The Irrigation Department has warned of possible flooding in nine Divisional Secretariat Divisions after eight spill gates of the Deduru Oya Reservoir were opened on Thursday.
Water is being released into the Deduru Oya at 16,500 cubic feet per second, the department said. Two more gates were opened because of heavy rainfall in the upper and middle parts of the river basin, bringing the number of open gates to eight.
The department said water levels in the river have risen close to flood level. It warned that people living in low-lying areas along the river valley could be affected in the Divisional Secretariat Divisions of Wariyapola, Nikaweratiya, Mahawa, Kobeigane, Bingiriya, Pallama, Chilaw, Arachchikattuwa and Rasnayakapura.
The amount of water released could increase depending on how much flows into the reservoir, the department said. It urged residents downstream and motorists using roads in the affected areas to stay vigilant, and asked disaster management authorities to take the necessary precautions.
The department also said eight spill gates of the Rajanganaya Reservoir were open, releasing water into the Kala Oya at 7,884 cubic feet per second.
Background
A spill gate is a controlled opening in a reservoir that lets surplus water pass downstream when the reservoir is near its full level. Opening the gates is a routine way of keeping the structure safe during heavy rain, but it increases the flow in the river below, which can reach flood level if the inflow keeps rising.
The Deduru Oya flows through the North Western Province to the sea near Chilaw. Most of the Divisional Secretariat Divisions named in the warning lie in the Kurunegala and Puttalam districts. The Rajanganaya Reservoir is in the Anuradhapura district, and the Kala Oya flows from it through the North Central and North Western provinces.
The Irrigation Department publishes the status of major reservoirs and issues flood warnings for river basins, while the Disaster Management Centre coordinates the response of local authorities.
What it means
Residents of the nine divisions, particularly those living close to the river, may see water levels change quickly if the department opens more gates or if rain continues in the catchment area. The department has asked people to stay alert and to follow instructions from local officials.
Drivers on roads that cross or run beside the river are advised to take care, as roads in low-lying areas can be covered by water at short notice. Anyone who needs help during a flood can call the Disaster Management Centre emergency hotline on 117.
People with relatives in the affected areas, including Sri Lankans abroad, can check the Irrigation Department and the Disaster Management Centre for further updates, as the situation depends on the rainfall in the coming hours.
