{{Short description|Major river in Thailand}} {{Redirect|Chao Phraya|the noble title|Thai nobility#Noble titles|the star|WASP-50}} {{Use American English|date=April 2012}} {{Use dmy dates|date=April 2021}} {{Infobox river | name = Chao Phraya River | native_name = {{native name|th|แม่น้ำเจ้าพระยา}} | name_other = | name_etymology = <!---------------------- IMAGE & MAP --> | image = Chao Phraya River - Bangkok - northwards - from King Taksin Bridge - 2021.jpg | image_size = 275px | image_caption = The Chao Phraya River in [[Bangkok]] | map = Chaophrayarivermap.png | map_size = | map_caption = Map of the Chao Phraya River drainage basin | pushpin_map = | pushpin_map_size = | pushpin_map_caption = | mapframe = yes | mapframe-zoom = 6 <!---------------------- LOCATION --> | subdivision_type1 = Country | subdivision_name1 = [[Thailand]] | subdivision_type2 = | subdivision_name2 = | subdivision_type3 = | subdivision_name3 = | subdivision_type4 = | subdivision_name4 = | subdivision_type5 = City | subdivision_name5 = [[Bangkok]] <!---------------------- PHYSICAL CHARACTERISTICS -->| length = {{convert|372|km|mi|abbr=on}} | width_min = | width_avg = | width_max = | depth_min = | depth_avg = | depth_max = | discharge1_location = [[Nakhon Sawan province|Nakhon Sawan]] | discharge1_min = | discharge1_avg = {{convert|718|m3/s|cuft/s|abbr=on}} | discharge1_max = {{convert|5960|m3/s|cuft/s|abbr=on}} <!---------------------- BASIN FEATURES -->| source1 = [[Ping River]] | source1_location = Doi Thuai, [[Chiang Mai province|Chiang Mai]] | source1_coordinates = {{coord|19|48|45|N|98|50|20|E|display=inline}}<ref name="source">{{cite web|url=http://www.thaiforestbooking.com/np_home.asp?npid=167&lg=2|title=Chiang Dao National Park|publisher=Thai Forest Booking|access-date=2009-05-20}}</ref> | source1_elevation = {{convert|1700|m|abbr=on}} | source2 = [[Nan River]] | source2_location = [[Bo Kluea district|Bo Kluea]], [[Nan province|Nan]] | source2_coordinates = {{coord|19|20|0|N|101|12|0|E|display=inline}} | source2_elevation = {{convert|1240|m|abbr=on}} | source_confluence = | source_confluence_location = [[Pak Nam Pho]], [[Nakhon Sawan province|Nakhon Sawan]] | source_confluence_coordinates = {{Coord|15.701|100.142|format=dms|display=i}} | source_confluence_elevation = {{convert|25|m|abbr=on}} | mouth = [[Gulf of Thailand]] | mouth_location = [[Thai Ban]], [[Samut Prakan province|Samut Prakan]] | mouth_coordinates = {{Coord|13.520|100.603|format=dms|display=i}} | mouth_elevation = {{convert|0|m|abbr=on}} | progression = | river_system = | basin_size = {{convert|160400|km2|abbr=on}} | tributaries_left = [[Pa Sak River]] | tributaries_right = [[Sakae Krang River]] | custom_label = | custom_data = | extra = }}
The '''Chao Phraya River'''{{efn|{{IPAc-en|ˌ|tʃ|aʊ|_|p|r|ə|ˈ|j|ɑː}}<ref>{{Cite dictionary |url=http://www.lexico.com/definition/Chao+Phraya |title=Chao Phraya |dictionary=[[Lexico]] UK English Dictionary |publisher=[[Oxford University Press]]}}{{dead link|date=September 2022|bot=medic}}{{cbignore|bot=medic}}</ref> or {{IPAc-en|tʃ|aʊ|ˈ|p|r|aɪ|ə}};<ref>{{MW|Chao Phraya}}</ref> {{langx|th|แม่น้ำเจ้าพระยา}}, {{RTGS|''Maenam Chao Phraya''}}, {{IPA|th|mɛ̂ː.náːm tɕâːw pʰráʔ.jāː|pron|Chaophraya.ogg}} or {{IPA|th|tɕâːw pʰrā.jāː|}})<ref>[http://www.forvo.com/word/แม่น้ำเจ้าพระยา/#th Pronunciation]</ref>}} ({{langx|th|แม่น้ำเจ้าพระยา}}) is the major river in [[Thailand]],<ref name="McCarthy" /> with its low [[alluvial plain]] forming the centre of the country. It flows through [[Bangkok]] and then into the [[Gulf of Thailand]].
