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Rising Waters, Rising Hopes: Shaping Resilience in São Tomé and Príncipe Through Flood Risk Analysis

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In the heart of the Gulf of Guinea, the island nation of São Tomé and Príncipe (STP) faces a paradox: the very waters that cradle its economic lifeline also harbor the seeds of vulnerability. This small archipelago grapples with the threat of floods that continue to worsen under a changing climate.

But how does a nation so intimately tied to the ocean’s bounty brace itself against the very element that sustains its rich fisheries, vibrant biodiversity, agricultural exports, and tourism industry? This is the question at the heart of the West Africa Coastal Areas Management Program (WACA)’s efforts to promote resilience and balance vulnerability and hope. Part of the answer lies in the application of cutting-edge flood risk analysis and long-term prediction tools to inform country-specific solutions, which we’re happy to share in our new report:  Island Insights: Surging Seas and Increasing Rains—Analyzing Flood Risks in São Tomé and Príncipe, District by District. We’ll showcase a few of the report insights in this blog.

STP is home to about 228,000 people, with almost 45% of the population living below the international poverty line for lower-middle-income countries. Influenced by the country’s steep topography, its people and infrastructure are nestled along the islands’ coastline and waterways. This proximity to the water’s edge, while picturesque, exposes citizens to the whims of nature, as recent events can attest.

Between December 2021 and February 2022, the island of São Tomé experienced a sequence of severe weather events, including record-breaking rainfall that led to severe flooding and landslides. Several lives were lost, the capital city’s central area was cut off, more than 670 hectares of farmland were destroyed, and public drinking water and sanitation systems were severely damaged. According to Saotomean authorities, recovering from these events will cost $37.5 million—about 7% of the country’s GDP in 2022. Estimates suggest a flood like this will occur, on average, once every 20 years.

Disasters like this feed news stories, but floods affect the livelihoods of Saotomean communities every year. The quiet community of Praia Cruz on São Tomé Island views the frequent, turbulent storms as a threat to its existence. Ângela dos Ramos, a local young fisherwoman, says that flooding has heavily impacted her community: “The beach is not the same. It has changed.” The community of Praia Abade on Príncipe Island has also observed an intensification of flooding threats. Irma Lourenço, a 48-year-old fish trader, says she is losing sleep due to the fear of losing everything. Over time, this house started to have problems,” she says. “The rain and sea come in.” Read some further stories of the lives of Santomeans in Voices of WACA in São Tomé and Príncipe.

Photos: World Bank Ângela dos Ramos (in yellow) and Irma Lourenço (pictured below) are acutely aware that flood risk in their country is intensifying. Photos: World Bank

Understanding the problem

The World Bank recently carried out an extensive national flood risk assessment to quantify the growing risk that São Tomé and Príncipe will face due to climate change. The assessment used high-resolution flood hazard data for the present climate (2020) and two future climate scenarios (for 2050 and 2080) based on the projected IPCC scenario SSP3-7.0 and assuming no additional climate policy. The hazard data considered flooding from rivers as well as coastal flooding mechanisms to evaluate flood risks and calculate annual expected losses under present and future climates if no action is taken.

The risk assessment found a significant increase of overall risk under future climate conditions. Projections show the expected yearly losses due to floods to be 1.9% of STP’s GDP in 2020, 2.8% in 2050, and up further to 4.1% in 2080. The overall flood risk more than doubles within 60 years, even without taking additional exposures into account.

Presently, floods affect almost 18,500 people each year, on average. This number is expected to rise by 25% (to 23,000) in 2080, with the subdistricts of Malanza and Santa Catarina most affected, with 33% and 41% of their total populations being affected, respectively.

Nasikiliza Santa Catarina with present (blue) and future flood extents (orange: 2050; red: 2080). Source: World Bank

This study expresses what most Saotomeans already know. The picture is concerning, but it can also be a source of hope and driver for change. A spatially explicit quantification enables informed decisions on retrofitting initiatives, new flood defenses, construction prohibitions, and community relocations. It also helps STP prioritize resources and craft a common vision for action and can even serve as the foundation for more detailed sector-level analysis.

nasikiliza Summary of the World Bank flood risk report findings

Frequent flood events are the main driver of flood risk, with the most vulnerable houses—wooden constructions on stilts—often located in the floodplains of rivers and creeks or close to the ocean shore. The areas are extremely sensitive to climate change, and while vulnerable communities can withstand these shocks today, they may not be able to in future.  

The Government of São Tomé and Príncipe is poised to harness insights from the report, address sector-specific impacts, and strategically allocate funds for maintenance and fresh investments. Ongoing activities under the WACA Program and proactive collaborations between the government, NGOs, and communities will boost local preparedness measures, accelerate flood protection investments, and enhance risk communication initiatives, helping limit an increase in flood risk and paving the way to flood resilience.  Arlindo de Carvalho, WACA Coordinator for STP, reiterates the importance of collective action across all sectors: “To build upon WACA’s progress in STP, we must promote risk behavior changes, fortify coastal policies, and secure enduring commitments from communities and government. The increasing intensity and frequency of extreme events assailing our coastal communities underscore the urgency to extend our efforts to all vulnerable areas.”

In the short term, STP will need international support and flood resilience investments to catalyze local development pathways that are less dependent on foreign aid, such as increased tourism spending. For the country to succeed, local and foreign stakeholders need to rally behind STP —a country as endearing as it is exposed—and play their part in securing its future.

This pioneering national flood risk study for São Tomé and Príncipe sheds light on the potential impacts of climate change. Its findings bolster the WACA Program’s vital work and reinforce the collective push by the government, NGOs, and communities towards enhancing preparedness, expediting flood protection, and improving risk communication. Above all, the study provides hope, which must match the rising waters.

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