Adaptive and Integrated Management of Wastewater and Storm Water Drainage in Kolkata — Case Study of a Mega City

Abstract

Situated between the tidal river Hugli on the west, the overflowing swamps on the east, and having tidal creeks surrounding, Kolkata suffered chronically from drainage congestion and water logging (Fig 1), especially during monsoon period with large run-off The city proper has a combined sewer disposal system laid in west to east direction as per natural slope of the basin. The drainage is disposed through channels and canals partly via wetland ecosystem with sewage-fed fisheries for natural sewage treatment and partly directly to river Kulti, which further carries the discharge to Bay of Bengal. The added areas lack proper central sewerage collection system by the municipality and sewage management is done by septic tank, surface drain, conduits laid underground and deposited to the canals and local ponds resulting in pollution and health hazards. Though works have been done by the Central and State Government Organizations, the results have not been totally satisfactory due to many factors on the face of tremendous force of unprecedented urbanization. Recently, increasing awareness about environment, pollution, health hazard and sustainability has generated some actions taken up for better drainage solution in an adaptive and integrated manner. The municipality and local government are introducing measures, which are anticipated to minimise the adverse impacts on environment.