==Etymology== Written evidence of the river being referred to by the name ''Chao Phraya'' dates only to the reign of King [[Mongkut]] (Rama IV, 1850–1868). It is unknown what name, if any at all, was used for the river in older times.<ref name="Silpa 2025">{{cite web |title=ทำไมเรียกแม่น้ำเจ้าพระยา สำรวจที่มาของชื่อ แม่น้ำเจ้าพระยา |author=((Silpa Wattanatham magazine editors)) |url=https://www.silpa-mag.com/history/article_24618 |website=Silpa Wattanatham |access-date=2 June 2025 |language=th |date=2 February 2025}}</ref> The river was likely known simply by the Thai word for 'river', {{lang|th|[[:wikt:แม่น้ำ|แม่น้ำ]]}} ({{RTGS|mae-nam|link=no}}), and foreign documents and maps, especially by Europeans visiting during the [[Ayutthaya period]], usually named the river the ''Menam''.<ref>{{cite book |author1=Kannika Suteerattanapirom |title=Bōrānnakhadī Krung Thon Burī |script-title=th:โบราณคดีกรุงธนบุรี |date=2022 |publisher=Matichon |location=Bangkok |isbn=978-974-02-1813-5 |language=th}} Excerpt in {{cite web |title=ย้อนร่องรอยแม่น้ำเจ้าพระยาในอดีต... |url=https://www.facebook.com/matichonbook/posts/6003291259735508/ |website=Matichon Book Facebook page |publisher=Matichon |access-date=2 June 2025 |date=27 December 2022}}</ref>{{efn|1=Irish [[surveyor]] and [[cartographer]] [[James McCarthy (surveyor)|James McCarthy]], [[F.R.G.S.]], who served as Director-General of the Siamese Government Surveys prior to establishment of the [[Royal Thai Survey Department]], wrote in his account, "Me Nam is a generic term, ''Me'' signifying "mother," and ''Nam'' "water," and the epithet Chao P'ia signifies that it is the chief river in the kingdom of Siam."<ref name=McCarthy>{{cite book |last= McCarthy |first= James Fitzroy |title= Surveying and exploring in Siam |url= https://archive.org/stream/surveyingandexp00mccagoog.pdf|date= 2005-07-13 |orig-date= 1900 |publisher= John Murray, Albemarle Street |location= London |oclc= 5272849 |page= 21|chapter= Chapter VI. From Bangkok to Korat – Elephants |chapter-url= https://ebooks.library.cornell.edu/cgi/t/text/pageviewer-idx?c=sea&cc=sea&idno=sea108&q1=tai&node=sea108%3A23&view=image&seq=37&size=100 |quote= The Mae Nam Chao P'ia is a magnificent river. |access-date=8 February 2012}}{{Dead link|date=August 2015}}</ref> [[Herbert Warington Smyth]], who served as Director of the Department of Mines in Siam from 1891 to 1896,<ref>{{cite web |url= http://www.pinetreeweb.com/hw-smyth-five-years-00.htm |title= Introduction to Five Years in Siam |access-date= 1 March 2011 |author= Tamara Loos |date= 1 December 2002 |work= 1994 reprint |publisher= Pine Tree Web |quote= At the time of writing the "Introduction" to the 1994 reprint of Five Years in Siam, she was a PhD candidate in the Department of History at Cornell University. |archive-url= https://web.archive.org/web/20101219111750/http://pinetreeweb.com/hw-smyth-five-years-00.htm |archive-date= 19 December 2010 }}</ref> refers to it in his book first published in 1898 as "the Mae Nam Chao Phraya".<ref>{{cite book |title=Five Years in Siam: from 1891–1896 |last=Smyth |first=H. Warington |year=1994 |orig-date=1898 |publisher=White Lotus |location=Bangkok |isbn=974-8495-98-1 |url=http://www.pinetreeweb.com/hw-smyth-five-years-01.htm |access-date=1 March 2011 |chapter=I. The river and port of Bangkok |archive-url=https://web.archive.org/web/20101219111526/http://pinetreeweb.com/hw-smyth-five-years-01.htm |archive-date=19 December 2010 }}</ref>}}
