49 Geomorphology of the Chao Phraya River Basin The Ping, Wang, Yom and Nan rivers flow from the furrowed mountain and valley landscape of northern Thailand before merging at Nakhon Sawan to form the Chao Phraya River. Lo-cated at the headwaters of the Chao Phraya, the Northern King-doms of Chiang Mai, Lampang and Nan constitute a network of political tributary states at times under the sovereignty of successive capitols at Sukhothai, Ayutthaya and Bangkok. At Chainat, the Chao Phraya splits into the meandering braids of the Tha Chin, Noi and Lopburi rivers that flow through numer-ous canals before joining the Pasak River at the base of the old delta at Ayutthaya. Japanese agronomist Yoshikazu Takaya (1975) has developed an ecological interpretation of Thai his-tory that traces historical development geographically down-stream from the mountains, to the floodplain of the old delta and the new delta. According to Takaya, the economy and ur-banization of Thailand was historically dependent on irrigation and monsoon-based rice production. The size and power of a polity was tied to the tributary’s accumulated area of water and its distribution in successively larger catchments. Upstream set-tlements ( muang  ) with smaller valleys received less water and nutrient resources than the larger intermountain valleys and successive capitols. The accumulation of water downstream is paralleled by the accumulation of power over several centuries.This tributary political system matched the hydrology of the territory, and upstream vassals delivered tribute to downstream kings, but remained politically autonomous. Contact with the colonial powers, especially Great Britain and France, result-ed in the King of Siam’s acceptance of surveyed and mapped boundaries between Siam, British Burma, Malaysia and French Indochina (now Laos and Cambodia) at the end of the nine-teenth century. While Benedict Anderson (1983) identifies the promulgation of national languages, censuses, and print and media technologies in creating the ‘imagined community’ of the nation-state, Thongchai Winichakul (1994) adds mapping to this list to create an imagined national ‘geo-body’. Previously, a ‘water-body’ dominated the cultural and political imagina-tion of precolonial Southeast Asia, but entered a slow decline following construction of the nation-state’s bounded territory [ Thaitakoo and McGrath 2008  ]. Chao Phraya Delta Land Cover The satellite image reveals dark red wedges radi-ating from the west bank of the river and oxbow islands indicating the dense tree cover of remnant mixed canopy orchards. The paler, large red rec-tangular tracks on the east bank are predominately rice fields. Industrial estates (in white) are clustered primarily north and east of the city centre. 48   The vast territory of the Lower Chao Phraya River Delta, the geo-morphological context within which the contemporary Bangkok megacity sprawls, has been the site of indigenous water-based urbanism for centuries before the founding of the royal city in 1782. In addition to the meandering Chao Phraya, Bangkok Met-ropolitan Area (BMA) there are 1,682 canals stretching 2,600 km. This water network includes three additional rivers draining into the Gulf of Thailand, and 54 major canals over 20 m wide. The network comprises an integral part of the city’s storm water man-agement system that also includes dykes, underground tunnels, retention ponds and pumps [ Phamornpol 2013 ]. Today a constellation of industrial estates rings the city, as Bangkok’s role is not just political centre but economic engine of Thailand. While export rice cultivation financed the rise of the modern Kingdom, Thailand has tied development to export industry since 1950. As a result, the ‘distributary’ water system of the urban-agricultural delta transformed from the cultivation of rice to a global network for exporting electronics and automo-biles. While historically, the canal and river network was the heart of the cultural and economic life of the Chao Phraya Delta, in the industrialized landscape it is often just imagined as an outlet for drainage.The historical development of Siamese urbanism evolved from a tributary political system that followed the course of the Chao Phraya River from the northern valley kingdoms to the successive capitals at Sukhothai, Ayutthaya and Bangkok [ McGrath 2007  ]. Indigenous water management knowledge is documented in scores