Sabyasachi Maiti

Shoreline changes in response to sea level rise along Digha Coast, Eastern India: an analytical approach of remote sensing, GIS and statistical techniques

Shoreline is one of the rapidly changing linear features of the coastal zone which is dynamic in nature. The issue of shoreline changes due to sea level rise over the next century has increasingly become a major social, economic and environmental concern to a large number of countries along the coast, where it poses a serious problem to the environment and human settlements. As a consequence, some coastal scientists have advocated analyzing and predicting coastal changes on a more local scale. The present study demonstrates the potential of remote sensing, geospatial and statistical techniques for monitoring the shoreline changes and sea level rise along Digha coast, the eastern India. In the present study, multi-resolution and multi temporal satellite images of Landsat have been utilized to demarcate shoreline positions during 1972, 1980, 1990, 2000, and 2010. The statistical techniques, linear regression, end-point rate and regression coefficient (R2) have been used to find out the shoreline change rates and sea level change during the periods of 1972–2010. Monthly and annual mean sea level data for three nearby station viz., Haldia, Paradip and Gangra from 1972 to 2006 have been used to this study. Finally, an attempt has been made to find out interactive relationship between the sea level rise and shoreline change of the study area. The results of the present study show that combined use of satellite imagery, sea level data and statistical methods can be a reliable method in correlating shoreline changes with sea level rise.

A three-unit-based approach in coastal-change studies using Landsat images

An understanding of a dynamic coast requires long-term investigation of changes taking place along its shoreline. Multi-date satellite images can be used to highlight long-term coastal behaviour. In the present study, a new methodology has been suggested, by proposing initial selection of three basic coastal units, namely, ‘land’, ‘wetland’ and ‘water’. These three coastal units have been used for identification of five different ‘change units’, namely, ‘land replaced by water’, ‘land replaced by wetland’, ‘wetland replaced by water’, ‘land accretion’ and ‘wetland accretion’. Based on this proposed approach, a case study has been carried out along the coastal area covering parts of West Bengal and Orissa states of eastern India using Landsat images. The derived coastal changes demarcated using satellite images have been verified by field checks. Further, these changes have been used to study three important coastal issues: sediment budget, coastal morphodynamics and hazard-zonation mapping. This study shows that consideration of three basic coastal units is an appropriate choice for studying long-term coastal changes using multi-date satellite data.

Identification and mapping of high-potential iron ore alteration zone across Joda, Odisha using ASTER and EO-1 hyperion data

ABSTRACT Identification and mapping of high-potential Iron Ore indicative alteration zone is important for new prospects. Here we have performed same through ASTER and Hyperion data by considering the in-situ and reported spectral signatures and Band Ratio techniques. The Minimum Noise Fraction and Pixel Purity Index have been applied for the noise reduction and pure pixel extraction from the Hyperion data. Spectral Angle Mapper algorithm has been used to identify the Hematite and Goethite exposures based on the spectral assembling. On the other hand, Ferric Iron, Ferrous Iron, Ferrous Silicates, and Ferric Oxide index have been applied on ASTER VNIR and SWIR data for demarcating alteration zones indicating subsurface occurrence of iron ore. Thereafter, the consistency index has been established between the ground truth/field observations and classified alteration through kappa statistics demonstrates the accurate identification and remote mapping of Iron Ore alteration zone in and around Joda region.

Appraisal of long-term shoreline oscillations from a part of coastal zones of Sundarban delta, Eastern India: a study based on geospatial technology

This study aims to analyze the long-term shoreline oscillations and its impact on coastal environment from a part of coastal zone of Sundarban delta over the last four decades. The present study was executed using four multi-temporal Landsat images during different dates. Automatic shoreline extraction model was developed in ERDAS Imagine software to identify the shorelines from satellite images. Digital shoreline analysis system was employed for estimation of shoreline change rate. Shoreline change analysis (erosion and accretion) study has been carried out by developing a model in ArcGIS model development tool. Transect wise shoreline change study revealed that about two third of the total transects exhibits erosion and about one third of the total transects exhibits accretion. The results of average shoreline change rate during different periods show the negative change. This study provides substantial information on the nature of shoreline changes which would assist in proper planning and management.