|THE NOI: SILTED RIVER OF KINGS
|Text & photographs by Tricky Vandenberg - August 2011
The Noi River or Chao Phraya Noi (little Chao Phraya) is one of the three tributaries of
the Chao Phraya River. The latter is formed by the confluence of four rivers at Nakhon
Sawan being the Ping, the Nan, the Wang and the Yom. The Sakae Krang River joins the
Chao Phraya at Krok Phra district in Uthai Thani province. The Chao Phraya gives birth to
three new rivers: the Tha Chin River also called the Suphan River, the Noi River and further
downstream the Lopburi River; starting in fact a delta at Chai Nat.
The Noi River branches off from the Chao Phraya River about 5 Km south of Chai Nat. It
is one of the former courses of the Chao Phraya itself. The Chao Phraya initially flowed
west of its present course beginning just below Chai Nat and running to Ang Thong via
Sankha Buri, Bang Rajan and Pho Thong. The river must then have breached its west bank
near Ang Thong because in its route it ran south-west from Ban Intha-Pramun via Wiset
Chai Chan, Phak Hai, and Sena, and entered its present-day channel at Bang Sai.
After some time, the river bed of the Chao Phraya over Sankha Buri appears to have silted
up and the river shifted to the east. The Chao Phraya broke its east bank near Chai Nat,
flowing nearly north-east for 12 kilometers before turning south, approximating the Chao
Phraya’s present course from Chai Nat to Ang Thong. In 1857 the Chao Phraya River
took a new course from Ang Thong to Ayutthaya, due to man-made channel works. The
old river bed from Chai Nat over Ang Thong and Sena to Bang Sai became as thus known
as the Chao Phraya Noi. The latter re-enters the Maenam at Wat Bang Sai. 
The Noi River starts at an altitude of 21 meters ASL near Chai Nat and ends up at an
altitude of 3 meters ASL at its confluence near Bang Sai after a run of 170 Km through the
central flood plains. The author paddled down the Noi River and gathered following
Homan Van der Heide, an irrigation engineer from Holland, was employed in June 1902
during the reign of King Rama V as an expert on irrigation and advisor for the improvement
of the irrigation system in the lowlands of the Chao Phraya delta. Van der Heide proposed
to the Siamese government to improve the water reserve system together with an efficient
system of irrigation by building a dam across the Chao Phraya River in Chai Nat Province
and to supply the conserved waters into the Suphan and the Noi Rivers.
|(Map from Chao Phya in Transition - Steve
|The Chao Phraya Bassin
(Map from http://www.riversoftheworld.org/11664)
The Boromma That water regulator is the barrier at the confluence with the Chao Phraya
River and controls as thus the water inflow diverted from the Chao Phraya River. The capacity
of the Noi River and its irrigation canals is estimated at 10 percent (350 m3/s) of that of the
Chao Phraya River (3,500 m3/s) due to the four regulators for irrigation purpose, but some
flood management plans calculates the possibility of a higher intake until 500 m3/s with
controlled flooding. An irrigation canal splits of on its east bank running more or less along the
Noi River bank until Huai Chan in Inburi district of Sing Buri province.
The Chana Sut water regulator (4 water gates) is the second barrier in Choeng Klat and
controls the water level of the first stretch. The regulators allow the water level to be raised in
that area from which canals branches off and deliver water to areas deprived of a natural flood
regime. At this regulator an irrigation canal branches of on the east bank running southwest. 
|(The Chana Sut Water Regulator)
|(The Phak Hai Water Regulator)
|(The kilns at Choeng Klat)
|(Wat Maha That at San Buri)
|(The Boromma That Water Regulator)
|(The Yang Mani Water Regulator)
Van der Heide proposed many projects, but failed to receive the necessary attention from the government
and resigned in 1909. It would be only in the late 1940s, that the Chao Phraya Barrage Project (Chai Nat
Dam) was reviewed and appraised, and found suitable for international financing. The Chao Phraya
Diversion Barrage was constructed to divert water to irrigation canals and natural channels both on the left
and right banks of the Chao Phraya River which covers most of the irrigable area in the lower part of the
delta. The Noi and the Suphan Rivers were excavated and enlarged to serve as supply channels for the
downstream irrigation areas on the right bank. 
