Will the Aththanagalu Oya at Dunamale rise in the next hour?

In the next hour the Aththanagalu Oya at Dunamale could rise to about 15.4 ft (15.3–15.6 ft). This is a forecast from the recent trend, the gauges upstream and rain, not an official warning.

What is the flood level at Dunamale?

The official marks for this gauge are alert 10.8 ft, minor flood 14.4 ft, major flood 18.0 ft. Alert means the river has reached the alert mark: move valuables up and charge your phone. Minor flood means water is spilling over low ground, and major flood means move to safety.

Where does this come from and how often does it update?

River readings come from the Department of Irrigation's gauges, roughly once an hour, and this page checks for new ones every minute. This site is independent and not an official warning service: follow the Disaster Management Centre and call 117 in an emergency.

Dunamale Aththanagalu Oya water level

As of Tue, 27 Oct, 3:15 am (Sri Lanka time), the Aththanagalu Oya at Dunamale was 15.4 ft, above the 14.4 ft minor flood level, and rising slowly.

In the next hour it could rise to about 15.4 ft (15.3–15.6 ft).

Official warning:

Rising Attanagalu Oya levels pose a flood risk in low-lying areas along the Attanagalu Oya and Uruwal Oya in nine named divisions; residents and motorists should exercise extreme caution.

Irrigation Department

Reading at 3:15 am · 30 min ago

Minor flood

15.4 ft

Next hour

Rising slowly

Next 24 hours

Could reach flood level in ~11 hours

Leave low areas near the river

The river is above minor flood level and could reach major flood level around 2 pm this afternoon (in about 11 hours).

Call 117 Gampaha DMC office

Details

Above minor flood level now and could reach major flood level around 2 pm this afternoon (in about 11 hours) (about 35% chance).

Published as 4.68 m (alert 3.3 m, minor flood 4.4 m, major flood 5.5 m)

In	Level	80% range	At
1h	15.4 ft	15.3 to 15.6	4:15 am
3h	15.5 ft	15.1 to 16.0	6:15 am
6h	15.6 ft	14.5 to 17.1	9:15 am
12h	15.6 ft	13.7 to 19.3	3:15 pm
24h	15.3 ft	12.4 to 21.0	3:15 am

Major flood (18.0 ft): possible, about 3 in 10, from about 2:15 pm

Local trend

+0.1 ft/h

Upstream avg

n/a (top)

Rain that fell: 0.0 mm in the last 3 hours, 98 mm in the last 24 hours at this gauge (heavy rain) (heavy for this river)
Rain forecast: 8.6 mm in the next 24 hours over the catchment (light rain). Forecast model estimate.

Satellite estimate of rain over the catchment: 5.0 mm in the last 6 hours, 119.4 mm in the last 24 hours (to 3:30 am). It can differ from the gauges. GSMaP data by Japan Aerospace Exploration Agency (JAXA)

· Part of the range is above the highest level this model has seen (12.5 ft); treat it as a rough guide.

How this is worked out
· Latest level at Dunamale and recent change. No gauge sits upstream of it (or none reports in step with it), so the catchment rain is its upstream signal.
· Forecast model estimate of catchment rain (Open-Meteo, area average over 4 grid cells above Dunamale): 70 mm modelled for the last 24 hours, 9 mm forecast for the next 24 hours, with ECMWF ensemble spread.
· The 1, 3, 6, 12, 24 hour steps use this gauge's own recent changes and the other gauges on the river (fitted to about 11 months of hourly readings, including the November 2025 Ditwah floods); where this was tested against 'level stays the same' it missed by less.
· The 6, 12, 24 hour steps read the rain the satellite measured over Dunamale's catchment (JAXA GSMaP, corrected for how it reads here), with rain beside the gauge and rain on the channels upstream timed separately (about 5 h from beside the gauge). Tested storm by storm it was closer than the version that reads the weather model's rain.
· Heavy rain upstream is part of the 1, 6, 12, 24 hour steps: rain that has fallen or is forecast over the catchment above Dunamale raises the level, and the top of the range allows for the heavier forecast rain. Tested storm by storm (leaving each storm out, Ditwah included) it was closer than the river's own trend alone.

Is this right?

Each answer helps us improve the forecast for your area.

Water level

How this river reacts to rain

Rain close to Dunamale shows up in the river in about 5 hours.
About 50 mm of rain over 24 hours, averaged over the catchment, has usually come before a rise of 1 ft or more.

Learned from 11 months of readings and satellite rain. A guide, not a forecast.

This gauge’s forecasts: the next hour is typically off by about 0.1 ft; 24 hours ahead, by about 1.7 ft (last 30 days, 25 checks).

When does Dunamale flood?

Flood warnings come mostly between October and November.

It’s October: the main flood season here. Worth checking levels daily after heavy rain.

Recent floods

26 Oct – 27 Oct 2026Minor flood
22 May – 23 May 2026Minor flood
14 May – 16 May 2026Minor flood
Biggest since 2022:27 Nov – 1 Dec 2025Major flood

Every day since 2022, year by year

Other stations

In the newsNews reports, not official.

RiverSource: Daily Mirror26 Oct, 7:31 pm (8 h ago)
Flood warnings issued for Kelani, Attanagalu Oya basins(opens the news site in a new tab)
The Irrigation Department has issued a minor flood warning for low-lying areas of the Kelani River Valley, covering the Divisional…
RiverSource: Newswire26 Oct, 7:10 pm (9 h ago)
Amber flood warning issued for low-lying areas of Kelani and Attanagalu river basins(opens the news site in a new tab)
The Department of Irrigation has issued Amber flood warnings for low-lying areas in the Kelani River and Attanagalu Oya basins…

Towns that depend on this gauge

Common questions

Is Dunamale flooding now?: As of Tue, 27 Oct, 3:15 am (Sri Lanka time), the Aththanagalu Oya at Dunamale was 15.4 ft, above the 14.4 ft minor flood level, and rising slowly.
Will the Aththanagalu Oya at Dunamale rise in the next hour?: In the next hour the Aththanagalu Oya at Dunamale could rise to about 15.4 ft (15.3–15.6 ft). This is a forecast from the recent trend, the gauges upstream and rain, not an official warning.
What is the flood level at Dunamale?: The official marks for this gauge are alert 10.8 ft, minor flood 14.4 ft, major flood 18.0 ft. Alert means the river has reached the alert mark: move valuables up and charge your phone. Minor flood means water is spilling over low ground, and major flood means move to safety.
Where does this come from and how often does it update?: River readings come from the Department of Irrigation's gauges, roughly once an hour, and this page checks for new ones every minute. This site is independent and not an official warning service: follow the Disaster Management Centre and call 117 in an emergency.