The Department of Irrigation opened spill gates at the Deduru Oya, Lunugamvehera and Rajanganaya reservoirs on Friday morning as heavy rain continued to swell catchments across most of Sri Lanka.
Four spill gates of the Deduru Oya Reservoir have been opened by three feet each, releasing 8,400 cubic feet of water per second into the Deduru Oya, the Department said in a statement.
At the Lunugamvehera Reservoir, six spill gates have been opened: two raised by four feet each and four opened by eight feet each, discharging 2,915 cubic feet per second. The Department urged communities and water users along the banks of the Kirindi Oya to remain vigilant.
Six sluice gates of the Rajanganaya Reservoir have also been opened — four raised by two feet each and the remaining two opened by three feet each — releasing 4,542 cubic feet per second.
H.M.P.S.D. Herath, Director of the Water Management Division, advised residents in downstream areas to stay alert.
The Department of Meteorology said showery conditions are expected to continue over the island during the next few days because of a low-level atmospheric disturbance near Sri Lanka. Showers or thundershowers are likely at most places after 1pm on Friday, with falls above 100mm possible in Western, Sabaragamuwa, Central, Uva, North-Western and North-Central provinces and in Galle, Matara and Mannar districts. Misty conditions are expected at some places in Central, Sabaragamuwa and Uva provinces and Kurunegala District during the early hours.
The Department on Friday afternoon issued two formal Amber advisories. A severe-lightning advisory issued at 11am covers the Western, Sabaragamuwa, Central, Southern, Uva, North-Western, Northern and North-Central provinces and the Trincomalee district, and remains in effect until 11.30pm. A separate heavy-rainfall advisory issued at noon flags falls above 100mm in the Western, Sabaragamuwa, Central, Uva, North-Central and Northern provinces and in Galle, Matara and Kurunegala districts, in force until 8.30am on Saturday. The public has been urged to take precautions against lightning, strong winds and flooding.
The discharges follow Wellawaya–Kirindi Oya flooding on May 8 caused by Lunugamvehera releases earlier in the week, and continue an intense rainfall pattern the Met Department flagged on Thursday with the same 100mm threshold. Lunugamvehera supplies the southern plains, and downstream districts including Tissamaharama and Hambantota face heightened flood risk when its gates are open.
Update — May 10: The Irrigation Department on Sunday morning said nine major reservoirs and five medium-scale reservoirs were now spilling as rainfall continued. Director of Irrigation and Water Management Engineer H.M.D.P.S.D. Herath listed Lunugamwehera (six gates, over 4,000 cfs into Kirindi Oya), Weheragala (six gates, more than 1,400 cfs into Menik Ganga), Rajanganaya (eight gates, over 9,300 cfs into Kala Oya), Deduru Oya (four gates, 5,500 cfs into Deduru Oya) and Alikota Ara (three gates, over 500 cfs into Kirindi Oya) among the spilling reservoirs. Authorities urged residents living downstream of these reservoirs to remain alert. The National Building Research Organisation also issued early landslide warnings on Sunday morning for the Passara, Badalkumbura and Wellawaya divisional secretariat areas in Badulla and Monaragala.
Update — May 11: The Irrigation Department said the count had risen to 12 major reservoirs and six medium-scale reservoirs — 18 in total — releasing water as the low-pressure system continued to feed heavy rainfall. The major reservoirs now spilling include Rajanganaya (Anuradhapura); Sorabora Wewa (Badulla); Wemedilla, Devahuwa and Nalanda (Matale); Lunugamvehera, Thissa Wewa, Weerawila, Yoda Wewa and Weheragala (Hambantota); Deduru Oya (Kurunegala); and Alikota Ara (Monaragala). The medium-scale list adds Thuruwila (Anuradhapura), Bomburuella (Badulla), Debara Wewa (Hambantota), Saddhatissa and Malinpotta (Monaragala) and Mailankulam (Vavuniya). Engineer Herath cautioned that release volumes could change with further rainfall and urged residents near reservoirs and in low-lying areas to follow advisories from the Irrigation Department, the Department of Meteorology and the Disaster Management Centre.
Update — May 12: Officials said 12 spill gates of the Rajanganaya Reservoir have been opened as a precautionary measure due to continuing adverse weather and a rapid rise in water levels in the North Central Province reservoir. Authorities urged downstream communities to exercise caution.