Suphat Vongvisessomjai wrote that a study of the Food and Agriculture Organization (FAO) in 1948
concluded that Thailand’s economic strength lay in exporting high yielding rice 2-3 times/year to alleviate
world-wide food shortages caused by the Second World War. After having secured a loan from the
International Bank for Reconstruction and Development (IBRD) in 1952, Thailand started the Greater
Chao Phraya Irrigation Project in the Chao Phraya delta a year later. In 1957, at the finalization of the first
phase (Chai Nat dam, renamed later Chao Phraya Dam) the entire work was recognized as Asia’s largest
irrigation project. The Bhumibol Dam became operational in 1964 and the 25-year irrigation enhancement
program was finally finished in 1977 with the inauguration of the Sirikit Dam. 
The Chao Phraya Dam was constructed to divert water into irrigation canals and natural channels both on
the east and west banks of the Chao Phraya River. The project was designed for supplementing irrigation
to increase the rice production both for domestic consumption as for export.
The Noi River in this project was to convey water to a defined irrigated area of the upper delta and in
addition channel water to the lower delta. For this reason the Noi River was dredged and enlarged.
Numerous newly human-engineered channels interconnected the natural rivers, initially used for transport,
and now basically for irrigation. The Noi River received four water regulators in the irrigation project in
order to raise water level and divert water into the irrigation field: at the mouth in Boromma That, at Chana
Sut, Yang Mani and Phak Hai. From these regulators other canals split of to irrigate areas east and west of
the Noi River. Each of these water regulators was equipped with a water barrier (3 or 4 water gates) and
a navigation lock. The function of this regulators are multiple: raise the water level up to higher lands which
in some areas are lacking a proper irrigation system, regulate the water level in flooded areas, in particular
by preventing higher water levels in downstream areas to backlash them and help to store water in the
drains for later use in the dry season. 
The Yang Mani water regulator (4 gates) is the third barrier and controls the second
stretch. From here a canals splits off from the west bank along Road #3454 and follows more
or less the river until Bang Jak where it continues south. On the east there is a canal in
connection with the Chao Phraya River.
The fourth and last barrier on the Noi River is the Phak Hai water regulator (3 gates)
controlling the third stretch of the river and diverts water to the Phak Hai project. The Phak
Hai - Chao Chet canal starts on the west bank running parallel with the river until Sena where
it splits east, returning to the Noi River via the Sena water regulator and west, continuing
towards the Bang Yeehon canal for irrigation purposes.
The upper delta west bank project finally was perceived rather complex and very difficult to
operate and manage efficiently.
Along the Noi River, a key transportation route in the Ayutthayan Era, the pottery industry
flourished contemporary with the ceramic production industry in Sukhothai Province.
Discoveries of Noi pottery at numerous shipwreck sites in the Gulf of Thailand are witness of
a ceramic production clearly meant for export. The kilns were established along the Noi River
and the excavated sites indicate that the pottery industry along the Noi was very important
during the Ayutthaya Period.
Maenam Noi pottery is mainly composed of various types of jars, bottles, vases, mortars,
water pipes and architectural ornaments, both unglazed and blackish - brown glazed. A
characteristic of the storage jars for example was that the jars had four thick horizontal loop
handles. The jars, called "Hai Si Hu" were mainly exported as containers for honey, oil, eggs
or food for sale, or to contain provisions during a journey. A large quantity of storage jars of
the Noi River kiln site were found at wreck-sites in several parts of the world as well as in
almost all the wrecks in the Gulf of Siam, in Malaysian and Indonesian waters. The famous
four-lug jars were also found in maritime communities in Africa, at shipwreck sites in
Australian water and on-land sites in Japan. Other type and sizes of ovoid bottles, wide mouth
globular jars, large basins, water bowls, pear-shaped bottles with flared mouth (spirit bottle),
water jugs, mortars, stoves, architectural fittings and decorative items, floor tiles, roof tiles,
drainage pipes, cannon balls, figures of divinity, mythic animals and clay dolls for mystic
functions, were produced near the Noi.
