Abstract:
The evolution of ancient civilisations has been significantly influenced by their ability to
harness and manage water resources for agricultural and societal development. One
remarkable example of this is the sophisticated irrigation systems that emerged in various
regions around the world. Among these, the Yodha Eḷa (YE) Canal stands as an exemplary feat
of engineering and hydrological management. In Sri Lanka, there are several canals known as
YE in several parts of the country. Out of those, the most intrinsic canal is the one which
connects Kalāväva Tank to Tisāväva Tank in Anuradhapura, built by King Dhātusēna. The use
of gravity-driven flow, intricate single-side embankment systems, a very low gradient at some
places and some components known as diyakali and amuṇu gilma are the features that
demonstrate the profound understanding of hydrodynamics possessed by ancient Sri Lankan
engineers. Some researchers have explained the functions of certain components of the YE
based on certain principles. This article is an attempt to explain those functions from a
different perspective based on the concepts known as amuṇu gilma and diyakali with new
definitions. The new theory is mainly based on the understanding of the function of the
amuṇu gilma, mentioned in later chronicles such as Pūjāvaliya and Alakēśvara Yuddhaya. This
is supplemented by the folklore which confirms the existence of amuṇu gilma. With the
present research it is expected to confirm that the main objective of the construction of the
YE was to ensure the water security of the capital Anuradhapura and the amuṇu gilma was
the main component used by the ancient engineers to find the levels, control water flow and
ensure water securit
