- 17th June 2020
- Posted by: Emilia Gates
- Category: Projects
Location: Panama City, Panama
Client: The World Bank
We worked with The World Bank and the Municipality of Panama City to investigate the mechanisms, causes and risks of flooding in the rapidly urbanising Tocumen catchment. We then modelled alternative futures based on nature based solutions and hybrid solutions which combine green and grey infrastructure.
The catchment of the River Tocumen, on the east of Panama City, has undergone rapid urbanisation in recent decades. This has resulted in a loss and degradation of natural habitats including deforestation in the steep upper catchment, urbanisation in the fluvial floodplains and most recently a rapid loss of mangroves due to land-filling and raising for coastal property developments. This has contributed to an increase in flood risk from fluvial, pluvial and coastal sources, with eight deaths and c. 13,000 people impacted by recent floods.
Spatial planning policies and laws have not kept up with the transition of the city to a regional and international hub, with a lack of adequate zoning, building control and drainage contributing to the flood risk. Flood risk was predicted to increase significantly, including to the international airport, as a result of land use, climate change and sea-level rise.
The study developed an integrated hydraulic model of coastal, fluvial and pluvial flood sources, supported by new analysis of sea-level rise, rainfall intensity and land use in the catchment and wider city.
In parallel, the evolution of the river and coastal systems over recent decades was analysed. This identified that there are opportunities for mangroves to regenerate and to provide a valuable service protecting the coastline from erosion. The study also showed that in urban areas they are exhibiting signs of stress, meaning that they do not provide the level of protection offered by a healthy system.
Three future scenarios for development of the city were developed;
- implementation of the city’s new district plan
- a scenario based on restoration of natural floodplain and mangroves systems to provide enhanced flood protection. This demonstrated that nature-based solutions have the potential to mitigate many of the impacts of climate change.
The study made recommendations for all sectors involved in or able to influence flood risk management, including spatial planners, coastal and river engineers, disaster risk managers, developers, ecologists and the airport authorities.
Opportunities were identified in two currently undeveloped floodplain areas to both optimise their topography to store and reduce flood peaks, but also to provide space for recreation and high-quality development zoned on higher ground.
In this way, the study enhances the Municipality’s evidence base to support their emerging district plan. Capacity building training was delivered to a wide range of stakeholders, and used to develop a training session at the 2020 Understanding Risk CentroAmérica (URCA 2020) conference.
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