An important Noi River Pottery Site was situated next to the Phra Prang Monastery in
Choeng Klat sub-district of Bang Rachan. The site was excavated for archaeological
study purposes during the years 1988-1989 under the Archaeological Research Section
from Division of Archaeology of the Fine Arts Department. On the site are the remains of
several large kilns dating back to the Ayutthaya period. It is believed to be the largest
earthenware production site of that period. With a shape somewhat resembling a roofed
boat, the kilns were made of brick, with ventilation stacks slanting upward. They once
produced a wide variety of utensils and building materials, including jars, bowls, mortars,
pots, gable tops and floor tiles.
The Mae Nam Noi ceramic manufacturing cluster was the largest among all ancient
ceramic kiln sites in central part of Thailand that flourished during the Ayutthaya Period
(14th - 18th century AD). Constructed brick kilns of the cross draft type lined the west
bank of the Chao Phraya Noi River in Choeng Klat sub-district. 
Starting from the Boromma That water regulator in Chai Nat, there are a lot of fish farms
along this track of the Noi River. The fish mainly farmed on this waterway is the red tilapia
known in Thailand as Pla Thapthim, scientific name "Oreochromis niloticus". The Tilapia is
very common in Thai cuisine and a type of fish that is very popular for fish farming worldwide.
The fish is raised in floating cages and fed about five times a day. This kind of fish farming
teases the subtle balance of nature, but also the owner’s wallet. An excess of fish cages in the
river could quickly overload its carrying capacity. The same, if too much fingerlings are
brought into the cages, there will be overcrowding when they grow. Fish breathe oxygen
dissolved in water and in the case of overcrowding, the fish has less oxygen to breath and
many will die of asphyxiation.
Overfeeding of the fingerlings is even worse. The commercial feed and chicken manure not
eaten by the fish sinks to the bottom and decomposes, consuming more of the oxygen
dissolved in the water. Oxygen for the fish reduces fast and when the oxygen is depleted, the
In March 2007 fish farmers pulled 100 tons of dead fish from Thailand’s Chao Praya River,
prompting authorities to launch an investigation into pollution of the country’s longest river. The
dead fish, worth about 30 million baht amount to the “biggest damage ever to the Chao Praya’
s fishing industry”. The cause was determined to be oxygen deprivation on a massive scale.
The Noi River next to the Chao Phraya River, also serves as a major source of food and
income for riverside communities and local markets across central Thailand.
We found a lot of water hyacinth (Eichhornia Crassipes), a weed originating from South-America, near the water regulators and in the river bends.
Sometimes the Noi River was so clogged up, that we had to take the kayaks out of the water, carry them and bring them back in again after having passed a
- two hundred meters long and half a meter high - densely intertwined green carpet, floating freely on the surface; impossibly to penetrate by any boat or
vessel; a serious hindrance to water transport.
Eichhornia Crassipes was introduced as an ornamental plant intentionally from Java, Indonesia in 1901.  Steve van Beek mentioned that it was brought in
by one of King Chulalongkorn’s consorts, who was struck by the beauty of its flowers, from Indonesia and put in garden ponds as a decorative.  From
the ponds the water hyacinth found its way into the canals and from there into the rivers. In a short time canals, rivers, and water reservoirs all over Siam
were clogged and extensively infested with water hyacinth. The Water Hyacinth Control Act was promulgated in 1913 in Siam in order to prevent further
spread of the plant but the Control Act was far from stopping the floating macrophyte.
In June 2011, water hyacinth was found blocking the water gates and sluices up to half a kilometer, making navigation on the Noi River impossible until Phak
Hai .“Phak Top Chawa” (plant wrested out of Java?) as it is called in Thailand, causes a variety of problems. The plant is a vigorous grower, can double its
surface within two weeks and can weigh up to 200 tons per acre. It clogs up irrigation intakes and water supply systems and can become so dense that it
forms a real herbal barrier, blocking waterways; as such a possible cause for flooding. The presence of this aquatic weed forms a micro-habitat and vector
for diseases, engendering major public health problems such as: malaria, schistosomiasis and lymphatic filariasis. 
