Tail End Aberrations of the Rivers of the East Coast of Central and Southern Tamil Nadu, India

The drainages have well defined life histories with youthful, mature and old stages. Such well carved out life histories and the related courses of the drainages are interfered and aberrated by the lithologies, tectonics, geomorphology and their processes. Along the coastal zones, the courses of the drainages are often disturbed and modified by the physical oceanographic processes. In this context, the tail end aberrations and the modified courses in the form of preferential migration, deflected drainages, eyed drainages, compressed meanders and other similar drainage anomalies were studied along the Tamil Nadu coast in some rivers using IRS LISS III FCC data. The studies revealed that the preferential northerly migration of Vaigai, Manimuttar and Pudukkottai Vellar rivers are due to E-W cymatogenic arching and the course of Tamirabharani is due to complementary E-W cymatogenic deep/graben. The preferential northerly migration of Cauvery river and Eruvadi rivers is due to active N-S northerly hinging faults. The S shaped drainages observed in some rivers are due to NE-SW sinistral faults, the Z shaped drainages do signify dextral faults. Thus, even such minor drainage aberrations confirm the post collision tectonics of the South India inferred by the earlier workers.