The name Chao Phraya likely comes from {{translit|th|rtgs|Bang Chao Phraya}} ({{lang|th|บางเจ้าพระยา}}), an alternative name, documented from around 1660 in the reign of King [[Narai]], of the settlement that is now [[Samut Prakan]]. Historian Praphat Chuvichean suggests that the name, which is a [[Thai noble titles|title of nobility]], originated from the story of two Khmer idols being unearthed in 1498 at the settlement that was by the mouth of the river at the time. When the delta extended further into the sea, a new settlement was founded to guard the new river mouth, and the new settlement probably gained the name Bang Chao Phraya (''bang'' being a common term for village names) as a reference to the memory of the idols.<ref name="Matichon 2016">{{cite news|title=บางเจ้าพระยา ชื่อเก่าก่อนแม่น้ำเจ้าพระยา |author=Praphat Chuvichean |department=Thongthin Mi Chumchon |newspaper=Siam Rath Daily |date=25 May 2016 |language=th}} Quoted in {{cite news |title="เจ้าพระยา" ในชื่อแม่น้ำเจ้าพระยา ได้จากเทวรูปขอม |author=Sujit Wongthes |url=https://www.matichon.co.th/columnists/news_176994 |access-date=2 June 2025 |work=Matichon Online |date=16 June 2016 |language=th}}</ref> There are references in records from the time of King [[Borommakot]] (r. 1733–1758) to {{translit|th|rtgs|Pak Nam Bang Chao Phraya}} ({{lang|th|ปากน้ำบางเจ้าพระยา}}, {{translit|th|rtgs|pak nam}} meaning 'river mouth'), suggesting that the name had become attached to the mouth of the river by that time,<ref name="Silpa 2025" /> and later became used for the entire river.<ref name="Matichon 2016" />
In the English-language media in Thailand, the name Chao Phraya River is often translated as ''river of kings''.<ref>{{cite web |url=http://www.speakingthai.com/stories/river%20king.htm |title=The River of Kings II: City of Angels |access-date=3 March 2011 |publisher=Thai Stories |quote="The River of Kings II – City of Angels", a light and sound musical |archive-date=12 June 2019 |archive-url=https://web.archive.org/web/20190612134203/http://speakingthai.com/stories/river%20king.htm }}</ref>
==History== {{Expand section|date=May 2025}} {{Unreferenced section|date=August 2022}} On the basins of Chao Phraya River rose the earliest civilizations in Southeast Asia, most notably the ancient Mon kingdom and the civilization of [[Dvaravati]] from the 7th century to the 11th century. The river played a crucial role in the [[Lavo kingdom]] that existed on its left bank in the Upper Chao Phraya valley and then maintained its role in the kingdoms that succeeded the Lavo kingdom. It formed the basis of the Ayodhya Kingdom, which was later incorporated into the [[Ayutthaya Kingdom]] in the 14th century, which itself was the precursor of modern Thailand (known formerly as Siam). The river became very significant after the establishment of Rattanakosin (Bangkok) in 1782 on its east bank, the location of Bangkok on the east bank of Chao Phraya River ensuring protection for Siam from the Burmese invasions coming from the west.
<gallery widths="200px" > File:Chao Phraya River in Siam (Ayutthaya) Map by Valentijn 1726.png|Chao Phraya River in Siam (Ayutthaya) Map by Valentijn 1726 File:Chao Phraya River Map from Ayutthaya 1751 Bellin.png|Chao Phraya River map from Ayutthaya in 1751 </gallery>
==Geography== The Chao Phraya begins at the [[confluence]] of the [[Ping River|Ping]] and [[Nan River|Nan]] rivers at [[Nakhon Sawan]] (also called Pak Nam Pho) in [[Nakhon Sawan province]]. After this, it flows south for {{convert|372|km|mi}} from the [[Central Thailand|central plains]] to [[Bangkok]] and the [[Gulf of Thailand]]. In [[Chai Nat province|Chai Nat]], the river then splits into the main course and the [[Tha Chin River]], which then flows parallel to the main river and exits in the Gulf of Thailand about {{convert|35|km|mi}} west of Bangkok in [[Samut Sakhon province|Samut Sakhon]].
