Feasibility of creating a fresh water reservoir in the Arabian Sea impounding the flood waters of Netravathi River

Abstract

This paper addresses the feasibility of creating a fresh water reservoir in the Arabian sea impounding the flood waters from Netravathi River. The project schemes comprises mainly two steps: first, the construction of the dyke in the Arabian Sea; and second, the process of natural replacement of salty water by rainwater and surface runoff to the reservoir. The study presents the detailed hydrological analysis of Netravati and Gurupura rivers including estimation of runoff into the sea. The study estimates the surface runoff at inlet and outlets of Netravati Basin along the costal lines of Arabian Sea. The existing land use along the costal lines of Netravati Basin is assessed. The dyke must be designed to separate fresh water from the salty waters of the Arabian Sea considering the tidal variations and wave heights. The bathymetric profiles of the sea bed has been created and presented in the paper. The annual runoff at the mouth of Netravati River was estimated as 388 TMC and just 2.5% of this would be sufficient to meet the present water shortfall of Bengaluru and Mangaluru. The annual sediment load was found to be negligible. The water quality parameters are well within permissible limits ensuring quality water from Netravathi to the proposed coastal reservoir.