An estimated 2.3 million people – more than half of them women – were living in areas flooded by Cyclone Ditwah that struck Sri Lanka on 28 November.

New geospatial analysis from the United Nations Development Programme (UNDP) shows floodwaters from the cyclone inundated more than 1.1 million hectares – almost 20 percent of the country’s land area – and caused significant damage to homes, infrastructure and essential services.

The analysis, which draws from disaster related data from the Government of Sri Lanka, provides a nationwide picture of the cyclone’s impact, which is being termed as one of the worst flooding disasters to hit Sri Lanka in decades.

Over half of the people in the flooded areas were living in households already facing multiple vulnerabilities before the cyclone, including unstable income, high debt, and limited ability to cope with disasters. Under these conditions, even moderate shocks can turn into long-lasting setbacks.

The floodwaters reached nearly 720,000 buildings, about one in every twelve buildings in the country. Over 16,000 kilometres of roads, enough to circle the island’s coastline more than twelve times, were exposed to flooding. Similarly, over 278 km of railway tracks and 480 bridges were located in flooded areas, the statement said.

“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, with over 60% of all exposed people living in just two districts (Colombo and Gampaha). Many in affected areas across the country live in high-risk, disaster-prone areas, requiring a permeant solution. This concentration of exposure is placing heavy 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 said.

In the country’s hilly inland, the cyclone triggered around 1,200 landslides. These events can isolate at-risk communities by disrupting access to essential services such as health care and slowing rescue operations.

“Cyclone Ditwah is a stark reminder of how fast compounding crises can unfold,” said Devanand Ramiah, Chief of Crisis Readiness, Response, and Recovery at UNDP’s Crisis Bureau.

Working closely with the national authorities and partners, UNDP is calling for scaled-up early recovery support to help communities get back on their feet. This includes 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 a slow but steady recovery underway, Sri Lanka cannot shoulder more debt to cover the costs of a rebuild from this massive natural disaster”, said Azusa Kubota. “International partners must step up with affordable financing and innovative instruments that enable a rapid recovery and rebuilding with greater resilience, without the country falling off the debt cliff. UNDP with the UN family is working with government, our partners and communities, to support those most affected through immediate relief and early recovery efforts. The ‘rebuild stronger and better’ is essential and will take time.”