In the low [[alluvial plain]] which begins below the [[Chao Phraya Dam]], there are many small canals (''[[khlong]]'') that 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 {{convert|1400|mm|in}} of rainfall per year. Temperatures range from {{convert|24|to|33|C|F}} in Bangkok.
===River engineering=== {{multiple image | align = right | total_width = 320 | image1 = Chaophrayashortcut.jpg | caption1 = The original course of the river and its shortcut canals | image2 = Khlong Bangkok Noi in Nonthaburi area.jpg | caption2 = [[Khlong Bangkok Noi]] in [[Nonthaburi province]] }}
The lower Chao Phraya underwent several human-made modifications during the [[Ayutthaya Kingdom|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]] of a {{convert|3|km|0|abbr=on}} long canal was dug at the order of [[Chairacha|King Chairachathirat]]. It was called "Khlong Lat", and today forms a part of [[Khlong Bangkok Noi]]. It shortened the route by 13–14 km for ships from the Gulf of Siam to the then-capital city, [[Ayutthaya (city)|Ayutthaya]].<ref name="ReferenceA">Steve Van Beek: ''The Chao Phya'', p.39</ref> * 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]]. It is said to have shortened the river route by {{convert|14|km|0|abbr=on}}.<ref name="ReferenceA"/> * In 1608, a seven-kilometer-long "Khlong Bang Phrao" canal was completed and has shortened the Chao Phraya's original route by {{convert|18|km|0|abbr=on}}.<ref name="ReferenceA"/> * In 1636, the "Khlong Lat Mueang Nonthaburi" was completed.<ref name="ReferenceA"/> * In 1722, the two-kilometre long "Khlong Lat Kret Noi" shortened the Chao Phraya by {{convert|7|km|0|abbr=on}}. This route formed the island of [[Ko Kret]].<ref name="ReferenceA"/> * In 2024 the 22-km-long "Chao Phraya II" channel was under construction. It will join the river at points to the north and south of Ayutthaya, providing flood relief for the city.<ref>"[https://www.nationthailand.com/in-focus/40013420 Chao Phraya II canal running through Ayutthaya on track, says official]", The Nation 2022-03-15, accessed 2024-12-28</ref>
==River settlements== Provinces along the Chao Phraya include, from north to south, [[Nakhon Sawan Province]], [[Uthai Thani Province]], [[Chai Nat Province]], [[Sing Buri Province]], [[Ang Thong Province]], [[Ayutthaya Province]], [[Pathum Thani Province]], [[Nonthaburi Province]], [[Bangkok]], and [[Samut Prakan Province]]. These cities are among the most historically significant and densely populated settlements of Thailand due to their access to the waterway.
==Transportation== {{See also|List of crossings of the Chao Phraya River|Chao Phraya Express Boat|Sathon-Klong Toei Express Boat}} [[File:Lunch at Rongros, Bangkok (Jan 2021) - img 05.jpg|thumb|[[Chao Phraya Express Boat]] on the Chao Phraya. [[Wat Arun]] is visible in the background.]] Major bridges cross the Chao Phraya in Bangkok: the [[Rama VI Bridge|Rama VI]] railroad bridge; [[Phra Pin-klao Bridge|Phra Pin-klao]] near the [[Grand Palace, Bangkok|Grand Palace]]; [[Rama VIII Bridge|Rama VIII]], a single tower asymmetrical cable-stayed bridge; [[Rama IX Bridge|Rama IX]], a semi-symmetric cable-stayed bridge; and [[Mega Bridge]], 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 [[commuter|commuter lines]].
