Last Updated : 07 February 2023.
Sri Lanka is a tropical island country with an average annual rainfall of 900–5,000 mm, which provides 131,230 million m3 of freshwater annually. Zones in its southwest are the wettest, receiving over 2,000 mm/year, while northern (and some southeast) areas are considered dry zones with under 1,500 mm/ year. There are 103 river basins, and the largest river is the 335 km Mahaweli River, covering an area of 10,448 km2. Rivers in the wet zones contribute over 50% of the runoff despite covering only about one third of the land area. There are over 3,400 wetlands, which include ancient irrigation reservoirs, recently constructed multipurpose reservoirs, tanks and lakes.
State of water environment
- National Environmental Act No.47 (Outside source: FAO)
- Marine Pollution Prevention Act of No. 35 (Outside source: FAO)