Will Kolonnawa flood in the next hour?

Kolonnawa flood risk right now: Alert. This is an estimate based on the Nagalagam Street gauge on the Kelani Ganga (2.8 km away), which read 4.4 ft as of Tue, 27 Oct, 2:10 am (Sri Lanka time). In the next hour the Kelani Ganga at Nagalagam Street could rise to about 4.6 ft (4.4–4.8 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 Kolonnawa worked out?

From the nearest river gauge ({gauge}, 2.8 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 Kolonnawa flooding?

Kolonnawa, Colombo

Kolonnawa flood risk right now: Alert. This is an estimate based on the Nagalagam Street gauge on the Kelani Ganga (2.8 km away), which read 4.4 ft as of Tue, 27 Oct, 2:10 am (Sri Lanka time).

Reading at 2:10 am · 35 min ago

Alert

4.4 ft

Next hour

Rising with the tide, about the same once the tide is allowed for

Next 24 hours

Risk stays high

Move valuables up, charge your phone

Experimental estimate. There is no river gauge in Kolonnawa; this uses Nagalagam Street, 2.8 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 4.4 ft, rising (at alert level)
55 mm of rain in the last 24 hours
Water in Kolonnawa 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 · 2.8 km away

Alert4.4 ft2:10 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 Kolonnawa right now?

Your answer helps us check our warnings. It is anonymous: we save only the town and your answer. Nobody sees single answers; we show only totals of 3 or more.

When? (optional)

Is this right?

Each answer helps us improve the forecast for your area.

Based on: Nagalagam Street gauge on the Kelani Ganga, 2.8 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 Kolonnawa

Heavy rain in the last 24 hours (109 mm). Moderate rain expected early this morning, about 19 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.

Sea level at the Kelani mouth is rising (reading 1:15 am). Canal levels: CUrW / SLLDC (pub.curwsl.org)

How water drains here

Water here drains into the Kolonnawa canal and out to the Kelani through the North Lock pumps and gates at Nagalagam Street and the Gothatuwa gates. When the sea is high or the Kelani is high the canal cannot empty, so heavy rain plus high tide or a high river slows draining.

The canals here are higher than usual right now, so they drain more slowly. This is context, not a flood warning.

Colombo canals explained

Canal levels now · Kolonnawa canal basin

Sea at the Kelani mouth
2.1 ft above sea level
Reading 1:15 am
Wellampitiya NNot reporting

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 Kolonnawa were partly or fully under water:

Meethotamulla2016
Kolonnawa2016
Dematagoda2016
Gajabapura2016
Dahampura 12016
Kuruniyawatta2016, 1989
Wanathamulla2016
Wijayapura2016
and 13 more nearby

Flood help and phone numbers

Common questions

Is Kolonnawa flooding now?: Kolonnawa flood risk right now: Alert. This is an estimate based on the Nagalagam Street gauge on the Kelani Ganga (2.8 km away), which read 4.4 ft as of Tue, 27 Oct, 2:10 am (Sri Lanka time).
Will Kolonnawa flood in the next hour?: Kolonnawa flood risk right now: Alert. This is an estimate based on the Nagalagam Street gauge on the Kelani Ganga (2.8 km away), which read 4.4 ft as of Tue, 27 Oct, 2:10 am (Sri Lanka time). In the next hour the Kelani Ganga at Nagalagam Street could rise to about 4.6 ft (4.4–4.8 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 Kolonnawa worked out?: From the nearest river gauge ({gauge}, 2.8 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.