The Yom River (, , ; , ) is a river in Thailand. It is the main tributary of the Nan River (which itself is a tributary of the Chao Phraya River). The Yom River has its source in the Phi Pan Nam Range in Pong District, Phayao Province. Leaving Phayao, it flows through the Phrae and Sukhothai provinces as the main water resource of both provinces before it joins the Nan River at Chum Saeng District, Nakhon Sawan Province.
Tributaries Tributaries of the Yom include the Nam Mae Phong (), Ngao River, Nam Ngim, Huai Mae Sin, Nam Suat (), Nam Pi, Mae Mok, Huai Mae Phuak, Mae Ramphan, Nam Mae Lai, Nam Khuan, and Nam Mae Kham Mi.
Yom Basin The Yom river and its tributaries drain a total area of of land (called the Yom Basin) in the provinces of Sukhothai, Phitsanulok, Phichit, Phrae, and Lampang.Basins of Thailand The Yom Basin is part of the Greater Nan Basin and the Chao Phraya Watershed.
A controversial large dam was planned on the Yom River in the central area of the Phi Pan Nam mountains in Kaeng Suea Ten in 1991 but the project was later abandoned. The debate about the dam was opened again in 2011.Bangkok Post Floodgates reopen in dam debate Currently a proposal is being debated to build two smaller dams on the Yom River in the area instead of the Kaeng Suea Ten mega-dam.Bangkok Post - Study to decide Yom River fate History Near old Si Satchanalai the Yom once flowed round the western end of a ridge of bedrock hills. In a 1994 study Paul Bishop and colleagues found those channels abandoned about 1,700 years ago, on uncalibrated radiocarbon dates, when the river began to flow through the ridge. River gravels from the new course underlie the first settlement on the river bend just downstream, dated to 1259 ± 28 radiocarbon years BP, which is therefore a minimum age for the change.
The river banks between modern Si Satchanalai and Sawankhalok carried the Sangkhalok industry. Chusak Satienpattanodom describes a kiln field running along both banks at Ban Ko Noi and Ban Pa Yang, the oldest kilns dug into the high banks where fuel could be brought by boat.
The upper basin carried a metal industry as well. In the hills at the head of the Mae Ramphan, a tributary that joins the Yom at Sukhothai, survey has recorded ancient mines and more than a hundred iron-smelting furnaces. Excavation at one of them dates smelting between 1128 and 1280.
The older town centre of Chaliang stands inside a loop of the river, with water on three sides. A change in the river's course that cut the bank is one of three reasons he gives for the founding of the walled city about 2 km upstream. Michael Vickery also held that the river had shifted its course a good deal, and took old wells exposed in the bank as proof that it once ran some distance away. Bishop and colleagues held that the Yom has had roughly its present course past the site since the first settlement, and found the tradition of a change of course after the city's founding difficult to sustain. The walled city stands at a rapid also called Kaeng Luang, which is not the rapid of the same name in Phayao province. Fishing there is attested by net weights recovered in excavation, both glazed and unglazed. The rapid was later blasted by the Bombay Burmah Trading Corporation to clear the passage for floated teak.
On the gauge records at Kaeng Luang for 1952–1989, a flood with a return period of 10 to 20 years can overtop the bank at the old city. The highest flood of that record, on 8 September 1980, only reached the top of the bank. At high water the river also runs through four channels on the inside of the meander below the rapid, which Bishop and colleagues read as flood chutes rather than former courses.
Protected areas The Yom River flows through Mae Yom National Park in Phrae Province.
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References
External links
Living River Siam Bangkok Post - Living in the ugly shadow of the kaeng sua ten dam