An estimated 2.3 million people – more than half of them women – were living in areas flooded by Cyclone Ditwah, which struck Sri Lanka on 28 November. New geospatial analysis from the United Nations Development Programme (UNDP) shows that floodwaters inundated more than 1.1 million hectares – nearly 20 percent of the country’s land area – causing extensive damage to homes, infrastructure, and essential services.
The analysis, based on disaster-related data from the Government of Sri Lanka, provides a nationwide picture of the cyclone’s impact, now considered one of the worst flooding disasters to hit the country in decades.
Over half of the people living in the flooded areas were already facing multiple vulnerabilities before the cyclone, including unstable income, high debt, and limited capacity to cope with disasters. Under such conditions, even moderate shocks can lead to long-term setbacks.
Floodwaters reached nearly 720,000 buildings – about one in every twelve structures in the country. More than 16,000 kilometres of roads, enough to circle Sri Lanka’s coastline over twelve times, were exposed to flooding. Additionally, over 278 kilometres of railway track and 480 bridges were located in inundated areas.
“Cyclone Ditwah struck regions already weakened by years of economic stress,” said Azusa Kubota, UNDP Resident Representative in Sri Lanka.
The exposed population includes approximately 1.2 million women, 522,000 children, and 263,000 older persons. Over 60 percent of all affected people live in just two districts – Colombo and Gampaha. Many of those impacted reside in high-risk, disaster-prone areas, highlighting the urgent need for permanent solutions. This concentration of exposure is placing immense pressure on essential services.
“Where high flooding and high vulnerability overlap, recovery is likely to be slower and more costly. Early action in these locations is critical,” Kubota added.
In Sri Lanka’s hilly interior, the cyclone triggered around 1,200 landslides. These events have isolated at-risk communities, disrupted access to essential services such as health care, and slowed rescue operations.
“Cyclone Ditwah is a stark reminder of how quickly compounding crises can unfold,” said Devanand Ramiah, Chief of Crisis Readiness, Response, and Recovery at UNDP’s Crisis Bureau.
Working closely with national authorities and partners, UNDP is calling for scaled-up early recovery support to help communities rebuild. Priorities include restoring essential services, supporting affected households—particularly women, children, and older persons—repairing key transport and service-delivery infrastructure, and strengthening local systems for future climate resilience.
“After one of its worst economic crises, and with a slow but steady recovery underway, Sri Lanka cannot take on additional debt to shoulder the cost of rebuilding after this massive natural disaster,” Kubota said. “International partners must step up with affordable financing and innovative instruments that enable rapid recovery and resilient rebuilding, without pushing the country deeper into debt. UNDP, together with the UN family, is working with the government, partners, and communities to support those most affected through immediate relief and early recovery efforts. Rebuilding stronger and better is essential—and it will take time.”
