Protecting Antananarivo from floods with nature-based solutions

The challenge: protecting Antananarivo from increasing flood risk

More than 650,000 inhabitants of Antananarivo, Madagascar, are currently facing a diverse range of water-related issues, including pluvial floods and water pollution, which are particularly damaging to the city’s vulnerable communities.

In response, the Government of Madagascar has signed a Country Partnership Framework with the World Bank, which includes the implementation of the Integrated Urban Development and Resilience Project for Greater Antananarivo (PRODUIR).

This project required input from a range of experts to increase flood resilience and improve living conditions in Antananarivo’s low-income areas.

The solution: a comprehensive plan for flood risk reduction

Royal HaskoningDHV, along with lead research institute Deltares and partners BoschSlabbers, and Evolutis, carried out a comprehensive assessment and pre-feasibility study of different urban resilience adaptation strategies. These strategies were required to integrate both nature-based solutions and disaster evacuation planning to increase flood resilience and enhance living conditions in low-income neighborhoods.

Our work began with a comprehensive review of global best practices for the integration of nature-based solutions and evacuation measures. A full systems analysis further identified the existing challenges the geography of the region posed, and provided insight into Antananarivo’s water system and its connection to pluvial and fluvial flooding.

With this information, we were able to identify potential intervention sites along with the optimal structural and non-structural measures to create a robust resilience strategy.

Our plan included nature-based solutions like urban forests, retention ponds, and bioswales. It also factored in the technical design considerations for the implementation of these solutions, as well as maintenance, communication, and long-term monitoring and upscaling plans. 

We conducted scenario analysis to determine how these measures, integrated into a disaster evacuation plan, could address area challenges. We emphasized on-site and off-site refuges interconnected through an evacuation route network, forming a scalable network of nature-based solutions.

Finally, we performed a pre-feasibility assessment to guide stakeholders in implementing and scaling up these solutions for flood risk reduction and disaster evacuation.

The result: targeted interventions for a safer future and better living conditions

The targeted interventions, urban planning, and disaster risk management strategies outlined in our plan will strengthen the urban resilience of Antananarivo, and provide environmental and safety benefits to its 650,000 residents.

When executed, the plan should provide not only flood protection but also an enhancement to urban living conditions, thanks to the implementation of international best practices for green infrastructure.

If the project illustrates one thing, it’s the ability to address complex challenges with simple solutions that are community based and easy to implement and replicate. Central to this is education about the inherent power of nature-based solutions.

Find out more about the project in the i-report.