Hydrological studies are very significant for the conservation and management of wetland ecosystem. Any alteration of hydrological characteristics of wetlands affects the abundance and diversity of biota. Thattekkad Bird Sanctuary showed difference in environmental conditions and hydrological parameters. Different hydrological parameters from eight ecological distinct areas were studied for three years. A significant difference was notices in two periods of wetland and changes taking places in the water chemistry of Thattekkad Bird Sanctuary wetland area. And this area were degraded due to habitat alteration.