The rate of water loss due to evapotranspiration nearly doubles in case the water surface is clogged with aquatic plants and has of course important
implications in zones where water is already scarce. There are indications that in hyacinth infested areas the water becomes warmer, reduces in oxygen and
causes fish to disappear, while reptiles such as snakes and monitor lizards become more prevalent. River bank habitants tend to throw their household
garbage and dead domestic animals into the river. The floating garbage and carrions intertwined with the stagnant water hyacinth carpets, release often a foul
smell of decomposition and could ultimately lead to local water quality deterioration. Still today, river water is used in many households for bathing, washing
cloths and dishes. Water hyacinth also reduces the biodiversity of the waterways by causing an imbalance in the aquatic micro-ecosystem; and as such
should have an effect on fish stocks and flora.
Water hyacinth can be used for the production of various things. In Bangladesh they make
paper and fiberboards from water hyacinth stems. In India and The Philippines water hyacinth
is dried and used to make baskets and matting for domestic use. Water hyacinth can be used
to aid the process of water purification either for drinking water or for liquid effluent from
sewage systems. The possibility of using water hyacinth as a substrate for biogas has been
under study for years. In Malaysia and other South-Asian countries fresh water hyacinth is
cooked with rice bran and fishmeal and mixed with copra meal as feed for pigs, ducks and
pond fish.  But all together, the programs to turn the weed into an economic asset were
mainly small-scaled and as thus rather unsuccessful. As Van Beek stated: “the initial investment
costs are too high and the price of the end product is low”.
Mechanical or manual extraction methods are used widely as a short-term solution but they are costly and not suitable for large weed infestations. Thailand
turned to biological control in the seventies. In 1977 and 1979 the mottled water hyacinth weevil, the Neochetina eichhorniae, a beetle insect, was introduced
as a biological pest control herbivore agent to control the spread of water hyacinth on Thailand’s waters. In 1997 and 1998 followed a sap-feeding mirid -
the Eccritotarsus catarinensis - that removes a considerable amount of chlorophyll from water hyacinth. In 1990 the chevroned water hyacinth weevil was
introduced, while the pyralid moth or water hyacinth moth – the Niphograpta albiguttalis - was released in 1994. Another moth - the Xubida Infusellus - was
released in 1997, all in an attempt to control water hyacinth. Today, water hyacinth still clogs up lakes, canals and rivers. Water hyacinth is difficult to
eradicate and requires permanently a coordinated management.
The Noi River was initially a stretch of the Chao Phraya River. In the Early Ayutthaya Period the river formed a natural defense border for the City state of
Ayutthaya. The river led to the southern frontier city of the Sukhothai Kingdom Phra Bang (Nakhon Sawan), dating from the Dvaravati period. Phra Bang
was a strategic point and at the same time an important trade center as it was situated on the confluence of the Nan and Ping Rivers forming the Chao Phraya
River. The Nan River led to Phitsanulok and Phichit and to Sukhothai and Phrae via its tributary the Yom River; while the Ping River led to Kamphaeng Phet
and Tak. It was called the northern water route. The City state of Ayutthaya was connect with the Chao Phraya River via a canal situated northwest of the
city called Khlong Maha Phram, a denomination which can be found on a map of the French Engineer de La Mare, drafted at the end of the 17th century.
The Chao Phraya ran at that time more than 10 Km to the west of the city.
The Noi - Chao Phraya Rivers run in between the Tha Chin - Mae Klong Rivers on its west and the Lopburi - Pa Sak Rivers to its east. Part of the present
Chao Phraya River between Chai Nat and Sing Buri must have been a tributary, splitting again into the Lopburi River, the main river surrounding Ayutthaya
until the 19th century. Those rivers formed a fertile delta in the Chao Phraya Basin suitable for human settlement. The Noi River bank was home to a number
of ancient settlements dating to the Dvaravati (6th -11th century) and Khmer (12th century) periods. Settlements developed along the river banks as water
was essential for agriculture, fishing and trade.
