River Systems of Thailand

The two principal river systems of Thailand are the Chao Phraya and the Mekong. Together, these rivers support the irrigation for Thailand's agricultural economy. In addition to these two large systems, there are a number of other river systems and individual rivers which drain the lands within Thailand's borders into the Gulf of Thailand and the Andaman Sea. The Mekong is the only river system in Thailand which drains into the South China Sea.

Chao Phraya River System

The Chao Phraya River System is the main river system of Thailand, as its basin defines much of the region of central Thailand. The Chao Phraya River begins at the confluence of the Ping and Nan river at Nakhon Sawan (also called Pak Nam Pho) in the Nakhon Sawan province. It then flows from north to south for 372 km from the central plains through Bangkok to the Gulf of Thailand. In Chainat, the river splits into the main river course and the Tha Chin river, which then flows parallel to the main river and exits to Gulf of Thailand at about 35 km west of Bangkok in Samut Sakhon. In the low alluvial plain which begins below the Chainat dam, many small canals ("khlong") split off from the main river. The khlong are used for the irrigation of the region's rice paddies.

Tributaries

The principal tributaries of the Chao Phraya River are the Pa Sak River, the Sakae Krang River, the Nan River (along with its principal confluent the Yom River), the Ping River (with its principal confluent the Wang River), and the Tha Chin River.. [http://157.82.150.160/GAME-T/GAIN-T/routine/rid-river/RIDstations.html Royal Irrigation Department River Gauges Report] ] Each of these tributaries (and the Chao Phraya itself) is further tributed by additional minor tributaries often referred to as "khwae". All of the tributaries, including the lesser khwae, form an extensive tree-like pattern, with branches flowing through nearly every province in central and northern Thailand. [http://157.82.150.160/GAME-T/GAIN-T/routine/rid-river/RIDstations.html Royal Irrigation Department River Gauges Report] ] None of the tributaries of the Chao Phraya extend beyond the nation's borders.Google Earth] The Nan and the Yom River flow nearly parallel from Phitsanulok to Chumsaeng in the north of Nakhon Sawan province. The Wang River enters the Ping River near Sam Ngao district in Tak province.

Drainage

The expanse of the Chao Phraya River and its tributaries, i.e. the "Chao Phraya river system", together with the land upon which falling rain drains into these bodies of water, form the "Chao Phraya watershed." [http://www.premcenter.org/index.php?option=com_content&task=view&id=246&Itemid=830 River and Watershed Facts on the Chao Phraya] ] The Chao Phraya watershed is the largest watershed in Thailand, covering approximately 35% of the nation's land, and draining an area of 157,924 km². [http://www.pwa.co.th/english/l_basins.htm Basins of Thailand] ]

Lesser Gulf River Systems

There are numerous rivers which flow into the Gulf of Thailand, including a number of west coast gulf rivers, east coast gulf rivers, and rivers which drain into the gulf on the east coast of the Malay Peninsula. The following river systems, in addition to the Chao Phraya, are the most significant gulf systems in Thailand:

Bang Pa Kong

The Bang Pa Kong River is a river in eastern Thailand. The river originates at the confluence of the Nakhon Nayok River and the Prachinburi River at Pak Nam Yotaka in Amphoe Ban Sang, Prachinburi Province. It empties into the Gulf of Thailand in the northeastern tip of the Bay of Bangkok. The Bang Pa Kong's principal tributaries are the Nakhon Nayok River and the Prachin Buri River. The watershed of the Bang Pa Kong is about 17,000 km².

Phetchaburi

The Phetchaburi River is a river in western Thailand. It originates in Kaeng Krachan National Park, Kaeng Krachan district and flows through Tha Yang, Ban Lat, Mueang Phetchaburi and mouths into the Bay of Bangkok in Ban Laem district. It is 210 km long, most of which is within the Phetchaburi Province. It is the backbone of this province.

Mae Klong

The Mae Klong River is a river in western Thailand. The river begins at the confluence of the Khwae Noi or Kwai Sai Yoke and the Khwae Yai River or Kwai Si Sawasdi in Kanchanaburi, pass Ratchaburi Province and empties into the Gulf of Thailand in Samut Songkhram.

