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What happened, where and when?
On 11 October 2024, the Meteorological Department forecasted persistent showery conditions in the southwestern part of Sri Lanka due to an atmospheric disturbance near the island. Heavy showers exceeding 150 mm, or thundershowers, were anticipated in several provinces, increasing the risk of flooding in vulnerable areas.
In response to the forecast, at 2:00 PM on 11 October 2024, the Department of Irrigation issued an early flood warning for the Attanagalu Oya area in Gampaha District and surrounding regions, as heavy rainfall continued in the river basin. By the morning of 12 October 2024, the Attanagalu Oya had reached primary flood levels at Dunamale. In addition, the Kelani River in Colombo District, the Ging River in Galle District, and the Kalu River in Kalutara District also reached flood levels, triggering additional alerts from the Department of Irrigation. These warnings were issued due to unstable atmospheric conditions, which continued to exacerbate the situation. The highest recorded rainfall in the affected regions was 117 mm in Eheliyagoda, 114 mm at Halvatura Estate, and 105.5 mm in Hanwella (Colombo and Gampaha districts).
By 13 October 2024, the Department of Irrigation escalated the warnings, issuing major flood alerts to people living around Attanagalu Oya in Gampaha District, where the situation had worsened. The district continued to experience heavy rainfall and reported the highest number of affected residents, totaling 68,672.
As of 15 October 2024, the Disaster Management Centre (DMC) reported that approximately 154,782 people from 39,522 families had been affected by the adverse weather conditions. Out of these, 10,361 people from 2,433 families were being sheltered in 80 safe locations.
Gampaha District remained the most severely impacted, with 78,281 affected residents [01].
The following districts have experienced the most significant damage and people affected;
A 34-year-old man drowned in Kelanimulla, Mulleriyawa, located in Colombo District. The adverse weather has also claimed three lives as of 15 October 2024 [02]. According to the Disaster Management Centre (DMC), the severe weather caused complete destruction of one house and partial damage to 321 houses.
Government and Organizational Support:
On 13 October 2024, the Government instructed the Secretary of Defense to take immediate steps to ensure the safety of people in areas affected by the extreme weather. In response, the Ministry of Finance allocated 50 million rupees for relief efforts. The Sri Lanka Navy deployed six flood relief teams to various locations across Gampaha and Colombo districts to conduct urgent search and rescue operations. Due to the extreme weather, all schools within the Gampaha and Colombo educational zones were closed on 14 and 15 October 2024, with many schools inundated by floodwaters.
Meteorological Warnings:
The sea areas off the coast from Puttalam to Hambantota, via Colombo and Galle, are expected to be very rough, with gusty winds reaching speeds of 60 to 70 km/h. Naval and fishing communities have been advised not to venture into these waters until further notice.
The National Building Research Organisation (NBRO) issued a landslide warning for nine districts in the western and southwestern provinces, including Colombo and Gampaha, due to ongoing heavy rainfall. Residents, particularly those in mountainous areas, near artificial cut slopes, and along roads in the designated Divisional Secretariat Divisions (DSDs), have been advised to remain vigilant [03].
The increased intensity of rainfall, now exceeding 100 mm per hour, has triggered flash floods in several areas. The Department of Irrigation has also warned that as water continues to flow from higher elevations, water levels in the rivers are expected to rise further, posing a high risk of flooding in the low-lying areas of Gampaha and Colombo districts.