of social, ethnographic and historical ac-counts briefly outlined here. However, socio-ecological research and local knowledge was rarely put to use in the planning of modern water control systems. This chapter traces the historical course of Siamese water-based urbanization along the path of the catastrophic 2011 flood in Thailand. Cutting back and forth between past and present, we aim to identify the rich history of water-based urbanisms and contrast the problems that ensued after World War II with the adoption of modern engineering techniques to control floods. As Thailand recovers and rebuilds, new water management and larger scale engineering solutions need to be aligned with indigenous water management knowl-edge. BRIAN MCGRATH | TERDSAK TACHAKITKACHORN | DANAI THAITAKOO Bangkok’s Distributary Waterscape Urbanism From a Tributary to Distributary System  The vast young delta below Ayutthaya was formed 10,000 years ago after the glacier retreat of the last ice age [ Sin 2000 ]. The lower deltaic plain was completely inundated in the rainy sea-son and became a parched desert during the dry season. This al-ternating swampy and arid landscape did not provide a suitable environment for human habitation like the upstream valleys [ Jarupongsakul & Kaida 2000 ]. When the tributary rivers reach the flat plains, both within the old and new deltas, they un-braid and meander into multiple courses, following a distribu-tary rather than a tributary logic. Natural levees along the slow moving meanders provide settlement areas higher than the land behind, where wet rice could be cultivated in the low-lying backwaters. The levee system was enlarged to provide fruit and shade trees around settlements. Periodic flooding sometimes resulted in breeches of levees and changes to the courses of the rivers were common, leaving remnant ox-bow lakes. Settlers learned from living with water cycles and forms to cut canals for diversion, irrigation, retention, transportation and defence and created artificial levees for larger settlements. The Chao Phraya and Tha Chin rivers constituted the twin spines of the lower old delta, but the network connects to the Mae Klong River from the west and the Bang Pakong River to the east.In the lower Chao Phraya River, the combination of heavy monsoon outflows from upstream tributaries, the local inun-dations within the low, flat plain and the heavy pressure from high tides, together constitute Bangkok as ‘the city of three wa-ters’ [ Van Beeck 1995 ]. Combinations of heavy rainfall and high tides in the months of October or November invariably result in floods. While a modern technological infrastructure of irri-gation and flood control has been institutionalized in Thailand since 1910, it is often at cross-purposes with the indigenous building and farming systems that were designed to accommo-date large fluctuations in water levels. It is this ‘perfect storm’ of excess water from the north demanding release from upstream dams, heavy monsoon rains and high tides that conspired in Oc-tober 2011. As the modern drainage system is superimposed and utilizes the historical waterscape urban structure, dykes and flood gates became the sites of social conflict during the flood. Gulf of Thailand Chao Phraya   Suphan   Noi   Chao Phraya   Nakorn Chaisi Chao Phraya   Tachin   Lopburi Pasak Nakorn nayok Maeklong Bangpakong Tup NangCanalSamrongCanalMahachai CanalMaenam OhmPak KretPath of Chao Phraya afterAngthongCanal wasdug.BangKaeo Section of    Old Chao Phraya Hydraulic Projects of the Kingdom of Ayutthaya (1350–1767) Existing waterway   Ayutthaya (1350–1767) Bangkok  AyutthayaChainat  Ayutthaya Era Canals Canal construction between the mid- 14th and 19th centuries created an artificial island city at the con-fluence of three rivers and short-cuts to the Gulf to ease maritime trade across Asia and Europe. BANGKOK’S DISTRIBUTARY WATERSCAPE URBANISM   51   Intermountain basinsFan-Terracecomplex areaPlugged riverchannel areaOld deltaDeltaichighDelta flatNon-riceland   Mountains IntermontaneBasinsFan-terracecomplexFloodplainOld DeltaYoungDelta : : : : ChiangMai Sukhothai Ayutthaya Bangkok Sukhothai:Fan TerraceModelChiangMai:IntermontaneBasin ModelAyutthaya:RiverConfluenceModelBangkok:Delta Model  Thailand’s Water Cities Chiang Mai is an intermountain tributary waterscape urban model, set back from the Ping River with a water supply, drainage and defensive moat