The International Day of Action for Rivers on March 14 passed by without a murmur in Bangalore. A city that drew on two reservoirs of the Arkavathy for its water supply, now has no words left for the river that satiated a third of its water needs. Yet, plans to rejuvenate it cannot be implemented given the existing knowledge gaps on the issue, says Subir Ghosh. Contributed by : Sharachchandra Lele, Ashoka Trust for Research in Ecology and the Environment (ATREE)