Physical factors related to the marine disposal of industrial effluents off Pondicherry

Abstract

Field studies were carried out during February and April, 1981 to collect the environmental data on the physical characteristics of the coastal waters and the sea bottom off Pondicherry, required for the planning and design of marine outfalls for the effluents from two chemical factories. Tides and currents were recorded and the advective and diffusive behaviour of the surface waters was evaluated. The tidal oscillations were noted to be moderate along the Pondicherry coast and the currents were generally weak. The contribution of wind on the surface drift was considerable. The bathymetry of the area was supplemented by delineating the seabed sediment distribution. A silty/clayey belt between 8-m and 12-m contours was identified. Otherwise the nearshore bed was mostly composed of sand. Dye-diffusion studies showed that the waters off Pondicherry proper were less turbulent than those off Pilliarkuppam. The results are discussed in the context of locating effluent outlets