fed by a mountain stream. Sukhothai is built at the site of a Khmer outpost located on a fan terrace within the floodplain of the Yom River. Ayutthaya is an island city at the confluence of three rivers, and Bangkok is a delta city near the mouth of the sea. Chao Phraya Watershed Tributary and Distributary System The tributary rivers Ping, Wang, Yom and Nan flow from the mountains of northern Thailand and come together to form the Chao Phraya River near Nakhon Sawan. From there, branches, loops and canals form a braided distributary network in the central basin of Thailand and its vast delta, with the ancient island city of Ayutthaya at the choke point of the rivers’ confluence. 50  0 50 100 km0 50 100 km0 10 20 40 km  large-scale royal infrastructure projects with micro-scale, com-munity based water management [ Terdsak 2005 ]. The lower del-ta combined the best alluvial ingredients: a brackish mix of sea and freshwater and comprised ‘rice-fish-fruit-poultry complex’ [ Kaida n. d. ]. The Chao Phraya is distinguished as a mercantile delta with dynamic economic motives as opposed to a primar-ily agricultural delta where community stability is privileged.This territorial water infrastructure was further consti-tuted by a micro-ecological matrix of orchard and rice paddy modular units, which remain the parcel substructure for much modern development today. The centuries old delta peri-urban system, consisting of a porous mix of urban and agricultural patches identified by T. G. McGee as ‘desakota’, is common to the cities of South-East Asia [ McGee 1991 ]. Recent remote and ground-based surveys, combined with archival research from the Faculty of Architecture at Chulalongkorn University with Parsons The New School for Design, has revealed both the socio-ecological practices of this vast historical urban region and its degradation due to modern road-based export indus-trial development. Together we are outlining design scenarios to better integrate new mega-development with the ‘practical ecology’ [ Tanake 1994 ]. Bangkok Delta City After the Burmese invasion and catastrophic destruction of Ayutthaya, the Kingdom of Siam was reorganized from 1767 to 1780 under King Thaksin at the capitol of Thonburi on the west bank of the short-cut canal, now the main course of the Chao Phraya. Rama I, the first monarch of the present-day Chakri dynasty, founded Bangkok on the east bank in 1782. The new royal city is a moated enclave modelled on Ayutthaya, with two north–south canals forming mirrored bows to the main course of the river to the west. One island housed the Grand Palace for the King and the Front Palace for the Second King, as well as the most important Buddhist temples and mon-asteries.East–west defensive canals were constructed with a labour force from neighbouring states—the Bangkapi and San Saeb to the east, connecting the outer moat of the city to the Bang Kapong River, and to the west, extending the canals that linked the Chao Phraya to the Tha Chin and Mae Klong rivers. At Bangkok, the Kingdom quickly recovered from the defeat of Ayutthaya. Now located even closer to sea trade, the Siamese water-based agricultural economy was still intact, with an en-larged canal defensive, irrigation and transportation system.Yoshihiro Kaida [1974] identifies six different types of ur-banization patterns in his study, ‘Pioneer Settlements and Water Control Development on the West Bank of the Lower Chao Phraya Delta’. Four are linear ‘ribbon’ developments that form urban strands along the water market network of the nat-ural levees of the rivers, man-made canals, scattered hamlets along smaller natural streams, and the Chinese fruit and veg-etable growers in the tidal delta. The other two are dispersed types that cluster as patch settlements around ponds that form villages in the upper fan-terrace complex and single house lots in the lower delta. An evergreen canopy covering the houses characterizes both linear levee and patch pond settlements. It is within this settlement matrix that the present industrial es-tates are superimposed, creating a patchwork of factories and farms linked by highways above and canals below. BANGKOK’S DISTRIBUTARY WATERSCAPE URBANISM   53  Ayutthaya: Confluence City Ayutthaya, the capitol of Siam from 1351 to 1767, is located 70 km north of Bangkok. As a major global trading centre, fifteenth-century Ayutthaya became the dominant city of Southeast