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The Chao Phraya ( or ) ( th, แม่น้ำเจ้าพระยา , or ) is the major river in Thailand, with its low alluvial plain forming the centre of the country. It flows through
Bangkok Bangkok is the capital and most populous city of Thailand Thailand ( th, ประเทศไทย), historically known as Siam, () officially the Kingdom of Thailand, is a country in Southeast Asia Southeast Asia or Southeastern ...

Bangkok
and then into the
Gulf of Thailand The Gulf of Thailand, also known as the Gulf of Siam, is a shallow inlet in the southwestern South China Sea The South China Sea is a of the . It is bounded in the north by the shores of (hence the name), in the west by the , in the east ...

Gulf of Thailand
.


Etymology

On many old European maps, the river is named the ''Menam'' or ''Mae Nam'' (Thai: แม่น้ำ), which is simply the Thai word for "river". James McCarthy, F.R.G.S., who served as Director-General of the Siamese Government Surveys prior to establishment of the Royal Survey Department, wrote in his account, "''Mae Nam'' is a generic term, ''mae'' signifying "mother" and ''Nam'' "water," and the epithet Chao P'ia signifies that it is the chief river in the kingdom of Siam." H. Warington Smyth, who served as Director of the Department of Mines in Siam from 1891 to 1896, refers to it in his book first published in 1898 as "the Mae Nam Chao Phraya". In the English-language media in Thailand, the name Chao Phraya River is often translated as ''river of kings''.


Geography

The Chao Phraya begins at the
confluence In geography Geography (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ...

confluence
of the and
Nan In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes and development of both computer hardware , hardware and softw ...
rivers at
Nakhon Sawan Nakhon Sawan ( th, นครสวรรค์, ) is a city (''thesaban nakhon Thesaban ( th, เทศบาล, , ) are the municipalities of Thailand ) , royal_anthem = '' Sansoen Phra Barami''( en, "Glorify His prestige") , ...
(also called Pak Nam Pho) in
Nakhon Sawan Province Nakhon Sawan ( th, นครสวรรค์, ) is one of Thailand's seventy-six provinces (''changwat'') lies in lower northern Thailand. Neighbouring provinces are (from north clockwise) Kamphaeng Phet, Phichit, Phetchabun, Lopburi, Sin ...
. After this it flows south for from the central plains to
Bangkok Bangkok is the capital and most populous city of Thailand Thailand ( th, ประเทศไทย), historically known as Siam, () officially the Kingdom of Thailand, is a country in Southeast Asia Southeast Asia or Southeastern ...

Bangkok
and the
Gulf of Thailand The Gulf of Thailand, also known as the Gulf of Siam, is a shallow inlet in the southwestern South China Sea The South China Sea is a of the . It is bounded in the north by the shores of (hence the name), in the west by the , in the east ...

Gulf of Thailand
. In
Chai Nat Chai Nat ( th, ชัยนาท, ) is a town (''thesaban mueang'') in central Thailand, capital of Chai Nat Province. It covers the whole ''tambon'' tambon Nai Mueang and parts of Ban Kluai, Tha Chai and Khao Tha Phra, all in Amphoe Mueang Ch ...
, the river then splits into the main course and the
Tha Chin The Tha Chin river ( th, แม่น้ำท่าจีน, , ) is a distributary of the Chao Phraya River, Chao Phraya river, Thailand. It splits near the Chai Nat Province, province of Chai Nat and then flows west from the Chao Phraya thro ...
River, which then flows parallel to the main river and exits in the Gulf of Thailand about west of Bangkok in
Samut Sakhon Samut Sakhon ( th, สมุทรสาคร, Pronunciation is a City in Thailand, capital of Samut Sakhon Province. It is a stop on the Maeklong Railway. Samut Sakhon is 48 km from Bangkok. It is part of the Bangkok Metropolitan Region. ...
. In the low alluvial plain which begins below the
Chainat Dam The Chao Phraya Dam ( th, เขื่อนเจ้าพระยา, , ) is a barrage dam in Sapphaya District, Chai Nat Province, Thailand. It regulates the flow of the Chao Phraya River as it passes into lower central Thailand, distributing ...
, there are many small canals (''
khlong A khlong (also commonly spelled ''klong''; th, คลอง, ) commonly refers to a canal Canals are waterways channels Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a l ...
'') which split off from the main river. The ''khlongs'' are used for the irrigation of the region's rice paddies. The rough coordinates of the river are 13 N, 100 E. This area has a wet monsoon climate, with over of rainfall per year. Temperatures range from in Bangkok.


