Assessment of impact of brackishwater aquaculture on Pulicat lake environment and its nearby resources using remote sensing and GIS techniques.

Abstract

Pulicat Lake is the second largest brackishwater lake in India and house for migrant water birds and breeding ground for several species of birds and marine organisms. Remote sensing, Geographical Information System (GIS) and Global Positioning System (GPS) were used to assess the changes in the land-use pattern in and around the Pulicat region. Digital image processing of the IRS 1C LISS-III images (2005) and Survey of India toposheets (1967) were used to derive the land-use pattern and classified images were analysed using GIS for detection of changes. The results indicated that the Pulicat lake water spread area and lake mud area have been reduced from 28758.63 ha to 26848.36 ha and 22841.67 ha to 21627.27 ha during 1967-2004 respectively. The development of aquaculture was estimated to be 382.77 ha along the lake channel and change detection analysis revealed that aquaculture farms were mostly converted from agricultural lands. The irrigation tanks have reduced by 2629.72 ha in between 1967-2005 and this was silent and unnoticed degradation which needs immediate attention and prompt action. Though the Pulicat Lake was in the limelight in view of anticipating aquacultural development, the lake was not affected due to aquaculture and this study revealed unambiguous visual information on the alarming levels of human-induced environmental degradation of tanks.