Asia following the long slow decline of Angkor from 1290 to 1431 [ Wyatt 1984 ]. Ayutthaya’s urban influence spread through a vast natural and artificial network in the lower delta, and its urban form responds directly to the ‘local genius’ of regional water dynamics [ Prapod 2012 ]. While Angkor Thom was created at a small stream a respectful distance from the sea-sonally flooded Tonle Sap lake, Ayutthaya occupies an island formed at the hydrological choke point of the major tributaries to Chao Phraya. Evidence even points to the possibility that Ayutthaya was not founded at the confluence of these rivers; instead, the builders of the city redirected the rivers to create the great confluence [ Van Beeck 1995 ]. The ancient capitol was strategically positioned at the head of a widely dispersed water-based productive landscape comprised of fruit orchards and sugar cane and rice farms that reached deep into the lower del-ta [ Terdsak 2005 ]. River- and canal-side market towns through-out the delta were integrated into a world trading system. The farms and markets formed a network and substructure that underlies the land division pattern of Bangkok’s sprawling modern mega-region.During the Ayutthaya period, a distributary water-based Siamese urbanism developed along both north–south short cuts to the sea and east–west transversal defensive canals reaching to Bangkok, the future capital of the Kingdom. In the 1970s the peri-urban area spanning Ayutthaya and Bangkok be-came an industrial logistical hub between upcountry labourers and international markets. With the release of water from up-stream dams, they were particularly vulnerable to inundation in the 2011 monsoon. Flooding of a huge Honda plant and the Nava Nakhorn high-tech industrial zone put automobile and electronic global supply chains at risk. The floods even shut seven large industrial zones, closing hundreds of factories and putting hundreds of thousands of jobs at risk. Lower Chao Phraya Delta: A Distributary Network During the height of Ayuttaya’s power, a series of short-cut canals were designed to bypass several of the Chao Phraya oxbows on the way to the sea. These include, from north to south, Kret Yai, Yong, Lad Muang Non, Lad Krung Thep (the present riverfront of Bangkok) and Lad Pho canals. Addition-ally, transversal canals—the Yong and the Do—connected the Chao Phraya to the Tha Chin River to the east, while the Samrong and Tup Nang connected with the eastern seaboard. While these new additions to the delta’s distributary network were built for trade and defensive logistical purposes, they in-duced settlement along the artificial levees. Often conscripted corvée chose to settle in the now inhabitable landscape [ Hub- bard and Hafner 1973 ]. It is this canal network that forms the main spines of Bangkok urbanization historically. They are the critical arteries of BMA’s flood control plan.Canal and riverside settlements were based on an orchard structure that combined the canal network with irrigated qua-nat units (polder-like micro water basins with a corrugated soil mound structure, alternating bands of ridges for the fruit trees and furrows for the water). This structure provided the best balance between land and waterscape and supplemented the 52    Gulf of Thailand Chao Phraya Suphan Noi Chao Phraya Nakorn Chaisi Chao Phraya Tachin Lopburi Pasak Nakorn Nayok Maeklong Bangpakong Sunak Hawn CanalSaen Saeb CanalBangKhanak Canal Hydraulic Project Thonburi andEarly Bangkok Periods (1767–1851) Bangkok  AyutthayaChainat   Gulf of Thailand Chao Phraya Suphan Noi Chao Phraya Nakorn Chaisi Chao Phraya Tachin Lopburi Pasak Nakorn nayok Maeklong Bangpakong RangsitCanal Hydraulic Project The Reign of Rama V (186   8–1910) ExistingwaterwayAyutthaya (1350–1767)Thonburi(1767–1851) Rama IV(1851–1868)Rama V(1868–1910) NewWaterWayProjects Bangkok  AyutthayaChainat Bangkok Map The detail from a much larger map shows the royal island city embedded in the agricultural matrix con-sisting of orchard qanat units on the west bank with rice fields on the east. Two new additions to the city, Dusit to the north and Pathumwan to the east of the royal island enclave, were the first additions planned with roads. Early Bangkok Era Canals The early Bangkok era canals were built primarily for military purposes. The long east–west canals link the major rivers of the delta to each other and allow the movement of troops to