River engineering

The lower Chao Phraya underwent several man-made modifications during the Ayutthaya period. Several shortcut canals were constructed to bypass large loops in the river, shortening the trip from the capital city to the sea. The course of the river has since changed to follow many of these canals. * In 1538, Thailand's first
river engineering River engineering is a discipline of civil engineering Civil engineering is a professional engineering Regulation and licensure in engineering is established by various jurisdictions of the world to encourage public welfare, safety, well- ...
of a long canal was dug at the order of King Chairachathirat. It was called "Khlong Lat", and today forms a part of
Khlong Bangkok Noi file:Khlongbangkoknoi050624b.jpg, 250px, Khlong Bangkok Noi near Wat Sri Sudaram Khlong Bangkok Noi ( th, คลองบางกอกน้อย; lit 'Bangkok Noi Canal') is a ''khlong'' (คลอง; canal) in Bangkok; its name is the origin ...
. It shortened the route by 13–14 km for ships from the Gulf of Siam to the then-capital city, Ayutthaya.Steve Van Beek: ''The Chao Phya'', p.39 * In 1542, a two kilometer-long canal, "Khlong Lat Bangkok", was completed. The Chao Phraya then diverted along the new canal, its old course becoming part of Khlong Bangkok Noi and
Khlong Bangkok Yai Khlong Bangkok Yai ( th, คลองบางกอกใหญ่; lit: Bangkok Yai Canal) is a historic ''khlong'' (คลอง; canal) of Bangkok. Originally it was part of the Chao Phraya River. In the past, the course of the Chao Phraya was ...
. It is said to have shortened the river route by . * In 1608, a seven kilometer-long "Khlong Bang Phrao" canal was completed and has shortened the Chao Phraya's original route by . * In 1636, the "Khlong Lat Mueang Nonthaburi" was completed. * In 1722, the two kilometre long "Khlong Lat Kret Noi" shortened the Chao Phraya by . This route formed the island of
Ko Kret Ko Kret ( th, เกาะเกร็ด, ) is a small island in the Chao Phraya River The Chao Phraya ( or ) ( th, wikt:เจ้าพระยา, แม่น้ำเจ้าพระยา , or ) is the major river in Thailand, wit ...
.


