KHLONG NAM YA 2 (คลองน้ำยา)
Khlong Nam Ya (Nam Ja) had its origin at the Takhian Canal (north and opposite of Wat Samphao Lom) and its mouth near Wat Pak Nam on the
present
Noi River. It was a canal connecting the old Lopburi River (encircling Ayutthaya) with the old bed of the Chao Phraya River, before the
latter was deviated in the mid-19th century towards
Hua Laem, the northwestern point of Ayutthaya's city island.

The old canal is largely silted and is known today as two stretches being
Lam Rang Prakan (Ban Prakan) and Khlong Ban Khlueng (Ban
Khlueng).

Khlong Nam Ya can be found on the maps of the French missionary de Courtaulin, the German ship's surgeon Engelbert Kaempfer (1651-1716) and
the Venetian map maker Vincenzo Coronelli (1650-1718).

In contradiction with Kaempfer's sketch, de Courtaulin indicated the origin of the canal adjacent and west of Khlong Takhian, which was later copied
in the same way by Coronelli. This depiction is tentative to position
Wat Khok Phlu, Wat Klang and Wat Nak along the west bank of Khlong Nam
Ya, as in fact these monasteries are rather far away from the banks of Khlong Takhian.

The mentioning "
66" within the Takhian Canal on Kaempfer's sketch and the explanation - R. magnus so auch nacher Ban kok gesehen (1) -
indicates that it was possible to travel to Bangkok via Khlong Nam Ya. Kaempfer's maps show that Khlong Nam Ya  split off from Khlong Takhian
and descended towards the old Chao Phraya River (the
Noi River today), running further south towards Bangkok. [1]

François Valentyn (1666-1727) in his work "
Oud en Nieuw Oost-Indiën" mentions Khlong Nam Ya, stating that the tributary was situated 2 or 3
Dutch miles north of Ban Sai:
Men ontmoet ter linkerhand z, en ter rechterhand een dorp, Ban Thraay genaamd, waar by een zeer fraei
gebouw des Konings legt. Hooger 2 a 3 mylen N. aan heeft men ter rechterhand een spruit, die in de Me-nam stort, en ter linkerhand weder
een dorp;
(2) [2]

Khlong Nam Ya can clearly be seen on a map named
"Sketch of The Menam & other Siamese Rivers from the Surveys & Observations of the
American Missionaries, Communicated by Mr. Consul Parkes 1855."
, published for the Journal of the Royal Geographical Society by J. Murray.
Albernarle Str. London 1856. The canal split off from the Takhian Canal as indicated by Kaempfer. Notice that on this map the Chao Phraya River
was not yet deviated towards the northwestern point of Ayutthaya's city island.

Footnotes:

(1) Translated: "Large river also goes towards Bangkok."
(2) In the 17th century the Dutch mile corresponded to 20,000 Amsterdam feet or 5662 meters.  The “
Amsterdam foot” was the standard
measurement for the VOC since 1650 and measured 0, 2831 meter. Today the mouth of Khlong Namya is situated 12.2 kilometers from the mouth
of the Noi River along the latter's east bank and fits thus the description of François Valentyn.

References:

[1] Engelbert Kaempfer. Werke 4. Engelbert Kaempfer in Siam. Edited by Barend Jan Terwiel. IUDICIUM Verlag GmbH Munchen 2003.
[2] Valentyn, François - Oud en Nieuw Oost-Indiën (1626) - Deel 3 - Boek 6 - Beschryvinge van Siam en onsen Handel aldaar.
Text &  maps by Tricky Vandenberg - March 2014