Irrigation in Tamilnadu
SOURCES OF IRRIGATION
Water is an important determinant factor of production of crops in agriculture sector. Intensive and extensive cultivation of land depend mainly on the availability of water. Medium and minor irrigation schemes are implemented in the state for augmenting the irrigation for agriculture. The various sources of irrigation are canals, tanks, tube wells, Open wells and springs. 
Canals (Including System Tanks)
Canals are the major source of irrigation in Tamilnadu. As the system tanks get supply from a permanent storage like reservoirs, dams etc. the area irrigated by this source is classified under canals. Canal irrigation accounted for 27.4% of the net area irrigated by all sources in the state. The net area irrigated by canals including system tanks during the year under review was 800161 ha as against 753819 ha recording an increase of 46342 ha i.e. 6.1%. The net area irrigated by canals is the highest in Thiruvarur district with 147564 ha (18.7%) followed by Thanjavur district with 134634 ha (17.4%) and Nagapattinam district with 125014 ha (15.7%) of the total net area irrigated by canals in the State.
Tanks (Non-System Tanks Only)
The non-system tanks which are fed partly from their independent catchment areas and partly from the diversion of river water and jungle streams depend fully on rain. The net area irrigated by non-system tanks is 575352 ha registering an increase of 109997 ha or 23.6% over previous year. The extent of area irrigated by tanks during the year is the highest in Sivagangai district with 12.7% followed by Pudukkottai district with 12.5%, Villupuram district with 10.6% and Kancheepuram district with 10.6%.
Wells
Wells are the principal source of irrigation in Tamilnadu. During the year under review, open wells and tube-wells continued to be the principal sources of irrigation. The net area irrigated by open wells and tube-wells together accounted for 1536808 ha (about 52.6 % of the total net area irrigated showing an increase of 136414 ha i.e. 9.7%. The net area irrigated by wells during the year was the highest in Villupuram district with 11.41% of the total net area irrigated by the wells in the state followed by 7.5% in Coimbatore district and 7.0% in Thiruvannamalai district.
Gross Area Irrigated
Gross area irrigated includes the net area irrigated and the area irrigated more than once. Gross area irrigated by all sources is 3396700 ha registering an increase of 309592 ha or 10.0% over the previous year due to better rainfall.
Irrigation Intensity
The irrigation intensity (The ratio of gross area irrigated to net area irrigated) is 1.16 for the state. The ratio is significantly high in the districts of Kanyakumari (1.40), Thiruvallur (1.40) Thiruvannamalai (1.36), Kancheepuram (1.27), Tirunelveli (1.26) and Nagapattinam (1.22)
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