==Tributaries== {{main|List of tributaries of the Chao Phraya River}}
[[File:Ang Thong - Chaiyo (2024) - Wat Chaiyo Worawihan วัดไชโยวรวิหาร - img 14.jpg|thumb|The Chao Phraya in [[Chaiyo District]], [[Ang Thong Province]]]] 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]].<ref name="RID River Gauges">{{cite web|url=http://157.82.150.160/GAME-T/GAIN-T/routine/rid-river/RIDstations.html |title=Royal Irrigation Department River Gauges Report |year=2002 |publisher=RID Stations |access-date=20 July 2008 |archive-url=https://web.archive.org/web/20090814235239/http://157.82.150.160/GAME-T/GAIN-T/routine/rid-river/RIDstations.html |archive-date=14 August 2009 }}</ref><ref name="WorldWater">{{cite web|url=http://www.unesco.org/water/wwap/case_studies/chao_phraya/index.shtml |title=Chao Phraya River Basin (Thailand) |publisher=World Water Assessment Programme |access-date=20 July 2008 |archive-url=https://web.archive.org/web/20080608214931/http://www.unesco.org/water/wwap/case_studies/chao_phraya/index.shtml |archive-date=8 June 2008 }}</ref><ref name="WorldWaterDetail">{{cite web|url=http://www.unesco.org/water/wwap/case_studies/chao_phraya/detailed_view.shtml |title=Detailed Map of the Chao Phraya River Basin (Thailand) |publisher=World Water Assessment Programme |access-date=20 July 2008 |archive-url=https://web.archive.org/web/20080918102553/http://www.unesco.org/water/wwap/case_studies/chao_phraya/detailed_view.shtml |archive-date=18 September 2008 }}</ref> 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]].<ref name="RID River Gauges" /> None of the tributaries of the Chao Phraya extend beyond the nation's borders.<ref name="Google Earth">Google Earth</ref> 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]].
==Length== [[File:Boatman on the Chao Phraya river in Nonthaburi province Thailand.jpg|thumb|Boat on the Chao Phraya in Nonthaburi]] When measured from the most commonly accepted source, which is the confluence of the Ping and Nan River in Nakhon Sawan, the river measures {{convert|372|km|abbr=on}}. However, when measured from the longest source, which is the origin point of the Nan River in the [[Luang Prabang Range]], the river measures {{convert|1112|km|abbr=on}}.
==Chao Phraya watershed== [[file:Watchaiwattanaram050617.jpg|thumb|Ruins of [[Wat Chaiwatthanaram]], built in [[Ayutthaya Kingdom]], by the Chao Phraya]]
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 [[drainage basin|watershed]].<ref name="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] {{webarchive |url=https://web.archive.org/web/20090104161404/http://www.premcenter.org/index.php?option=com_content&task=view&id=246&Itemid=830 |date=4 January 2009 }}</ref>
The Chao Phraya watershed is the largest watershed in Thailand, covering approximately 35 percent of the nation's land, and draining an area of {{convert|157924|km2}}.<ref name="Basins of Thailand">[http://en.pwa.co.th/l_basins.htm Basins of Thailand]{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
The watershed is divided into the following basins: *[[Pa Sak River|Pa Sak Basin]] *[[Sakae Krang River|Sakae Krang Basin]] *[[Nan River|Greater Nan Basin]] (composed of the [[Nan River|Nan Basin]] and the [[Yom River|Yom Basin]], and usually divided as such in drainage analyses) *[[Ping River|Greater Ping Basin]] (composed of the [[Ping River|Ping Basin]] and the [[Wang River|Wang Basin]], and usually divided as such in drainage analyses) *[[Tha Chin River|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 {{convert|20126|km2}} of land.<ref name="Basins of Thailand" />
To the west, the central plain of Thailand is drained by the [[Mae Klong]] and the east by the [[Bang Pakong River]]. 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]] 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 [[Drainage divide|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]] in the 13th and 14th centuries and the [[Ayutthaya Kingdom]] that succeeded it when rice growing intensified with the introduction of [[rice|floating rice]], a much faster-growing strain of rice from [[Bengal]]. The southern swamps meanwhile changed radically from the 18th century when King [[Buddha Yodfa Chulaloke]] 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== [[File:Mouth of Chao Phraya.jpg|thumb|The mouth of Chao Phraya River]] The [[Tha Chin River]] is the major distributary of the Chao Phraya River. The expanse of the Chao Phraya and [[Tha Chin River|Tha Chin]] 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 [[River delta|Delta]]. The many distributaries of the Chao Phraya delta are interconnected by canals that serve both for irrigation and transportation.
