Detection of Extent of Sea Level Rise in a Coastal Lake System using IRS Satellite Imagery

Abstract

Coastal lakes are often under the threat of sea water ingress causing the depletion of fresh water bodies. Salinization due to sea water ingress causes impact on water resources especially in coastal areas. Thus there is scarcity of fresh water in this region. Climate change causes rise in sea level and this leads to increase of salinity in coastal lakes. Satellite imagery analysis now plays a prominent role in the quick assessment of water quality in a vast area. This study is an attempt to assess the extent of a lake system affected by sea water (Akkulam-Veli lake, Kerala, India) using Indian Remote Sensing Satellite, IRS P6 LISS III imagery. Field data were collected on the date of the satellite overpass. Simple regression equation using radiance in red band is found to yield superior results for the prediction of sodium content whereas polynomial equation using radiance of red band is found to yield superior results for the prediction of chloride content than the simple and multiple regression equations using spectral ratios and radiance from the individual bands from satellite imagery. The refractive index of water containing sodium chloride is more when compared with that of fresh water and this in turn results in high reflection of visible light in the red band when compared to blue and green bands. Hence the radiance of red band gives direct measure of sodium and chloride in lake water. IRS P6-LISS III imagery can be effectively used for the assessment of sea water affected area of the lake system.