Risk map from Cyclone Ditwah

Where to prepare before the next flood, by DS division: Ditwah SOS requests, four past satellite flood maps and DMC landslide warnings since 2020.

Show

Risk classDitwah hotspots, silent areas, new and repeat riskDitwah SOSHow concentrated requests were, against other divisionsPast floodsHow many of 4 mapped floods covered 5% or moreLandslidesDays at DMC red (evacuate) level since 2020

SOS clusters (~2 km)

Legend

Ditwah hotspot · 41 divisions. Many SOS requests, in a division with a flood or landslide history or hit by Ditwah. Pre-position boats, teams and shelters here.

Hit but silent · 130 divisions. Ditwah flooded 15% or more of it, or the DMC issued a red landslide warning, yet very few SOS requests came in. Reach people through GN officers, SMS and local contacts.

New risk shown by Ditwah · 6 divisions. Many SOS requests but little history in the satellite flood maps, often from urban drainage. Update local risk plans.

Repeat hazard · 37 divisions. Flooded repeatedly or often warned for landslides, but quieter during Ditwah. Keep on the preparedness list.

Lower or no signal · 126 divisions. No strong signal in these sources. This does not mean there is no risk.

SOS requests are shown only as relative levels and ~2 km clusters, never as numbers or a household's location.

Divisions

Tap a division on the map, or pick one here, to see its flood and landslide history and how it fared in Ditwah.

How to read this

Ditwah SOS: requests made to FloodSupport.org from 28 to 30 November 2025; a little over half had a location good enough to place in a division. Each division gets a level from None to Very high, from requests per km² ranked against other divisions. Places with few people or no mobile data send fewer requests, so a low level is not the same as being safe.

Past floods: satellite flood extents from UNOSAT and Copernicus EMS, with permanent water removed (Cyclone Ditwah floods, Nov–Dec 2025; South-west monsoon floods, May–June 2024; North-east monsoon floods, Dec 2024; East coast floods, Dec 2014–Jan 2015). Clouds and the areas each satellite surveyed limit them, so flash floods and urban drainage flooding are often missed.

Landslides: DMC landslide early-warning levels per division from 2020-07 to 2026-10, parsed by nuuuwan/lk_dmc_landslides. Warnings show where landslides were expected, not where they happened.

What Ditwah taught us: many of the divisions with red landslide warnings, in the hills of Kandy, Matale, Nuwara Eliya and Badulla where most people died, sent very few SOS requests. Help must reach these places in other ways: Grama Niladhari officers, SMS, and local focal points who report for their neighbours.

The classes are a planning aid built from these sources, not an official hazard zoning. Use them alongside NBRO landslide zonation and Irrigation Department flood maps.