Understanding the Challenge of Urban Floods
Floods have become an increasingly problematic issue in many cities, especially in the Global South, due to a combination of factors. High population density, unplanned land-use changes, increased impervious surfaces, poor solid waste management, and the settlement of people in flood-prone areas like floodplains and wetlands have all contributed to the rising threat of urban flooding. The advent of climate change has further exacerbated the problem, leading to more intense and frequent rainfall events that overwhelm existing infrastructure and coping mechanisms.
The situation is even more dire in informal settlements, where the lack of planning and access to basic services like drainage and waste management amplifies flood vulnerability. Historically, the apartheid regime in South Africa legally compelled Black Africans to live in marginalized settlements, leading to the proliferation of informal housing. Rural-urban migration has also fueled the growth of these settlements, which now number over 3,200 across the country. Floods in these areas typically destroy infrastructure, homes, and property, causing displacements, loss of life, and risks to health and livelihoods, further entrenching poverty.
Integrating Local Knowledge for Improved Flood Risk Mapping
Traditional top-down approaches to flood risk management often fail to capture the nuanced, context-specific factors that shape vulnerability in informal settlements. As part of our research, we found that the use of indigenous knowledge and participatory geographical information systems (GIS) in mapping flood risk is highly fragmented in South Africa. There is a limited integration of local community knowledge and inadequate participation in the mapping process, despite the valuable insights that these stakeholders can provide.
Local or indigenous knowledge is strongly linked to the cultural context and past experiences of a community, and can be a powerful source of resilience to flooding and other natural disasters. South Africa’s laws and regulations do make provision for using indigenous knowledge in disaster risk reduction, but the implementation of this approach remains relatively low, especially in urban areas.
Engaging with local communities and integrating their place-based knowledge can significantly enhance the accuracy and completeness of flood risk mapping. A participatory GIS approach can create a more detailed and nuanced “picture” of the places where floods could cause the most damage, as opposed to a purely top-down, technical assessment. By spatially visualizing the patterns and levels of flood vulnerability, the mapping process can help identify the people and areas most in need of support, enabling policymakers and other stakeholders to develop targeted strategies and interventions.
Implementing a Participatory Mapping Approach
To address the shortcomings of traditional flood risk management, we propose a collaborative, participatory mapping methodology that integrates technical assessments with community-driven knowledge and visions. This approach, which has been tested in the Sampierdarena district of Genoa, Italy, can serve as a model for other urban communities facing similar challenges.
The key steps in this participatory mapping process include:
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Stakeholder Engagement: Identify and engage a diverse set of stakeholders, including local residents, community organizations, government agencies, and technical experts. Ensure the participation of underrepresented groups, such as women, youth, and marginalized communities.
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Co-creation of the Participatory Map: Facilitate workshops and interactive mapping sessions where stakeholders can collectively identify and map flood-prone areas, critical infrastructure, and potential solutions like sustainable urban drainage systems (SUDS). This co-creation process allows for the integration of local, place-based knowledge with technical expertise.
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Spatial Analysis and Visualization: Utilize GIS tools to analyze the spatial data collected during the mapping sessions, visualizing patterns of flood risk, vulnerable areas, and potential SUDS locations. This analysis can help validate and enhance the community-generated knowledge, creating a comprehensive understanding of the flood risk landscape.
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Collaborative Decision-making: Engage stakeholders in a deliberative process to review the participatory map and the spatial analysis, jointly identifying priority areas and co-designing potential interventions and flood mitigation strategies. This collaborative approach ensures that the needs, concerns, and aspirations of the community are reflected in the final decisions.
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Iterative Refinement: Establish feedback loops and opportunities for ongoing refinement of the participatory map and the decision-support system. Regular updates, based on changing conditions and new information, will keep the process responsive and adaptable to the evolving needs of the community.
The Benefits of Participatory Mapping for Flood Resilience
The integration of local knowledge and community participation in the mapping of flood risk can offer several key benefits for urban resilience:
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Comprehensive Understanding of Vulnerability: By tapping into the place-based expertise and lived experiences of local residents, the participatory mapping process can capture nuanced, context-specific factors that shape flood vulnerability, providing a more holistic and accurate assessment.
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Increased Community Ownership and Engagement: The collaborative nature of the mapping exercise empowers community members, fostering a sense of ownership and investment in the flood risk management strategies that are ultimately developed.
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Targeted and Responsive Interventions: The spatially explicit visualization of flood risk, combined with community input, enables the design of targeted, context-appropriate interventions, such as the strategic placement of SUDS, that address the unique needs of different neighborhoods.
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Enhanced Resilience and Adaptive Capacity: The participatory approach builds upon the inherent resilience and adaptive capacity of local communities, strengthening their ability to anticipate, respond to, and recover from flood events.
By embracing a participatory mapping approach, urban communities can move towards a more inclusive, equitable, and effective model of flood risk management, better positioning themselves to confront the growing challenges of climate change and urban flooding.
Conclusion: The Path Forward
As the frequency and intensity of urban floods continue to rise, it is crucial that we adopt innovative, collaborative approaches to flood risk management. The integration of participatory mapping, which leverages local knowledge and community engagement, offers a promising avenue to enhance the resilience of informal settlements and other vulnerable urban areas.
We encourage readers to explore the Joint Action for Water website to learn more about community-driven initiatives and advocacy strategies in the water and sanitation sector. By working together and amplifying the voices of those most impacted, we can build more equitable and sustainable cities that are better prepared to withstand the threats of urban flooding.
