The volume of water being released from the Deduru Oya reservoir was widened twice on Saturday evening, ending with eight spill gates open and about 5,500 cubic feet per second going downstream, and landslide risk warnings were issued for eight districts later the same night.
The release, and how it moved
At around 6.20pm the Irrigation Department said six sluice gates had been opened by one foot each, discharging roughly 4,100 cusecs into the Deduru Oya, the Daily Mirror reported. The step was taken to control the volume of water entering the reservoir.
About two and a half hours later the department put the release at eight gates, again one foot each, and 5,500 cusecs, Hiru News reported in Sinhala. It warned that water levels in areas below the reservoir could rise as a result and told residents there to stay alert.
The Director of Irrigation (Water Management) asked people living downstream, particularly along the Deduru Oya itself, to watch for changes in river levels and to follow announcements issued by the Irrigation Department and disaster management authorities. The department cautioned that inflows and rainfall could both change, which would alter how much water is let out.
Landslide warnings
Landslide risk notices were issued for parts of Kandy, Nuwara Eliya, Badulla, Galle, Matara, Kegalle, Ratnapura and Monaragala districts because of the prevailing bad weather, Hiru News reported at about 9.10pm.
Second-stage warnings — a step up from the general notices — were issued for the Udadumbara divisional secretariat area in Kandy district and for the Walapane and Nildandahinna divisional secretariat areas in Nuwara Eliya district. The filing does not name the issuing agency, so this desk is not attributing the notices to a specific body.
Which release this is
Spill-gate bulletins at Deduru Oya read almost identically from one event to the next, and several distinct releases have been reported at this reservoir in the past fortnight. The event described here is the Saturday 7 November release: six gates and 4,100 cusecs in the early evening, rising to eight gates and 5,500 cusecs by about 8.50pm.
It is not the 4 gates and 2,800 cusecs opened on 2 November, which later widened to eight gates and 15,300 cusecs and halted Northern Line trains. A 4,100-cusec discharge at Deduru Oya was also reported in the Irrigation Department’s 5 November bulletin on reservoirs spilling island-wide; no filing states whether the rate held at that level in between.
