation of existing forests and the restoration of rivers and river banks. Successful implementation of these actions will require collaboration with a range of actors including research institutes, the Nairobi City District Association and local practitioners in climate adaptation and disaster risk reduction.

Kenya can also learn lessons from South Africa, where the national government plays a strong role in guiding local authorities to explore and offer the potential for ecosystem-based adaptation solutions. This may help local governments to take responsibility for translating national policies on ecosystem-based adaptation into local mandates. However, challenges remain for the local government to fully respond to the floods due to land ownership issues as some areas are in private ownership and are out of their control.

A social justice approach is needed

Local governments also face the challenge of responding to the different effects of floods on different parts of the population: urban flooding is a localized event, but is unevenly suffered by urban dwellers. In most cases, research indicates that the most vulnerable and vulnerable slums, particularly in informal settlements, experience greater impacts.

Overall, this study found that Cape Town, Durban, Nairobi and Mombasa face similar drivers that increase flood risk, especially for vulnerable communities. These drivers include the rapid pace of urbanization, construction on unsuitable land, and greater climatic variability. The study also sheds light on the role of local contexts and social networks in translating national policies to the local level.

Informal settlement near Durban

Social networks include networks that exist at different levels and for different purposes. For example, the Cape Town Informal Settlements Network, the Biodiversity Network etc., and similarly, the Nairobi Risk Centre. Networks may have a role in shared learning, information exchange, and/or facilitation, often in collaboration with local governments, civil society organizations, universities or research institutions. Their role may overlap or overlap with governance processes, but it must be formally defined and defined.

It is clear that ecosystem and community-based approaches provide a means to address the multiple challenges encountered within informal settlements. Involving stakeholders, by identifying champions and communicating the co-benefits of ecosystem-based adaptation, in providing, for example, public health improvement has proven beneficial.

Furthermore, incorporation of social principles into the design and implementation of ecosystem-based adaptation for flood management is strongly recommended for reasons of social equity, given the vulnerability of certain social groups to climate-related urban flood impacts. A recently published technical report by FEBA, PlanAdapt and IUCN discusses seven social principles for creating clear links between ecosystem-based adaptation interventions and social or climate justice.

Accra, Ghana: eager to learn

So far, the results of the comparative study have been shared with stakeholders in the Ghanaian capital, Accra, where urban flooding is a persistent problem during the rainy season and threatens to become worse in a changing climate.

With CDKN support, five municipalities in Accra are working with the University of Ghana to address flood risks, with a particular focus on the use of nature-based approaches. Over the past two years, local officials have met at two events and have had ongoing engagements to learn from each other and coordinate their flood management approaches. Ghanaian officials intend to share the results of the study with stakeholders in the provinces as well as with their NGO partners.

Copies of the report and information summary will also be sent to high-level officials in ministries and agencies such as the Environmental Protection Agency (EPA) and the National Disaster Management Organization (NADMO).

The report has the potential to inform cities more broadly across Africa, which are facing the compounding pressures of rapid urbanization, including growing informal settlements, increasing unpredictable rainfall and flooding.

in-depth reading

Read the full report or a 4-page summary to learn more about ecosystem-wide and nature-based solutions for the scale of flood intervention.

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