==Ecology== [[file:Bangrak Chaophya River.jpg|thumb|left|Human settlements along the Chao Phraya in [[Bang Rak]], [[Bangkok]]]] 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]] [[ecoregion]],<ref>{{WWF ecoregion|id=im0107|name=Chao Phraya freshwater swamp forests}}</ref> an area about {{convert|400|km|0|abbr=on}} north to south and {{convert|180|km|0|abbr=on}} 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]] (''Anhinga melanogaster''), [[white-eyed river martin]] (''Pseudochelidon sirintarae''), the [[sarus crane]] (''Grus antigone'')<ref>Madoc, G. 1950. Field Notes on some Siamese Birds. Bull. Raffles Mus. 23: 129–190.</ref> and animals such as [[tiger]]s, [[Asian elephant]]s, [[Javan rhinoceros]]es, and the much-hunted [[Schomburgk's deer]].<ref>IUCN 1991. The Conservation Atlas of Tropical Forests: Asia and the Pacific. London and Basingstoke: Macmillan Press Ltd.</ref> 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]]s on the coast and river estuaries. The swamp would have been covered in ''[[Phragmites]]'' marsh grasses. Today there is a small area of this remaining in [[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]] 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]]'', 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]] (''Anastomus oscitans''), and other birds such as the wintering [[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]] (''Hipposideros halophyllus'').
The Chao Phraya basin is home to about half a dozen endemic [[dragonflies]] and [[damselflies]]. The conservation status of most of these is unclear (they are rated as [[data deficient]] by the [[IUCN]]), but ''[[Cryptophaea saukra]]'' is [[critically endangered]] and ''[[Caliphaea angka]]'' is [[Endangered species|endangered]].<ref name=Allen2008>Allen, D.J.; Smith, K.G. & Darwall, W.R.T. (editors)(2008). ''[http://cmsdata.iucn.org/downloads/indo_burma_report_complete_low_res_28_aug.pdf The status and distribution of freshwater fishes of Indo-Burma.] {{webarchive |url=https://web.archive.org/web/20160729182912/http://cmsdata.iucn.org/downloads/indo_burma_report_complete_low_res_28_aug.pdf |date=29 July 2016 }}'' [[IUCN]]. {{ISBN|978-2-8317-1424-0}}.</ref>
There are a few areas of wetland protected as national parks, but these are mostly very small.
===Fish=== [[File:Giant Barb.jpg|thumb|The [[giant barb]] is one of the world's largest freshwater fish weighing up to {{convert|300|kg|lb|abbr=on}},<ref name=Fishbase>{{FishBase | genus = Catlocarpio | species = siamensis | year = 2015 | month = March}}</ref> but the natural population has been [[Local extinction|extirpated]] from Chao Phraya.<ref name=IUCNCatlocarpio/>]]
The Chao Phraya [[Drainage basin|basin]] is home to around 280 species of fish, including about 30 [[Endemism|endemics]].<ref name=FEOW>Freshwater Ecoregions of the World (2013). ''[http://www.feow.org/ecoregions/details/chao_phraya Chao Phraya] {{webarchive |url=https://web.archive.org/web/20160304192924/http://www.feow.org/ecoregions/details/chao_phraya |date=4 March 2016 }}.'' Retrieved 7 March 2015.</ref> By far the most diverse family is [[Cyprinidae]] with 108 species.<ref name=FEOW/> The mainstream of the Chao Phraya River has about 190 native fish species.<ref name=Allen2008/> In general, the aquatic fauna of Chao Phraya and [[Mae Klong]] show clear similarities, and they are sometimes combined in a single [[ecoregion]] with 328 fish species.<ref name=Allen2008/> 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]].<ref name=Allen2008/> 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]]).<ref name=Allen2008/> It is believed that the upper Mekong was connected to Chao Phraya (rather than the present-day lower Mekong) until the [[Quaternary]], which explains the similarities in their river faunas. This included the [[Nan River]] basin, a tributary of the Chao Phraya, which is home to several taxa (for example, ''[[Ambastaia nigrolineata]]'' and ''[[Sectoria]]'') otherwise only known from Mekong.<ref name=Allen2008/> Of the fish species known from the Chao Phraya–Mae Klong, only about 50 are absent from the Mekong.<ref name=Allen2008/>
