Efficient Mapping Of Intertidal Zone Topography Of Gujarat Coast Using Landsat Time Series Data

Intertidal zone, has the most diverse and ecologically significant marine habitat. Elevation Models from existing methods are limited by the tidal extent and conditions, and cannot be implemented over large areas. A robust and efficient methodology has been developed for speedy implementation of waterline method using multi-temporal Landsat datasets in cloud computing platform, to generate seamless DEM for intertidal zone of Gujarat. Automatic extraction of shorelines is carried out using NDWI mediancomposites and topography is extracted from highly accurate hydrodynamic model. Inter-tidal zone of $106.64 \mathrm{sq} . \mathrm{km}$ is mapped covering a tidal range of $0.28 \mathrm{~m}-8.8 \mathrm{~m}$. The derived product, a state-level seamless elevation model (30m spacing), is first of its kind for an Indian state. Detailed validations are carried out and overall accuracy of the model is measured as mode, mean, median of $0.34 \mathrm{~m}, 0.48 \mathrm{~m}, 0.46 \mathrm{~m}$ respectively with RMSE of 1.96 m, where 83.1% of the intertidal DEM falling within $\pm 2.5 \mathrm{~m}$ of reference DEM.