Which river does the Mettur Dam regulate?

Major rivers of India: Ganga (2525 km, longest in India), Godavari (1465 km, longest peninsular river), Krishna (1400 km), Yamuna (1376 km), Narmada (1312 km), Indus (1114 km in India). Rivers are classified as Himalayan rivers (perennial, fed by glaciers) and Peninsular rivers (mostly seasonal). The Ganga basin is the largest river basin in India.

Important lakes of India: Wular Lake (largest freshwater lake, Jammu and Kashmir), Dal Lake (J&K), Chilika Lake (largest brackish water lake, Odisha, Ramsar site), Vembanad Lake (longest lake, Kerala), Sambhar Lake (largest saltwater lake, Rajasthan), Loktak Lake (largest freshwater lake in northeast, Manipur), Pushkar Lake (Rajasthan).

The Ganga River originates from Gangotri Glacier in Uttarakhand and flows eastward through UP, Bihar, West Bengal before emptying into the Bay of Bengal via the Sundarbans delta. Major tributaries: Yamuna (joins at Prayagraj), Ghaghara, Son, Gandak, and Kosi. Prayagraj Sangam is the meeting of Ganga, Yamuna, and Saraswati. Ganga is India's national river.

Important South Indian rivers: Godavari (Indravati tributary - longest peninsular river), Krishna (Bhima, Tungabhadra tributaries), Kaveri (source of dispute between Karnataka and Tamil Nadu), Mahanadi (forms Odisha delta), Narmada (flows west into Arabian Sea - sacred river), Tapti/Tapi (also flows west into Arabian Sea).

World's largest freshwater lakes: Lake Superior (largest by area, Canada-USA), Lake Baikal (deepest, Russia), Lake Victoria (Africa). Caspian Sea is actually saltwater - largest lake by area. In India: Wular Lake (J&K) is largest freshwater lake. Chilika Lake (Odisha) is largest brackish water lake and important Ramsar wetland site. These are common GK questions in competitive exams.