[[File:Epalzeorhynchos bicolor.jpg|thumb|The only remaining wild population of the [[red-tailed black shark]] is restricted to an area of less than {{convert|10|km2|mi2|abbr=on|0}}.<ref name=IUCNEpalzeorhynchos/>]]
There has been extensive habitat destruction (pollution, [[dam]]s, and [[drainage]] for [[irrigation]]) in the Chao Phraya basin and [[overfishing]] also presents a problem.<ref name=Allen2008/><ref>Samorn Muttamara, S. & Sales, C. L. (1994). ''Water quality management of the Chao Phraya River (a case study).'' Environmental Technology 15(6).</ref><ref>Molle, F. (2005). ''Elements for a political ecology of river basins development: The case of the Chao Phraya river basin, Thailand.'' Paper presented to the 4th Conference of the International Water History Association, December 2005, Paris.</ref><ref>Chuenpagdee, R.; Traesupap, S. & Juntarashote, K. (2010). ''Coastal Transect Analysis of Chao Phraya Delta, Thailand''. pp. 398-407 in: Hoanh, C.T. & Szuster, B.W. (editors). ''Tropical Deltas and Coastal Zones: Food Production, Communities and Environment at the Land-water Interface.'' {{ISBN|9781845936181}}.</ref> Within [[mainland Southeast Asia]], the only freshwater region with similar high levels of threat is the lower Mekong.<ref name=Allen2008/> It has been estimated that only around 30 native fish species still can reproduce in the mainstream of the Chao Phraya River.<ref name=Allen2008/>
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]].<ref>{{Cite iucn | author = Ng, H.H. | title = ''Platytropius siamensis'' | volume = 2011 | article-number = e.T180996A7657156 | date = 2011 | doi = 10.2305/IUCN.UK.2011-1.RLTS.T180996A7657156.en | access-date = 9 January 2018}}</ref> Recent records of the near-endemic cyprinid ''[[Balantiocheilos ambusticauda]]'' are also lacking and it is possibly extinct.<ref name=Allen2008/><ref>{{Cite iucn | author = Vidthayanon, C. | title = ''Balantiocheilos ambusticauda'' | volume = 2011 | article-number = e.T180665A7649599 | date = 2011 | doi = 10.2305/IUCN.UK.2011-1.RLTS.T180665A7649599.en | access-date = 9 January 2018}}</ref> 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),<ref name=IUCNCatlocarpio>{{Cite iucn | author = Hogan, Z. | title = ''Catlocarpio siamensis'' | volume = 2011 | article-number = e.T180662A7649359 | date = 2011 | doi = 10.2305/IUCN.UK.2011-1.RLTS.T180662A7649359.en | access-date = 9 January 2018}}</ref> critically endangered [[giant pangasius]],<ref>{{Cite iucn | author = Jenkins, A., Kullander, F.F. & Tan, H.H. | title = ''Pangasius sanitwongsei'' | volume = 2009 | article-number = e.T15945A5324983 | date = 2009 | doi = 10.2305/IUCN.UK.2009-2.RLTS.T15945A5324983.en | access-date = 9 January 2018}}</ref> and endangered [[giant freshwater stingray]].<ref>{{Cite iucn |author1= Vidthayanon, C. |author2=Baird, I. |author3=Hogan, Z. | title = ''Urogymnus polylepis'' | volume = 2016 | article-number = e.T195320A104292419 | date = 2016 | doi = 10.2305/IUCN.UK.2016-3.RLTS.T195320A104292419.en | access-date = 9 January 2018}}</ref> 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 {{convert|10|km2|mi2|abbr=on|0}}.<ref name=IUCNEpalzeorhynchos>{{cite iucn |author=Vidthayanon, C. |date=2011 |title=''Epalzeorhynchos bicolor'' |volume=2011 |article-number=e.T7807A12852157 |doi=10.2305/IUCN.UK.2011-1.RLTS.T7807A12852157.en |access-date=13 November 2021}}</ref> 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.<ref>{{cite iucn |author=Vidthayanon, C. |date=2011 |title=''Yasuhikotakia sidthimunki'' |volume=2011 |article-number=e.T2953A9501746 |doi=10.2305/IUCN.UK.2011-1.RLTS.T2953A9501746.en |access-date=13 November 2021}}</ref> The critically endangered [[Siamese tigerfish]] has been entirely extirpated from Chao Phraya and Mae Klong, but small populations remain in the Mekong basin.<ref>{{cite iucn |author=Vidthayanon, C. |date=2011 |title=''Datnioides pulcher'' |volume=2011 |article-number=e.T180969A7656475 |doi=10.2305/IUCN.UK.2011-1.RLTS.T180969A7656475.en |access-date=13 November 2021}}</ref>
