Urban planning and nature-based solutions, keys for reducing flood risk in Panama
By Haris Sanahuja, Juliana Castaño-Isaza, Carolina Rogelis, and Alessandra Treuherz
Panama City has tripled in size during the last 25 years as a result of rapid and unplanned urbanization. Its geographic location, combined with a lack of adequate land use planning, deficient drainage systems, and weak local governance, all make it a city highly exposed and vulnerable to the impact of floods and rising sea levels. This scenario implies a major challenge for the socio-economic development and resilience of this city of two million inhabitants.
Urban expansion, characterized by landfilling and construction in mangrove areas, has aggravated the degradation and loss of the Panama Bay RAMSAR site. Mangroves play a key role in reducing floods and protecting coastlines against waves, rising sea levels, and coastal erosion. In just fifteen years, between 2000 and 2015, mangrove coverage in the Tocumen basin has been reduced by 60% . These degradation processes have caused a significant rise in the frequency and impact of floods in the watersheds and coastal areas, generating the risk conditions that have already been evidenced in other basins of the city, such as the Juan Díaz river basin.
With the support from the World Bank and the Global Facility for Disaster Reduction and Recovery (GFDRR), the Municipality of Panama carried out a strategic flood risk assessment of the Tocumen river basin, located in the eastern part of the city. In this area, a development pole with key infrastructure has consolidated, including the Tocumen International Airport, the Pan-American Highway, and Line 2 of the city's metro system.
The assessment identified a range of possible interventions, including nature-based solutions (NbS) such as the conservation and restoration of mangroves and riparian vegetation, the recovery of natural channel shapes and routes, and the creation of urban parks with native species.
Three scenarios for the Tocumen River basin
Business-as-usual scenario: Foresees the continuation of uncontrolled filling in the coastal wetland areas due to urban expansion and the consequent degradation and loss of existing mangroves and wetlands.
Planned scenario: Considers applying the Municipality’s draft District Plan´s urban regulations, which includes control criteria for landfilling coastal wetland areas through a plan to preserve the current mangrove cover.
Optimum scenario: Considers substantial additional coastal and riparian floodplain conservation efforts, along with the ecological restoration of a diverse and resilient mangrove community.
The study highlights the following main findings:
If the current development pattern continues along the city’s coastal floodplain, coupled with sea-level rise and increased rainfall intensity resulting from climate change, flood risk in the basin will increase, particularly for the Tocumen International Airport and the neighboring community of Don Bosco. Considering climate change under the business-as-usual scenario, total annual losses due to floods will increase 750% by 2050 .
Smart and optimum scenarios, which include conservation and restoration measures for coastal and riparian floodplains, would mitigate the impacts of future planned developments in the basin.
There are clear benefits associated with the conservation and restoration of coastal wetlands for flood risk mitigation , and currently undeveloped floodplains in the basin as sites for water storage, recreation, and education.
It is important to note that nature-based solutions alone will not be sufficient for effective flood risk reduction. In order to achieve adequate levels of resilience to face climatic events such as heavy rains, storms, or rising sea levels, a comprehensive approach will be required that also includes other structural and non-structural risk management measures, where coastal planning plays a critical role.
In this context, the District Plan’s implementation, together with the flood risk mitigation proposals identified in this study, are essential for the sustainability and climate resilience of planned investments and urban development in this strategic area of Panama City.