River settlements

Cities along the Chao Phraya include, from north to south,
Nakhon Sawan Province Nakhon Sawan ( th, นครสวรรค์, ) is one of Thailand's seventy-six provinces (''changwat'') lies in lower northern Thailand. Neighbouring provinces are (from north clockwise) Kamphaeng Phet, Phichit, Phetchabun, Lopburi, Sin ...
,
Uthai Thani Province Uthai Thani ( th, อุทัยธานี, ), one of Thailand's seventy-six provinces (''changwat'') lies in lower northern Thailand. Neighboring provinces are (from north clockwise) Nakhon Sawan, Chai Nat, Suphan Buri, Kanchanaburi and ...
,
Chai Nat Province Chai Nat ( th, ชัยนาท, ) is one of the central Provinces of Thailand, provinces (''changwat'') of Thailand. Neighbouring provinces are (from north clockwise) Nakhon Sawan province, Nakhon Sawan, Sing Buri province, Sing Buri, Suphanbur ...
,
Sing Buri Province Sing Buri ( th, สิงห์บุรี, ) is one of the central Provinces of Thailand, provinces (''changwat'') of Thailand. Neighboring provinces are (from north clockwise) Nakhon Sawan Province, Nakhon Sawan, Lopburi Province, Lopburi, Ang ...
,
Ang Thong Province Ang Thong ( th, อ่างทอง, ) is one of the central Central is an adjective usually referring to being in the center (disambiguation), center of some place or (mathematical) object. Central may also refer to: Directions and general ...
,
Ayutthaya Province Phra Nakhon Si Ayutthaya (or Ayutthaya, th, พระนครศรีอยุธยา, ) is one of the central provinces A province is almost always an administrative division Administrative division, administrative unitArticle 3(1). , c ...
,
Pathum Thani Province Pathum Thani ( th, ปทุมธานี, ) is one of the central Provinces of Thailand, provinces (''changwat'') of Thailand. Neighboring provinces are (from north clockwise): Ayutthaya Province, Ayutthaya, Saraburi Province, Saraburi, Nakhon ...
,
Nonthaburi Province Nonthaburi ( th, นนทบุรี, ) is one of the central provinces (''changwat'') of Thailand ) , royal_anthem = '' Sansoen Phra Barami''( en, "Glorify His prestige") , image_map = , map_caption = , capita ...
,
Bangkok Bangkok is the capital and most populous city of Thailand Thailand ( th, ประเทศไทย), historically known as Siam, () officially the Kingdom of Thailand, is a country in Southeast Asia Southeast Asia or Southeastern ...

Bangkok
, and
Samut Prakan Province#REDIRECT Samut Prakan province {{Redirect category shell, 1= {{R from other capitalisation {{R from move ...
. These cities are among the most historically significant and densely populated settlements of Thailand due to their access to the waterway.


Transportation

Major bridges cross the Chao Phraya in Bangkok: the
Rama VI Vajiravudh ( th, วชิราวุธ, , 1 January 188126 November 1925), was the sixth Monarchy of Thailand, monarch of Rattanakosin Kingdom, Siam (Rama VI) under the Chakri dynasty, ruling from 1910 until his death in 1925. King Vajiravud ...
railroad bridge; Phra Pin-klao near the
Grand Palace The Grand Palace ( th, พระบรมมหาราชวัง, Royal Institute of Thailand The Royal Society of Thailand ( th, ราชบัณฑิตยสภา, , ), formerly known as the Royal Society of Siam, is the national ...

Grand Palace
;
Rama VIII Ananda Mahidol ( th, พระบาทสมเด็จพระปรเมนทรมหาอานันทมหิดล; ; 20 September 1925 – 9 June 1946), posthumous reigning title Phra Athamaramathibodin, was the eighth Monarch ...

Rama VIII
, a single tower asymmetrical cable-stayed bridge;
Rama IX Bhumibol Adulyadej ( th, ภูมิพลอดุลยเดช; ; ; 5 December 192713 October 2016), conferred with the title King Bhumibol the Great in 1987 (officially conferred by King Vajiralongkorn in 2019), was the ninth Monarchy of ...

Rama IX
, a semi-symmetric cable-stayed bridge; and
Mega Bridge The Bhumibol Bridge ( th, สะพานภูมิพล), also known as the Industrial Ring Road Bridge ( th, สะพานวงแหวนอุตสาหกรรม) is part of the 13 km long Industrial Ring Road connecting sout ...
, on the Industrial Ring Road. In Bangkok, the Chao Phraya is a major transportation artery for a network of river buses, cross-river ferries, and water taxis ("longtails"). More than 15 boat lines operate on the rivers and canals of the city, including .