[[File:Basa fish - Vinh Long Market.jpg|thumb|[[Basa fish]] from the Chao Phraya and Mekong is an important food fish, and it is also [[Fish farming|farmed]].<ref>{{Cite iucn | author = Vidthayanon, C. | title = ''Pangasius bocourti'' | volume = 2012 | article-number = e.T180848A1669669 | date = 2012 | doi = 10.2305/IUCN.UK.2012-1.RLTS.T180848A1669669.en | access-date = 9 January 2018}}</ref>]]
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|small-scale archerfish]], and [[wrestling halfbeak]].<ref>FishBase: ''[https://web.archive.org/web/20150404152822/http://www.fishbase.org/identification/RegionSpeciesList.php?SortBy=family&e_code=161&resultPage=1 Fish Species in Chao Phraya River.]'' Retrieved 7 March 2015.</ref>
===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, and the lower Chao Phraya contains bacteria and [[nutrient pollution]] from [[phosphate]]s, [[phosphorus]], and [[nitrogen]]. Nutrient pollution causes [[algae bloom|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 in Bangkok's [[Bang Khun Thian District]] as "very poor", worse than in 2014, and their findings indicated large amounts of wastewater were discharged into the river from households, industry, and agriculture.<ref name="PCDR-2015">{{cite book|title=Thailand State of Pollution Report 2015|publisher=Pollution Control Department|location=Bangkok|isbn=978-616-316-327-1|url=http://infofile.pcd.go.th/mgt/PollutionReport2015_en.pdf?CFID=2140989&CFTOKEN=61488210|access-date=23 September 2016|archive-date=5 September 2017|archive-url=https://web.archive.org/web/20170905191033/http://infofile.pcd.go.th/mgt/PollutionReport2015_en.pdf}}</ref><ref name="BP-20160925">{{cite news|last1=Wangkiat|first1=Paritta|title=Breach of trust|url=http://www.bangkokpost.com/news/special-reports/1094405/breach-of-trust|access-date=25 September 2016|work=Bangkok Post|date=25 September 2016}}</ref> In addition, 4,000 metric tons of plastic flow down the river into the Gulf of Thailand every year. To counter this, Thailand's Department of Marine and Coastal Resources (DMCR) signed an agreement with [[The Ocean Cleanup]] organization to deploy an Interceptor Original, one of the organization's solar-powered, automated systems, in the river. Since 19 February 2024, an interceptor of the latest third generation has been deployed for testing purposes.<ref>{{Cite web|url=https://www.newsecuritybeat.org/2022/06/plastic-river-waste-thats-choking-chao-phraya/|title=Plastic River: Following the Waste That's Choking the Chao Phraya|website=newsecuritybeat.org|date=16 June 2022 }}</ref><ref>{{Cite web |title=Interceptor 19 installed for testing |url=https://theoceancleanup.com/dashboard/#interceptor019 |website=theoceancleanup.com}}</ref>
==See also== * [[River Systems of Thailand]] * [[Kapuas River]]
==Notes== {{Notelist}}
==References== {{Reflist}}
==Further reading== * ''Bangkok Waterways'', William Warren and R. Ian Lloyd, Asia Books, {{ISBN|981-00-1011-7}}.
==External links== {{Commons category|Chao Phraya|Chao Phraya River}} * [http://www.thailand.tv/watch/chao-phraya-river Video Guide to the Chao Phraya River] * [https://web.archive.org/web/20060210041118/http://www.chaophrayaboat.co.th/ Chao Phraya River Express] * [https://web.archive.org/web/20080608214931/http://www.unesco.org/water/wwap/case_studies/chao_phraya/index.shtml UNESCO World Water Assessment Program on the Chao Phraya] * [https://web.archive.org/web/20071107093034/http://std.cpc.ku.ac.th/delta/conf/home2.htm Chao Phraya Delta Research and Reference Site] * [http://bangkok-boat-trip.blogspot.com/ Bangkok Chao Phraya River Boat Trip] a self-guided boat trip on Bangkok's Chao Phraya river.
{{coord|13|32|25|N|100|35|23|E|region:TH-11_type:river_source:kolossus-etwiki|display=title}} {{Authority control}}
[[Category:Chao Phraya River| ]] [[Category:Rivers of Thailand]] [[Category:Tropical and subtropical moist broadleaf forests]] [[Category:Ecoregions of Asia]]