Water Quality Assessment of a Lentic Water Body Using Remote Sensing: A Case Study

Abstract

Water Quality assessment of lakes, rivers, and reservoirs is a key issue for environmental monitoring and management. Lakes are subjected to sudden environmental changes caused by anthropogenic activities due to their multiple uses (agriculture, fishing, and boating, industrial and water supply). One of the most important issues in lake water management is water quality. Water quality assessments are being carried out using conventional methods which are very common and accurate, however, have the disadvantage of being expensive and labor-intensive. Further, sampling method and frequency are the major constraints to obtain representative samples. In order to overcome such hurdles in water quality management remote sensing approach has become more user-friendly and quite reliable. Remote sensing approach to water quality assessment is based on the optical bands in the region from blue to near infrared. These data are then used to explore the relation between the reflectance of water bodies and biophysical parameters such as: transparency, chlorophyll concentration (phytoplankton), and the organic and mineral suspended sediments. In the present study, an attempt has been made to understand the water quality characteristics of a lake situated in coastal, Kerala, known as Vembanad lake (a Ramsar site in south India) using Landsat-TM data. A relationship between Landsat-TM bands and suspended sediment concentration has been arrived at and compared with the field monitored data. It is noticed that TM bands such as TM5, TM6, and TM7 show higher correlation with observed data than bands 1, 2, and 3.