The Nan River (, , ) is a river in Thailand. It is one of the most important tributaries of the Chao Phraya River.
Geography
The Nan River originates in the Luang Prabang Range, Nan Province. The provinces along the river after Nan Province are Uttaradit, Phitsanulok and Phichit. The Yom River joins the Nan River at Chum Saeng District, Nakhon Sawan Province. When the Nan river joins together with the Ping River at Pak Nam Pho within the town Nakhon Sawan it becomes the Chao Phraya River. The Nan river runs about south.
Tributaries
The chief tributary of the Nan is the Yom River, which joins the Nan within Chum Saeng District in Nakhon Sawan Province. Other direct tributaries include Khlong Butsabong and Khlong San Thao of the lower Nan Basin, the Wat Ta Yom and Wang Thong Rivers which join the Nan within Phichit Province, the Khwae Noi River which joins the Nan within Phitsanulok Province, Khlong Tron and Nam Pat, which join the Nan within Uttaradit Province, Lam Wa, Nam Haet, Nam Pua, Nam Yao and Nam Hao, which join the Nan within Nan Province.
Waterfalls
Kaeng Luang is a waterfall on the Nan River in Nan Province.
Drainage
Greater Nan Basin
The expanse of the Nan River's tributaries, i.e. the Nan River System, together with the land upon which falling rain drains into these bodies of water, form the Greater Nan Drainage Basin, which is part of the Chao Phraya watershed. The total area drained by the Nan and its tributaries is .
Much of the lower basin has perfect soil for farming.
Nan Basin
Most drainage analyses, however, divide the Greater Nan Basin into the Nan Basin and the Yom River Basin. Using this convention, and subtracting the of land drained by the Yom and its tributaries, the Nan basin drains a total of of land in the provinces of Phitsanulok, Phichit, Nan and Uttaradit.