Author(s): G. N. Paranavithana; J. M. W. S. Jayasundara; H. W. G. Harindra; W. D. N. Ranasinghe; R. S. Ranasinghe
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Keywords: Ancient irrigation systems; Sluice; Physical model; Sinhalese
Abstract: The growth of the Sri Lankan hydraulic civilization developed new techniques in water management systems such as reservoirs, and irrigation canals. -They are considered as advanced irrigation systems that have survived throughout history. Basically, reservoirs were built to keep the water table up by storing water by clay embankments across valleys. This water has been conveyed as irrigation water, creating a life cycle existed for so many centuries. The sluice and sluice gate is -two of the most important components in a reservoir and these components are the control devices of a reservoir. Control devices save the reservoir bund without damaging it by the velocity and pressure created on outflow of water. The ingenuity of the Sinhala irrigation engineers is best exemplified by the invention of the Bisokotuwa (which literally means queen - enclosure), later termed by Parker in 1909 Bisokotuwa, the enclosure where the water level lowers. As stated by parker in “Ancient Ceylon (1909)”, there is a special arrangement before Bisokotuwa which is called inlet barrel extended towards the middle of the irrigation tank and some of these barrels extended more than 100fts and spectacularly “Nuwara wewa” ancient sluice barrel extended up to 147fts which was constructed in 1st century B.C. Therefore, there must be an unrevealed hydraulic mystery about this kind of sluice barrel in some reservoirs in ancient Anuradhapura and Polonnaruwa era since our ancient engineers may not misspend their time and labor in vain for such kind of construction. To investigate the performance of inlet sluice barrel, physical model testing -is done based on the measured roughness values of ancient sluice structures made out of granite. The hydraulics of this ancient mechanism is revealed in this research.
Year: 2020