IRRIGATION SYSTEMS IN VIJAYNAGAR EMPIRE TIMES AND IRRIGATION STRUCTURES IN THE OLD MYSORE STATE

India and Iran have common bondage from times immemorial as irrigation systems in both the countries are age old. The Persian wheel to lift water is a technique that came to India from Iran during Mogul times. Like wise the Ghanat system of tapping water from the hill slope by underground tunnels is also a technique from Iran used in many places in India during the Mogul time. Both are in existence in various parts of India. The irrigation systems during Vijaynagar Empire in the 14th century in the form of tank systems as well as simple diversion structures across large rivers like Tungabhadra are working efficiently even today although their maintenance is being done poorly. The gauging devices to measure tank storage and apportioning for various purposes speak of the high degree of understanding of Hydraulics and Hydrology of the then engineers specializing in water management and who were named as Jalatantris. There are even today in existence treatises on water management in some of the old archives in the country. Like wise the Wadeyars who ruled the princely state of Mysore during the 15th century onwards built number of irrigation diversion works across Cauvery River in the South India and many structures are in existence even today working well. The Bangara Doddi Kaluve Aqueduct carrying a distributary across the river Cauvery is more than 4 centuries old in good working condition and probably the oldest aqueduct in service in the world. The paper describes the design and construction features of the irrigation systems of the Vijaynagar Empire as well as those of the Princely Mysore State with some detail along with lessons that could be learnt from these historical and physical evidences in the field of water resources engineering with illustrations. Along with these two instances from the history of irrigation development in India are two cases that taught the engineers of the world about the need for providing a surplusing arrangements during flood periods and the understanding of flood hydrology and also the instance of a dam built in the beginning of the 20th century that made the water resource engineers aware of the fact of uplift pressure in the base of solid gravity dams, leading to such new interventions as the inspection and drainage gallery to relive the uplift pressure which is a common feature in all the modern masonry and oncrete dams in the world. This led to a more safer technique in the design of gravity structures on rock foundations and is now a standard in all text books of dam engineering taught in the field of civil engineering.