the eastern and western frontiers of the Kingdom with roads. King Chulalongkorn Era Canals Canal construction during the rice production for export was the main source of income for modern-izing King Chulalongkorn. Property rites were ceded to land companies that built irrigation and trans-portation canals, most significantly in the gridded Rangsit area north-east of Bangkok. BANGKOK’S DISTRIBUTARY WATERSCAPE URBANISM   55 0 10 20 40 km0 10 20 40 km  Bangkok Territorial Map A mosaic of historical maps of Chao Phraya River Delta (circa 1906 –1941) illustrate a natural pattern of deltaic topography, natural courses of rivers and settlement based upon their relationship with hydro-ecological conditions of the deltaic landscape. The interpolation of human inter-vention on the natural landscapes such as networks of irrigation canals, transportation canals, and land- based transportation networks is also depicted. Colonial Contact and Export Rice Infrastructure By the middle of the nineteenth century, contact and trade agreements with European colonial powers brought new ur-ban forms to Bangkok such as streets lined with shop-houses. The Royal Privy Purse pursued development of shop-house rows in streets around princely palaces and monasteries under King Rama IV (1851 – 68) and Rama V (1868 – 1910) as trade was ex-panded beyond royal monopolies. Sugar was the first plantation crop developed for export, but rice quickly assumed the role of the primary cash crop of the Kingdom with urban markets such as Singapore and Hong Kong demanding imported food. Rice grew from 10,000 tons annually to 1 million tons approaching 75 per cent of total export value by 1914 [ Falkus 1993 ]. While the centre city added a shop-house-lined road system to compliment the canal structure, the delta as a whole saw a massive increase of the water infrastructure, with private canal developers awarded 8 km of land rights at either side of a con-structed canal. The locally managed system of rice farming was modernized beginning when King Rama V created the Royal Irrigation Department in 1902, and Dutch engineer Homan van der Heide, recruited from Netherlands Indonesia, became its first director until 1909. Van der Heide proposed an ambi-tious plan for economic development that would significantly increase the wealth of the nation through the construction of an irrigation and drainage system in the Chao Phraya River Delta [ Brummelhuis 2007  ]. Together with the end of the corvée systems, a hydro-economy of small village-based farming was developed. Van der Heide worked to develop a dependable ir-rigation and drainage system that would maintain water supply throughout the year. Although the full plan was not executed, extensive canal construction was undertaken during this pe-riod including the north–south Prem Pachakorn Canal that was cut east and parallel to the Chao Phraya and connected to the vast grid of irrigated rice fields in the Rangsit area northeast of Bangkok. Such a favourable hydro-economy extended the duration and area of rice cultivation. The quality and quantity of rice could be improved under the hydro-economy; major canals and their branches would deposit more silt on the plots, thus fertilizing the fields. Moreover, flooding of villages and gardens could be prevented and, as a result, orchard lands could be expanded and fruit production improved. Pure drinking water became avail-able throughout the region during the whole year. Finally, the extensive network of canals improved transportation that in-cluded road building on the embankments [ Brummelhuis 2007  ].Rama IV extended the city in the traditional pattern with the construction of a third ring canal in the mid-nineteenth century. However, Rama V’s extensions to the city at the turn of the twentieth century were the first road-based expansions. To the north he built the Dusit District around a new palace and throne hall, and to the east he built the Pathumwan District around a palace for the newly installed Crown Prince. The road system was superimposed over the canal network, and every new road also had a parallel drainage canal. Some roads, in fact, were the result of fill from canal dredging. Maps from the turn of the twentieth century show a garden city of new palaces sur-rounded by significant areas of surface water present in canals, moats and ornamental retention ponds. 56  BANGKOK’S DISTRIBUTARY WATERSCAPE URBANISM