Sankha Buri, now in Chai Nat province and known as San Buri is an historical site located on the old Chao Phraya River, dating back to the Sukhothai
period. Prior the Ayutthaya period (1351 - 1767), the town was known as Phraek Sri Racha (Mueang Phraek) and built by King Lerthai, the fourth King of
Sukhothai (r.1257-1323) in 1317. The town was in the 15th century under Ayutthaya. Chao Yi Phraya, second son of King Intharacha (r.1409-1424) of
the Suphannaphum dynasty, was named ruler of this city by his father. San Buri was as thus a Muang Luk in the Early Ayutthaya Period. The town was likely
already occupied during the Dvaravati Period (6 - 11th Century) and followed by Khmer rule (12th century) thereafter, before becoming a frontier city of
Sukhothai. It was an important defensive post in both the Sukhothai and Ayutthaya Kingdoms.
Many of San Buri’s original historical sites were destroyed by modern farming, road
building and housing developments. Only a few traces remain in the compounds of Wat
Phra Maha That, Wat Phra Kaeo and locations in the vicinity. Remains are mostly from the
post-Dvaravati period, when the Khmer ruled Phraek Sri Ratcha. Remnants include
sections of the city wall and moat. Most of the stupas at San Buri were built by copying
those of other cities around central Thailand. The stupas at Sanburi could have been built
during the middle of the 14th to the beginning of the 15th century, when Sanburi shared a
close relationship with Suphan Buri and the two cities were related to the Lanna area. It is
believed to be the cities most prosperous period. During the Ayuttaya era, San Buri had
relationships with the Sukhothai dynasty, whilst the change from the U-Thong dynasty to the
Suphannaphum dynasty influenced the varied artistic styles of Lopburi and Suphan Buri.
The decline of Sukhothai caused San Buri to lose its role as frontier city and therefore its artistic and political significance. The gradual silting of the Chao
Phraya River, making the river narrow and shallow especially in the dry season, created problems for navigation and hampered trade and communication.
The new course, the main waters of the Chao Phraya River followed near Chai Nat, made that San Buri lost its prominence. The economic and
administrative activity shifted to Chai Nat. In the reign of King Mongkut (Rama IV) administrative reform took place and also the seat of the province moved
to Chai Nat, while the old town of San Buri became a district of the latter.
Also the city of Wiset Chai Chan, south of San Buri, a frontier outpost of the Ayutthaya Kingdom, was vacated when the Chao Phraya River silted and
changed its main course more east. The economic and administrative activity here shifted to the city of Ang Thong.
The Municipalities of San Buri and Wiset Chai Chan are mentioned in the Royal Chronicles of Ayutthaya. In 1584 Prince Naresuan and his brother
Ekathotsarot advanced from Lumphli, north of the City of Ayutthaya to Wiset Chai Chan with their royal barges to intercept the Burmese forces under the
governor of Bassein descending on Suphan Buri.  Prince Damrong wrote that Wiset Chai Chan was made a town when Somdet Phra Naresuan gained
victory over the forces of Hongsawadi, because it was the assembling place for Siamese forces from that time onwards .
On our kayak trip from from Chai Nat to Bang Sai we saw different fish capture methods.
Between Chai Nat and Pho Ngam there were mostly light bamboo bridge constructions on
which local people stands to sway a long-handled dip net. These bamboo constructions were
amply found all along the track until Pho Ngam.
Between Pho Ngam and Phak Hai locals used a kind of bamboo weir, mostly in V-form,
parallel with the bank and positioned with a narrow opening left against the current. At the
extremity of the opening a vertical slit trap is placed. This kind of fish trap is found very often
along the Noi River.
