Delineation of Water Inundation Areas Using Landsat۸ Data in Gorgan Sub-Basin

The precise mapping of water inundation areas in terms of both spatial distributions and temporal variability is the basis for providing fundamental information on flood risk mitigation strategies and helps in efficient water resource management. High-precision remotely sensed data is frequently used for identification of water inundation areas in watershed scale. Different indices have been developed and implemented to identify the flooded areas. In this study, three indices of Normalized Difference Water Index - Modified Normalized Difference Water Index (NDWI-MNDWI), Automated Water Extraction Index (AWEI), and Water Index (WI) are calculated using the Landsat ۸ images in Google Earth Engine platform. The Validation results showed that the AWEI index with an accuracy and kappa coefficient equal to ۹۸% and ۹۶%, respectively is more efficient than the other indices in identifying water inundation areas in the study area. Moreover, the Pearson’s correlation coefficient between the time-series of water inundation areas identified by AWEI index and the corresponding daily discharge data recorded in Nomel Dam station (r= ۰.۵۹۳) indicates better performance of this index rather than WI and NDWI-MNDWI (i.e., r= ۰.۵۲۱ and ۰.۴۶۸). The indices adopted in this study could potentially use for the identification of water inundation areas, especially for the floods and precise-topography data scares regions.

Keywords:

Gorgan , Water inundation area , Remote Sensing , Landsat ۸ , Water Extraction Indices