Tributaries

The principal tributaries of the Chao Phraya River are the
Pa Sak River The Pa Sak River ( th, แม่น้ำป่าสัก, , Pronunciation is a river in central Thailand. The river originates in the Phetchabun Mountains, Dan Sai District, Loei Province, and passes through Phetchabun Province as the backbon ...
, the
Sakae Krang River The Sakae Krang River ( th, แม่น้ำสะแกกรัง, , ) is a tributary of the Chao Phraya River. It originates in Mae Wong National Park, Nakhon Sawan Province. It is long, with most of its length in Uthai Thani Province. It j ...
, the
Nan River The Nan River ( th, แม่น้ำน่าน, , ) is a river in Thailand Thailand ( th, ประเทศไทย), historically known as Siam, () officially the Kingdom of Thailand, is a country in Southeast Asia. It is located ...
(along with its principal confluent the
Yom River The Yom River ( th, แม่น้ำยม, , ) is a river in Thailand Thailand ( th, ประเทศไทย), historically known as Siam, () officially the Kingdom of Thailand, is a country in Southeast Asia. It is located at the c ...
), the
Ping River The Ping River ( th, แม่น้ำปิง, , ), along with the Nan River, is one of the two main tributaries of the Chao Phraya River. It originates at Doi Thuai in the Daen Lao Range, in Amphoe Chiang Dao, Chiang Dao district, Chiang Mai P ...

Ping River
(with its principal confluent, the
Wang River The Wang River ( th, แม่น้ำวัง, , ) is a river in northern Thailand Northern Thailand ) , royal_anthem = '' Sansoen Phra Barami''( en, "Glorify His prestige") , image_map = , map_caption = , c ...
), and the
Tha Chin River The Tha Chin river ( th, แม่น้ำท่าจีน, , ) is a distributary of the Chao Phraya River, Chao Phraya river, Thailand. It splits near the Chai Nat Province, province of Chai Nat and then flows west from the Chao Phraya thro ...
. Each of these tributaries (and the Chao Phraya itself) is augmented by minor tributaries 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 Thailand ( th, ประเทศไทย), historically known as Siam, () officially the Kingdom of Thailand, is a country in Southeast Asia. It is located at the centre of the Mainland Southeast Asia, Indochinese Peninsula, spanning , wi ...

Thailand
. 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 Phitsanulok ( th, พิษณุโลก, ) is an important, historic city in lower northern Thailand and is the capital of Phitsanulok Province Phitsanulok Province ( th, พิษณุโลก, ), one of Thailand's seventy-six provinces ...

Phitsanulok
to Chumsaeng in the north of Nakhon Sawan Province. The
Wang River The Wang River ( th, แม่น้ำวัง, , ) is a river in northern Thailand Northern Thailand ) , royal_anthem = '' Sansoen Phra Barami''( en, "Glorify His prestige") , image_map = , map_caption = , c ...
enters the Ping River near Sam Ngao district in
Tak Province Tak ( th, ตาก, ) is one of Thailand's seventy-six Provinces of Thailand, provinces (''changwat'') lies in Northern Thailand#Regional classification of northern Thailand, lower northern Thailand. Neighbouring provinces are (from north clockwis ...
.


Length

When measured from the most commonly accepted source which the confluence of the Ping and Nan River in Nakhon Sawan, it measures . However, when measured from the longest source which is the origin point of the Nan River in the
Luang Prabang Range The Luang Prabang Range ( th, ทิวเขาหลวงพระบาง, ), named after Luang Prabang Luang Phabang, (Lao language, Lao: wikt:ຫລວງພະບາງ, ຫລວງພະບາງ/wikt:ຫຼວງພະບາງ, ...
, it measures .


Chao Phraya watershed

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 Watershed is a hydrological term, which has been adopted in other fields in a more or less figurative sense. It may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins ** European watershed * Drainage basin ...

