Under the scheme over of land were brought under irrigation. The British also constructed a number of dams and canals for irrigation. An upper dam was constructed across the Kollidam river near Srirangam island. The Dowlaishwaram dam across the Godavari river, the Gunnavaram aqueduct across the Vaineteyam Godavari, the Kurnool-Cuddapah canal and the Krishna dam are examples of major irrigation works carried out by the British. In 1946–47, the total area under irrigation was acres which yielded a return of 6.94% on capital outlay. Trade, industry and commerce The trade of the Madras Presidency comprised that of both the Presidency with other Provinces and its overseas trade. External trade made up 93 percent of the total with internal trade making up the remainder. Foreign trade accounted for 70 percent of the total while 23 percent was inter-provincial. In 1900–01, imports from other provinces of British India amounted to 13.43 crores while exports to other provinces amounted to 11.52 crores. During the same year, exports to other countries reached 11.74 crores while imports were valued at 66.2 million. At the time of India's independence, imports of the Presidency amounted to 71.32 crores a year while exports were valued at 645.1 million. Trade with the United Kingdom made up 31.54% of the total trade of the Presidency with Madras the chief port accounting for 49% of the total trade. Cotton piece-goods, cotton twist and yarn, metals and kerosene oil were the main items of import while animal hides and skins, raw cotton, coffee and piece-goods were the chief exports. Raw cotton, animal hides, oil seeds, grains, pulses, coffee, tea and cotton manufactures were the main items of sea trade. Most of the sea trade was carried through the presidency's principal port of Madras. Other important ports were Gopalpur, Kalingapatnam, Bimlipatnam, Visakhapatnam, Masulipatnam, Cocanada, Madras, Cuddalore, Negapatam, Pamban and Tuticorin on the east coast along with Mangalore, Cannanore, Calicut, Cochin, Alleppey, Quilon (Coulão) and Colachel on the western seaboard. The port of Cochin was taken over by the Government of India on 1 August 1936, and that of Madras on 1 April 1937. There were Chambers of Commerce in Madras, Cochin and Cocanada. These chambers each nominated a member to the Madras Legislative Council. Cotton-ginning and weaving were two of the main industries in the Madras Presidency. Cotton was produced in large quantities in the Bellary district and was pressed in Georgetown, Madras.