Chilika Lake - Hydrology

Hydrology

Three hydrological subsystems control the Hydrology of the lake. The land based system comprises distributaries of the Mahanadi River on the northern side, 52 river channels from the western side and the Bay of Bengal on the eastern side. Two of the three southern branches of the Mahanadi River that trifurcates at Cuttack, feed the lake. 61% (850 cubic metres per second (30,000 cu ft/s)) of the total fresh water inflow into the lake is contributed by these two branches.

The second drainage system which is non–perennial accounts for 39% (536 cubic metres per second (18,900 cu ft/s)). The important rivers of this drainage system are the Kansari, the Kusumi, the Janjira and the Tarimi rivers. The annual total surface freshwater input to the lake is estimated to 1.76 cubic kilometres (1,430,000 acre·ft) including direct precipitation over the lake contributing 0.87 cubic kilometres (710,000 acre·ft) All the inland river systems disgorge an annual flow of about 0.375 million cubic metres (304 acre·ft) of freshwater which is estimated to carry 13 million metric tons of silt into the lake. On the north east a channel connects the lake to the Bay of Bengal.

A tropical monsoon climate prevails over the drainage basin area of the lake. The lake experiences South–west and North-east monsoons during June to September and November to December respectively with average annual rainfall of 1,238.8 mm (48.77 in), with 72 rainy days. The maximum temperature of 39.9 °C (103.8 °F) and minimum temperature of 14 °C (57.2 °F) have been recorded. The wind speed varies from 5.3 to 16 metres (17 to 52 ft)/hour with southerly and southwesterly direction due to the influence of the South–west monsoon and from north and north easterly direction during the rest of the months.