watershed
.River and Watershed Facts on the Chao Phraya
The Chao Phraya watershed is the largest watershed in Thailand, covering approximately 35 percent of the nation's land, and draining an area of .
/ref> The watershed is divided into the following basins: * Pa Sak Basin * Sakae Krang Basin * Greater Nan Basin (composed of the Nan Basin and the Yom Basin, and usually divided as such in drainage analyses) * (composed of the and the Wang Basin, and usually divided as such in drainage analyses) * Tha Chin Basin (the basin of the Chao Phraya's most significant distributaries) *Finally the Chao Phraya Basin itself is defined as the portion of the Chao Phraya watershed drained by the Chao Phraya River itself, and not by its major tributaries or distributaries. As such, the Chao Phraya Basin drains of land. To the west, the central plain of Thailand is drained by the
Mae Klong The Mae Klong (, , ), sometimes spelled Mae Khlong or Meklong, is a river in western Thailand. The river begins at the confluence of the Khwae Noi River, Khwae Noi (Khwae Sai Yok) and the Khwae Yai River (Khwae Si Sawat) in Kanchanaburi Province ...
and the east by the
Bang Pakong River The Bang Pakong ( th, แม่น้ำบางปะกง, , ) is a river in east Thailand. The river originates at the confluence of the Phra Prong River and the Hanuman River near Kabin Buri District, Kabin Buri, Prachinburi Province. It e ...
. They are not part of the Chao Praya system. The landscape of the river basins is a very wide, flat, well-watered plain continuously refreshed with soil and sediment brought down by the rivers. The lower central plain from the delta north to
Ang Thong Province Ang Thong ( th, อ่างทอง, ) is one of the central Central is an adjective usually referring to being in the center (disambiguation), center of some place or (mathematical) object. Central may also refer to: Directions and general ...
is a flat, low area with an average of two metres above sea level. Further north and into the plains of the Ping and the Nan the elevation is over 20 m. Then the mountains that are the natural boundary of the Chao Praya watershed form a divide, which has, to some degree, historically isolated Thailand from other Southeast Asian civilisations. In northern Thailand the divide roughly corresponds to a long section of the political border of the country today. Southern portions of the divide's boundary correspond less to the nation's political border, because isolation in this area was prevented by the ease of transportation along the lowlands surrounding the Gulf of Thailand, allowing a unified Thai civilisation to extend beyond the watershed without issue. The slightly higher northern plains have been farmed for centuries and saw a major change from the 13th century during the
Sukhothai Kingdom The Sukhothai Kingdom ( th, สุโขทัย, , IAST: , ) was a post-classical Thai kingdom (Mandala (political model), mandala) in Mainland Southeast Asia surrounding the ancient capital city of Sukhothai Historical Park, Sukhothai in pr ...
in the 13th and 14th centuries and the Ayutthaya Kingdom that succeeded it when rice growing intensified with the introduction of
floating rice Deepwater rice are varieties of rice (''Oryza sativa'') grown in flooded conditions with water more than deep for at least a month.Catling, p. 2. More than people in Southeast Asia including Northeastern India rely on deepwater rice for their sus ...

floating rice
, a much faster-growing strain of rice from
Bengal Bengal (; bn, বাংলা/বঙ্গ, translit=Bānglā/Bôngô, ) is a geopolitical, cultural and historical region located in South Asia, specifically in the eastern part of the Indian subcontinent at the apex of the Bay of Bengal, p ...

Bengal
. The southern swamps meanwhile changed radically from the 18th century when King
Buddha Yodfa Chulaloke Phra Phutthayotfa Chulalok Maharaj (, 20 March 1737 – 7 September 1809), personal name Thongduang (), also known as Rama I, was the founder of the Rattanakosin Kingdom and the first Monarchy of Thailand, monarch of the reigning Chakri dyna ...
moved the capital of Siam to Bangkok, and a process of canalisation and cultivation began, especially as Thailand began to export rice from 1855.


Delta

The
Tha Chin River The Tha Chin river ( th, แม่น้ำท่าจีน, , ) is a distributary of the Chao Phraya River, Chao Phraya river, Thailand. It splits near the Chai Nat Province, province of Chai Nat and then flows west from the Chao Phraya thro ...
is the major distributary of the Chao Phraya River. The expanse of the Chao Phraya and
Tha Chin The Tha Chin river ( th, แม่น้ำท่าจีน, , ) is a distributary of the Chao Phraya River, Chao Phraya river, Thailand. It splits near the Chai Nat Province, province of Chai Nat and then flows west from the Chao Phraya thro ...
Rivers and their distributaries, starting at the point at which the distributaries diverge, together with the land amid the triangle formed by the outermost and innermost distributary, form the Chao Phraya
delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, a landform at the mouth of a river * D (NATO phonetic alphabet: "Delta"), the fourth letter of the modern English alphabet * Delta Air Lines, an Ame ...

delta
. The many distributaries of the Chao Phraya delta are interconnected by canals that serve both for irrigation and for transportation.


