The River Vennar originates from Grand Anicut across Cauvery River at
Km 27.26 below upper Barrage. It traverses through Thanjavur, Thiruvarur and
Nagapattinam District and empties in to Bay of Bengal by branching off into number of rivers m
It irrigates an extent of 4.96 Lakhs acres in the above three districts besides serving as drainage carrier. The Vennar at LS 55.270 Km at Thenperambur Village (V.V.R. Head)trifurcates as Vennar, Vettar and Vadavar
Vennar at LS 96.120 Km at
Needamangalam Village trifurcates as Vennar, Koraiyar and Pamaniar (Koraiyar Head) The main Vennar river again bifurcates as Vennar and Pandavayar at LS 108.730 Km. At LS 110.54Km Vennar again bifurcates into Vellaiyar and Vennar.
The \par
Pandavayar river finally infalls into Vellaiyar river. The Koraiyar river at LS 122.150 Km \par
branches as four river cum drainages namely Koraiyar, Ayyanar, Mulliyar and Harichandranathi. Mulliyar again bifurcates as Mulliyar and Adappar at LS 130.236 Km in Kottur Village. All these branch rivers namely Vellaiyar, Harichandranathi, Mulliyar,
Adappar and Koraiyar infalls into Bay of Bengal
Normally the floods generated from the catchment below Grand Anicut a vast area lying south of Grand Anicut Canal surrounded by Kulathur, Gandarvakkottai,Vallam, Sengipatti and Thiruverumbur spreading over four Taluks in two District, directly enter river Vennar after crossing Grand Anicut Canal causing drainage problem
