Monitoring Ecological Conditions of a Coastal Lagoon using IRS Data: A Case Study in Chilka, East Coast of India

The Chilka Lagoon (N 19(0) 28' - 19(0) 54; E 85(0) 06' - 85(0) 35'), on the east coast of India in the Orissa State is the largest lagoonal system in the subcontinent and one of the largest tropical lagoons of the world. It is undergoing rapid transformation, which has severe implications for human settlement in and around the lagoon and the socio-economic condition of the state. Monitoring of these transformations has been undertaken through satellite remote sensing techniques as well as field observations in order to develop spectral signatures for coastal lagoonal features such as water types, turbidity and vegetation types. IRS 1B LISS - 1 digital data on 07-12-93, 11-10.94, 29-01-95, 27-04-95, 10-07-96 and 23-05-98 have been used. Digital image analysis has been carried out using the IBM RS 6000 Image Analysis System having V6.1 EASI/PACE software. Maximum likelihood classification has been used to classify the lagoon where ground truth observations have been integrated with the remote sensing data. The lagoon has been classified into different classes varying from a minimum of 9 categories during January 1995 to a maximum of 15 classes during July 1996. The time rate of change of different classes has been studied by estimating their area, which suggests that the vegetation growth in the lagoon is alarming. Algorithms have also been applied for developing different lagoonal indices which act as indicators of ecological changes. Two equations, predicting depth and total suspended solid concentration, have been validated with observed data.