Abstract:
The rapid utilization of remote sensing satellites and techniques has provided a reliable,
effective, and near real time possibilities to characterize terrestrial ecosystem properties. Water
body extraction by using remote sensing has been the most significant method in the
investigation of water resources. Remote Sensing Satellite images can play a significant role in
investigation, dynamic, monitoring and planning of water resources. In this paper, a study has
been conducted to detect the changes in water body extent during the period of 2008 to 2017.
Bolgoda lake and river network were selected as the study area to monitor and analysis the
changes of the water body. Multiple methods including supervised classification (Support Vector
Machine (SVM)) and vegetation index method (Normalized Difference Water Index (NDWI),
Modified Normalized Difference Water Index (MNDWI), and Normalized Difference Vegetation
Index (NDVI)) are analyzed in order to maintain the accuracy and cross check of the outputs.
Landsat-5 Thematic Mapper (TM) imagery and Landsat-8 Operational Land Imager (OLI) have
high spatial, temporal and multispectral resolution and therefore provides reliable and accurate
data to detect vicissitudes in extent of water bodies. This study discovered an extensive
variation in water surface and vegetation of the Bolgoda area over a span of 09 years. It revealed
that 6.95% percentage of water area significantly degraded due to various causes around the
study area during past decade. As well as it also indicate 8.95% percentage decline of vegetation
in the area at the same time. In contrast, it also revealed that 28.81% percentage of built up
areas were expressively increased between the time periods. Rapid urbanization and
development of study area during the past decades has posed a serious threat to the presence of
ecological systems. There are identified numerous pressing problems in the Bolgoda area that
could lead to decline of the quantity and quality of the habitat, such as cleaning of vegetation,
specially mangrove areas for developmental activities, encroachment and illegal constructions ,
filling parts of wetlands for developmental activities , pollution from solid waste dumping,
industrial effluents, household sewage and so on.