On the track from Sam Ngam to Phak Hai we encountered for the first time on the Noi River,
river bank operated stationary lift nets also called “Chinese fishing nets”, found abundantly
between Phai Cham Sin in Wiset Chai Chan district of Ang Thong province and Amarit sub-
district in Phak Hai district of Ayutthaya province. In some areas there was a large
concentration of such nets, presenting a beautiful view. These lift nets, which can be relatively
large, are operated from a small platform situated along the river bank. The installation consists
of a horizontal netting panel framed by bamboo or metal bars. After being submerged at the
required depth, the nets are lifted out of the water mechanically or by hand.
Other fishing techniques seen on the river was the use of cast nets, but more abundant
entangling nets, set up across the river. Entangling nets seen on the Noi River are mostly
strings of single netting walls, vertical, near by the surface in which the fish entangle. The nets
have floats on the head rope (mostly some small plastic bottles) and weights on the ground-
line or footrope. The gear is set anchored to the bottom or left drifting, free or connected with
the boat and hauled in by hand. Also hooks and lines were commonly seen.
Fishing is part of the life of the locals living on the river bank and at the rate fish is caught, the
river should be quickly depleted. Fortunately the temples along the river bank create often a
no-fishing zone called “khet Aphaiyathan” or “forgiveness area”, where the abbot asks the
commoners not to catch fish on or near the temple boundary along the bank. Fish as thus find
a safe haven near the temple and above all abundant food as temple visitors can feed the fish
and as thus accrue a bit of merit. Wat Khoi in Pho Rang Nok sub-district in Pho Thong
district of Ang Thong Province is such a place, known for its half century old fish sanctuary
called Wang Pla Wat Khoi (Fish Palace); an example which is followed by many temples
The Noi River is controlled by the four water regulators until Hua Wiang in Sena district. At Hua Wiang the river starts to take capacity as the Bang Luang
Canal, splitting off from the Chao Phraya River at Phong Phueng in Pa Mok district, pours untamed the waters from the Chao Phraya River into the Noi.
The river increases again its volume at the confluence with the Bang Ban Canal near Wat Sikuk in Nam Tao of Bang Ban district. The Bang Ban canal
delivers the waters from the Chao Phraya, flowed in near Ban Kum. Near Wat Sikuk the Noi River is at its widest, running further south a good pace, finally
to flow into the Chao Phraya River at Bang Sai, south of Ayutthaya.
From Sena onwards we find limited activity of tugboats and barges. The first shipyard building barges was found in Bang Nom Kho north of Sena and a
second wharf was situated south of Sena. There was also barge building at Bang Sai near the confluence with the Chao Phraya River.
The 170 Km kayak trip from Chai Nat to Bang Sai was undertaken in five days in the month of June 2011. My gratitude goes to Khun Tong Saengnark,
my kayak companion and guardian angel on this trip and Khun Dawit Yotphet, our obstacle handler always ready to intervene at the difficult spots.
 Chao Phya in Transition - Steve Van Beeck - page 11/12.
 King of the Waters: Homan van der Heide and the origin of modern irrigation in Siam - Han Ten Brummelhuis (2005).
 Chao Phraya Delta: Paddy Field Irrigation Area in Tidal Deposit - Suphat Vongvisessomjai.
 Water management and agricultural change: A case study in the upper Chao Phraya Delta - Francois Molle and Jesda Keawkulaya - South Asian
Studies Vol 36 No 1 June 1998.
 Text on the Noi pottery from the Chan Kasem Museum and on the Choeng Klat site.
 The Chao Phya in Transition - Steve Van Beek - page 168.
 Management of Invasive Alien Species in Thailand - http://www.agnet.org/library/eb/544/.
 Water hyacinth control and possible uses - http://practicalaction.org.
 The Royal Chronicles of Ayutthaya – Richard D. Cushman (2006) - page 99 / Source: British Museum, Reverend Phonnarat, Phra Cakkraphatdiphong
& Royal Autograph.
 Our Wars with the Burmese - Prince Damrong Rajanubhab (1917) - page 364.
|(Chinese fishing nets in Wiset Chai Chan)
|(Fishing on the Noi River)
|(Water hyacinth clogging up the river)