Ecology

The lowland areas of the Chao Phraya watershed in central Thailand have been designated as the Chao Phraya freshwater swamp forests, a
tropical and subtropical moist broadleaf forests Tropical and subtropical moist broadleaf forests (TSMF), also known as tropical moist forest, is a tropical The tropics are the region of Earth surrounding the Equator. They are delimited in latitude by the Tropic of Cancer in the North ...
ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including h ...
, an area about north to south and wide. The original swamp forests have almost entirely been removed as the plain has been converted to rice paddies, other agriculture, and urban areas like Bangkok. Much of the wildlife that once inhabited these plains has disappeared, including a large number of fish in the river systems, birds such as vultures, the
Oriental darter The Oriental darter (''Anhinga melanogaster'') is a water bird of tropical South Asia and Southeast Asia. It has a long and slender neck with a straight, pointed bill and, like the cormorant, it hunts for fish while its body is submerged in wate ...

Oriental darter
(''Anhinga melanogaster''),
white-eyed river martin The white-eyed river martin (''Pseudochelidon sirintarae'') is a passerine bird, one of only two members of the river martin subfamily of the swallows. Since it has significant differences from its closest relative, the African river martin, it ...
(''Pseudochelidon sirintarae''), the
sarus crane The sarus crane (''Antigone antigone'') is a large bird migration, nonmigratory Crane (bird), crane found in parts of the Indian subcontinent, Southeast Asia, and Australia. The tallest of the flying birds, standing at a height of up to , they ...

sarus crane
(''Grus antigone'') and animals such as
tiger The tiger (''Panthera tigris'') is the largest extant taxon, living Felidae, cat species and a member of the genus ''Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, i ...

tiger
s, s,
Javan rhinoceros The Javan rhinoceros (''Rhinoceros sondaicus''), also known as the Sunda rhinoceros or lesser one-horned rhinoceros, is a very rare member of the family Rhinocerotidae A rhinoceros (, , ), commonly abbreviated to rhino, is a member of a ...
es, and the much-hunted
Schomburgk's deer The Schomburgk's deer (''Rucervus schomburgki'') is an extinct species of deer once endemic Endemism is the state of a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank o ...
. Today we can only guess at the original habitat and wildlife by comparing it with neighbouring countries. It is believed that the area would have consisted of freshwater swamps inland and salty
mangrove A mangrove is a shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Pl ...

mangrove
s on the coast and the river estuaries. The swamp would have been covered in ''
Phragmites ''Phragmites'' () is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), ...
'' marsh grasses. Today there is a small area of this remaining in
Khao Sam Roi Yot National Park Khao Sam Roi Yot National Park ( th, อุทยานแห่งชาติเขาสามร้อยยอด, ) is a marine national park in Kui Buri District Image:Kui Buri Railway Station Thailand.JPG, 250px, Kui Buri railway stat ...

Khao Sam Roi Yot National Park
, a relic of the original landscape. As so much has been cleared or altered the potential for creating large protected areas to preserve original habitat no longer exists. However much wildlife does remain in the rice fields and steps may be taken to preserve these as urban and industrial development on the plains is ongoing and the
Industrial Estate Authority of Thailand The Industrial Estate Authority of Thailand (I-EA-T), ( th, การนิคมอุตสาหกรรมแห่งประเทศไทย) is a state enterprise under control of the Ministry of Industry (Thailand), Ministry of Industry ...
has very little control or planning over this. Particular threats come from the conversion of rice paddies to large-scale production of prawns by pumping in seawater, and the use of pesticides to eliminate the introduced snail,''
Pomacea canaliculata ''Pomacea canaliculata'', common name, commonly known as the golden apple snail or the channeled apple snail, is a species of large freshwater snail with gills and an operculum (gastropod), operculum, an Aquatic animal, aquatic gastropod mollusc ...
'', which damages rice plants. There are populations of threatened birds, including colonies of breeding water birds such as the world's largest populations of the near-threatened
Asian openbill The Asian openbill or Asian openbill stork (''Anastomus oscitans'') is a large wading bird in the stork family Ciconiidae. This distinctive stork is found mainly in the Indian subcontinent and Southeast Asia. It is greyish or white with glossy bl ...

