Abstract:
Unplanned development led to uncontrolled urbanisation and spatial transformation of settlements in informal manner which have negative impacts on water bodies and the surrounding environment. The wetlands in India are under high threat due to increased human pressure. The 80 percent of lakes and marshes in India already been degraded or lost in past five decades. As per the Wildlife Institute of India’s report, wetlands in India are being lost at a rate of between two to three percentages per annum. The Pallikaranai marshland is located in Chennai and has been identified as one of the wetlands under National Wetland Conservation and Management Programme, GoI in 1985. This marshland is important for the city because it is rich in biodiversity and it act as a flood buffer zone for the entire city. The temporal land use and land cover (LULC) change analysis of marshland over the last five decades has shown that, from 5000 ha (1975), the marsh land area has reduced to <500ha (2018) due to encroachment on the marshland which resulted in reduction of water holding capacity from 55.78 million m3 (1975) to 5 million m3 (2018), with increased occurrence of flood events in the surrounding wards. The areas of marshland were heavily affected during Chennai flood 2015. The “Wetland Conservation and Management Rules, 2017 also says that dumping of waste and discharge of effluent or sewage is prohibited in wetland of India”. But in Pallikaranai Marshland, the lack of sewerage network in the surrounding settlements illegally discharge the sewage from households to the nearby ponds. The raw sewage from 31 tanks are entering the marshland, thereby affecting the marshland ecosystem adversely. And the Perungudi dump yard is located within the marshland, which poses the greatest threat to the sustenance of flora and fauna of the marshland and it also degrades the surface, ground and ambient air qualities. The WQI, HPI and LPI results shows that presence of heavy metals in surface and ground water resources because of the leachate from the dump yard. Due to this the ground water is highly contaminated within 2 km radius from the dump yard. Due to deteriorated water and air quality, people living within a radius of <1.5 km from the dump yard have complained about respiratory ailments. To mitigate these problems the implementation of environment management strategies in marshland ecosystem plays a vital role in protection, conversation and restoration of degraded marsh.