Pran Buri

The Pran Buri River is a river in the Prachuap Khiri Khan Province, Thailand, on the Kra Isthmus of the Malay Peninsula. The Pran Buri river originates in southern part of the Kaeng Krachan National Park, and after 130 km mouths into the Gulf of Thailand. The only town at the river course is Pranburi, the center of the Pran Buri district. The watershed of the Pran Buri River has an area of about 2000 km².

Khlong Kui

The Khlong Kui River drains into the Gulf of Thailand from the Malay Peninsula in Thailand. It flows through Ban Pong Kasang and Ban Thung Faek, Kui Buri district, Prachuap Khiri Khan Province. [http://157.82.150.160/GAME-T/GAIN-T/routine/rid-river/RIDstations.html Royal Irrigation Department River Gauges Report] ]

Tapi and Phum Duang

The Tapi River with its main tributary Phum Duang drain the area of Surat Thani Province. The total watershed of the river system is about 11,500 km².

Pattani

The Pattani River is the longest of all Thai rivers on the Malay Peninsula with a total length of 214 km.

Mekong River System

The Mekong River, one of the world’s major rivers, drains into the South China Sea. It is the 11th-longest river in the world, and the 12th-largest by volume (discharging 475 km³ of water annually). Its estimated length is 4880 km, and it drains an area of 810,000 km². [ [http://www.shangri-la-river-expeditions.com/1stdes/mekong/mekongsource/IGSNRR2001.html Source of the Mekong River (Langcang Jiang) ] ] From the Tibetan Plateau it runs through China's Yunnan province, Myanmar, Thailand, Laos, Cambodia and Vietnam. All except China and Myanmar belong to the Mekong River Commission. The extreme seasonal variations in flow and the presence of rapids and waterfalls have made navigation extremely difficult. Approximately half the river's length is in China, where it is known as the "Meigong" in Chinese (zh-cp|c=湄公河|p=Méigōng Hé). The river next forms the border between Myanmar and Laos for 200 km, at the end of which it meets the tributary Ruak River at the Golden Triangle. This point also marks the division between the "Upper" and "Lower Mekong". The river then divides Laos and Thailand, before a stretch passing through Laos alone. It is known as "Maè Nam Khong" (Mother of all rivers) in both Lao and Thai (แม่น้ำโขง). The river again marks the Lao-Thai border in the stretch which passes Vientiane, followed by a short stretch through Laos alone. In Cambodia, the river is called the "Mékôngk" or "Tonle Thom" (great river). Just above Phnom Penh is the confluence with the Tonle Sap, the main Cambodian tributary. Below Phnom Penh, it divides into the Bassac and the Mekong proper, which both flow into the Mekong Delta in Vietnam. In Vietnamese, the river as a whole is known as "Mê Kông". In Vietnam, the river divides into two major branches, the " Tiền Giang" (Front River) and "Hậu Giang" (Back River). These in turn enter the South China Sea through nine estuaries.

Thai Tributaries

The following are the principal tributaries of Mekong River which flow through Thailand (tributaries entirely outside the Thai border not shown).
*Ing River (joins the Mekong in Thailand)
*Ruak River (joins the Mekong in Thailand)
*Mun River (joins the Mekong in Thailand)
**Chi River (joins the Mun in Thailand)
**Dom Noi River (joins the Mun in Thailand)
*Kok River (joins the Mekong in Thailand)
*Lam Ta Klong River (forms part of the border between Laos and Thailand)
*Tonlé Sap River (joins the Mekong in Cambodia, but extends into Thailand)

Drainage

The Mekong drains a considerable portion of northeast Thailand. In terms of Thai land area drained, it is second only to the Chao Phraya system.

alawin River System

The Salawin River rises in Tibet (Tibetan རྒྱ་མོ་དངུལ་ཆུ་) after which it flows through Yunnan, where it is known as the "Nujiang" river (zh-cp|c=怒江|p=Nù Jiāng), although either name can be used for the whole river. The river is 2815 km long. It then leaves China and meanders through Myanmar (where it is known as the "Thanlwin") and Thailand (where it is known as the "Salawin", Thai: สาละวิน) on its way to emptying in the Andaman Sea by Mawlamyaing (Moulmien).

Thai Tributaries

The principal tributaries of the Salawin which flow through Thailand are the Moei River and the Pai River.

Other Andaman Sea Rivers

In addition to the Salween River, there are a number of rivers which drain into the Andaman Sea from the west coast of the Malay Peninsula. None of them are significantly extensive, however, to be considered "river systems".

References