The reservoirs had spilled 1,196,741 acre feet of water during the recent rains. "We have to think about planning for the future.
Reservoirs are normally designed for the heaviest rains in 200 years or 1,000 years," the head of Sri Lanka's irrigation agency G G Godaliyadda said.
"But we expect only one such event at a time. But this time we had two heavy rains in quick succession. This has to be taken into account in our hydrological studies."
Sri Lanka experienced two bouts of heavy rains in January with officials saying that rainfall from December 15, 2010 through January 2011 was three to four times the normal in many areas.
Irrigation minister Nimal Siripala de Silva says larger exit gates and canals may have to be build for all reservoirs and planned projects may also have to be re-designed to account for new hydrological data.
"As a long-term