Asian openbill
(''Anastomus oscitans''), and other birds such as the wintering
black kite The black kite (''Milvus migrans'') is a medium-sized bird of prey Birds of prey, also known as raptors, include species of bird Birds are a group of s constituting the Aves , characterised by s, toothless beaked jaws, the of e ...

black kite
(''Milvus migrans''). Endemic mammals that remain are the limestone rat (''Niviventer hinpoon''), Neill's long-tailed giant rat (''Leopoldamys neilli''), and the near-endemic
Thailand roundleaf bat The Thailand roundleaf bat (''Hipposideros halophyllus'') is a species of bat in the family Hipposideridae. It is endemic to Thailand. Distribution ''Hipposideros halophyllus'' is found in: *Khao Samor Khon, Lopburi Province (1,000-1,400 individ ...
(''Hipposideros halophyllus''). The Chao Phraya basin is home to about half a dozen endemic
dragonflies A dragonfly is a flying insect The Pterygota (Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referr ...

dragonflies
and
damselflies Damselflies are flying insect The Pterygota (Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred ...
. The conservation status of most of these in unclear (they are rated as
data deficient A data deficient (DD) species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of or ...
by the
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization An international organization (also known as an international institut ...
), but '' Cryptophaea saukra'' is critically endangered and ''Caliphaea angka'' is Endangered species, endangered.Allen, D.J.; Smith, K.G. & Darwall, W.R.T. (editors)(2008).
The status and distribution of freshwater fishes of Indo-Burma.
''
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization An international organization (also known as an international institut ...
. .
There are few areas of wetland protected as national parks, but these are mostly very small.


