Will Dematagoda flood in the next hour?

Dematagoda flood risk right now: Alert. This is an estimate based on the Nagalagam Street gauge on the Kelani Ganga (1.7 km away), which read 4.5 ft as of Tue, 27 Oct, 3:07 am (Sri Lanka time). In the next hour the Kelani Ganga at Nagalagam Street could fall to about 4.4 ft (4.3–4.7 ft). This is a forecast for the river, not an official warning, and streets can flood before the river reaches a flood mark.

How is the flood risk for Dematagoda worked out?

From the nearest river gauge ({gauge}, 1.7 km away), recent and expected rain, the gauge's forecast and any official warning. It is an estimate for the town, not an official warning, and streets can flood before the river reaches a flood mark.

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.

Is Dematagoda flooding?

Dematagoda, Colombo

Dematagoda flood risk right now: Alert. This is an estimate based on the Nagalagam Street gauge on the Kelani Ganga (1.7 km away), which read 4.5 ft as of Tue, 27 Oct, 3:07 am (Sri Lanka time).

Reading at 3:07 am · 28 min ago

Alert

4.5 ft

Next hour

River falling

Next 24 hours

Risk stays high

Move valuables up, charge your phone

Experimental estimate. There is no river gauge in Dematagoda; this uses Nagalagam Street, 1.7 km away, plus rain at the town and official warnings.

Call 117 Colombo DMC office

Details

How this estimate works

· Starts from the river gauge's own level and forecast, the same as the gauge page.
· Heavy rain here (50 mm in 6 hours or 100 mm in 24 hours) raises it by one step, never more.
· Your own street level, if you set one, and official warnings can raise it further.
· It never says flooding is happening: only a measurement can show that.

Why

Irrigation Department has issued a flood warning for Kelani Ganga
Very heavy rain here: 109 mm in 24 hours. At this much rain, low streets and canal banks in this area often get water
Kelani Ganga at Nagalagam Street is 4.5 ft, rising (at alert level)
54 mm of rain in the last 24 hours
Water in Dematagoda drains through canals into the river. When the river is high, rain can stay on the lowest ground near them.

Your river

Nagalagam Street

Kelani Ganga · 1.7 km away

Alert4.5 ft3:07 am

Low ground near the canals

Street water likely in low spots here

109 mm of rain in the last 24 hours

Low-lying lanes beside the canals usually get water first; most streets stay dry.

An early heads-up from rain totals, often wrong; it doesn't mean your street is flooding.

Where the rain numbers come from: read the research

Is there water in your street in Dematagoda right now?

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Based on: Nagalagam Street gauge on the Kelani Ganga, 1.7 km away

Set your street's flood level

At what Nagalagam Street reading does water reach your street? Saved on this device only, never sent anywhere.

Rain in Dematagoda

Heavy rain in the last 24 hours (109 mm). Moderate rain expected early this morning, about 17 mm in the next 24 hours.

mm per hour

Tap or hover a bar to see that hour.

Rain map

It is around high tide now. Canals drain slowest for the next hour or so. Next high tide around 3:03 pm.

Predicted tide; times can be off by up to an hour.

How water drains here

Water here drains through the Dematagoda and St Sebastian canals and Beira Lake towards the Mutwal tunnel and the Kelani mouth, which rise and fall with the tide. Heavy rain at high tide, or a high Kelani, slows draining.

Colombo canals explained

Canal levels now · North canals (Dematagoda, St Sebastian, Mutwal)

Sea at the Kelani mouth
Reading 1:15 am
Sedawatta Bridge DSNot reporting
Reading 1:15 am
OrugodawattaNot reporting
Reading 1:15 am

River map

GaugeReservoirTap a gauge or reservoir for details.

Reservoirs upstream

Official flood map

In the Irrigation Department's maps of past floods (Kelani Ganga 2016 major flood, 1989 critical flood), these Grama Niladhari divisions around Dematagoda were partly or fully under water:

Orugodawatta2016, 1989
Dematagoda2016
Wadulla2016, 1989
Meethotamulla2016
Kuruniyawatta2016, 1989
Veheragoda2016, 1989
Sedawatta2016, 1989
Bloemendhal2016
and 9 more nearby

Flood help and phone numbers

Common questions

Is Dematagoda flooding now?: Dematagoda flood risk right now: Alert. This is an estimate based on the Nagalagam Street gauge on the Kelani Ganga (1.7 km away), which read 4.5 ft as of Tue, 27 Oct, 3:07 am (Sri Lanka time).
Will Dematagoda flood in the next hour?: Dematagoda flood risk right now: Alert. This is an estimate based on the Nagalagam Street gauge on the Kelani Ganga (1.7 km away), which read 4.5 ft as of Tue, 27 Oct, 3:07 am (Sri Lanka time). In the next hour the Kelani Ganga at Nagalagam Street could fall to about 4.4 ft (4.3–4.7 ft). This is a forecast for the river, not an official warning, and streets can flood before the river reaches a flood mark.
How is the flood risk for Dematagoda worked out?: From the nearest river gauge ({gauge}, 1.7 km away), recent and expected rain, the gauge's forecast and any official warning. It is an estimate for the town, not an official warning, and streets can flood before the river reaches a flood mark.
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.

Kelani Ganga · Sources: Department of Irrigation gauges, Open-Meteo rain, Disaster Management Centre warnings.