Fish

The Chao Phraya Drainage basin, basin is home to around 280 species of fish, including about 30 Endemism, endemics.Freshwater Ecoregions of the World (2013).
Chao Phraya
.'' Retrieved 7 March 2015.
By far the most diverse family is Cyprinidae with 108 species. The mainstream of the Chao Phraya River has about 190 native fish species. In general, the aquatic fauna of Chao Phraya and
Mae Klong The Mae Klong (, , ), sometimes spelled Mae Khlong or Meklong, is a river in western Thailand. The river begins at the confluence of the Khwae Noi River, Khwae Noi (Khwae Sai Yok) and the Khwae Yai River (Khwae Si Sawat) in Kanchanaburi Province ...
show clear similarities, and they are sometimes combined in a single
ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including h ...
with 328 fish species. Despite their similarities, there are also differences between the aquatic fauna of Chao Phraya and Mae Klong; the latter (but not the former) is home to a few taxa otherwise only known in major Burma, Burmese rivers: the Irrawaddy River, Irrawaddy, Salween, and Great Tenasserim River, Tenasserim. The aquatic fauna in Chao Phraya–Mae Klong also show clear similarities with that of the middle Mekong (the lower Mekong fauna more closely resembles that of the eastern Malay Peninsula). It is believed that the upper Mekong was connected to Chao Phraya (rather than present-day lower Mekong) until the Quaternary, which explains the similarities in their river faunas. This included the
Nan River The Nan River ( th, แม่น้ำน่าน, , ) is a river in Thailand Thailand ( th, ประเทศไทย), historically known as Siam, () officially the Kingdom of Thailand, is a country in Southeast Asia. It is located ...
basin, a tributary of the Chao Phraya, which is home to a number of taxa (for example, ''Ambastaia nigrolineata'' and ''Sectoria'') otherwise only known from Mekong. Of the fish species known from the Chao Phraya–Mae Klong, only about 50 are absent from the Mekong. There has been extensive habitat destruction (pollution, dams, and drainage for irrigation) in the Chao Phraya basin and overfishing also presents a problem. Within mainland Southeast Asia, the only freshwater region with similar high levels of threat is the lower Mekong. It has been estimated that only around 30 native fish species still are able to reproduce in the mainstream of the Chao Phraya River. The catfish ''Platytropius siamensis'' is endemic to Chao Phraya and Bang Pakong River, Bang Pakong, but has not been recorded since the 1970s and is considered extinct. Recent records of the near-endemic cyprinid ''Balantiocheilos ambusticauda'' are also lacking and it is possibly extinct. Three of the List of largest fish, largest freshwater fish in the world are native to the river, but these are all seriously threatened: the critically endangered giant barb (wild populations have been Local extinction, extirpated from Chao Phraya, but remain elsewhere), critically endangered giant pangasius, and endangered giant freshwater stingray. The critically endangered red-tailed black shark, a small colourful cyprinid that is endemic to Chao Phraya, is commonly seen in the aquarium trade where it is bred in large numbers, but the only remaining wild population is at a single location that covers less than . The endangered dwarf loach, another species bred in large numbers for the aquarium trade, has been extirpated from most of its range in Chao Phraya. The critically endangered Siamese tigerfish has been entirely exirpated from Chao Phraya and Mae Klong, but small populations remain in the Mekong basin. Many other species that either are prominent in the aquarium trade or important food fish are native to the Chao Phraya basin, such as the Anabas testudineus, climbing perch, blue panchax, Pseudomystus siamensis, Asian bumblebee catfish, giant snakehead, striped snakehead, walking catfish, Syncrossus helodes, banded loach, several ''Yasuhikotakia'' loaches, tinfoil barb, Siamese algae eater, Java barb, silver barb, pearl danio, rainbow shark, Hampala macrolepidota, Hampala barb, black sharkminnow, ''Leptobarbus rubripinna'', Macrochirichthys macrochirus, long pectoral-fin minnow, Osteochilus vittatus, bonylip barb, Jullien's golden carp, blackline rasbora, Rasbora trilineata, scissortail rasbora, ''Tor tambroides'', Datnioides microlepis, finescale tigerfish, marble goby, Chinese algae eater, giant featherback, clown featherback, giant gourami, several ''Trichopodus'' gouramis, iridescent shark, several ''Pangasius'', ''Belodontichthys truncatus'', several ''Phalacronotus'' sheatfish, several ''Wallago'' catfish, largescale archerfish, smallscale archerfish, and wrestling halfbeak.FishBase:
Fish Species in Chao Phraya River.
' Retrieved 7 March 2015.


Pollution

The Thai Pollution Control Department (PCD) reports that the water quality of major rivers flowing into the upper Gulf of Thailand has seriously deteriorated in the past decade. The department found the lower Chao Phraya contains bacteria and nutrient pollution from phosphates, phosphorus, and nitrogen. Nutrient pollution causes algae to grow faster than ecosystems can handle, harming water quality, food resources for aquatic animals, and marine habitats. It also decreases the oxygen that fish need to survive. PCD rated water quality at the mouth of Chao Phraya at Bangkok's Bang Khun Thian District as "very poor", worse than in 2014. PCD findings indicated large amounts of wastewater were discharged into the river from households, industry, and agriculture.


See also

* River Systems of Thailand


References


Further reading

* ''Bangkok Waterways'', William Warren and R. Ian Lloyd, Asia Books, .


External links


Video Guide to the Chao Phraya River

Chao Phraya River Express

UNESCO World Water Assessment Program on the Chao Phraya



Bangkok Chao Phraya River Boat Trip
a self-guided boat trip on Bangkok's Chao Phraya river. {{Authority control Chao Phraya River, Rivers of Thailand Tropical and subtropical moist broadleaf forests Ecoregions of Asia