Augmented normalized difference water index for improved monitoring of surface water

Environmental Modeling and Software
By: , and 

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Abstract

We present a comprehensive critical review of well-established satellite remote sensing water indices and offer a novel, robust Augmented Normalized Difference Water Index (ANDWI). ANDWI employs an expanded set of spectral bands, RGB, NIR, and SWIR1-2, to maximize the contrast between water and non-water pixels. Further, we implement a dynamic thresholding method, the Otsu algorithm, to enhance ANDWI's performance. Applied to a variety of environmental conditions, ANDWI with Otsu-thresholding offered the highest overall accuracy (accuracy = 0.98, F1 = 0.98, and Kappa = 0.96) compared to other indices (NDWI, MNDWI, AWEI, WI). We also propose a novel cloud filtering algorithm that substantially increases the number of useable images compared to the conventional cloud-free composites (124% increased observations in the studied area) and resolves inappropriate masking of water bodies and hot sands as clouds by conventional methods. Finally, we develop a Google Earth Engine App to readily delineate 16-day surface water bodies across the globe.

Publication type Article
Publication Subtype Journal Article
Title Augmented normalized difference water index for improved monitoring of surface water
Series title Environmental Modeling and Software
DOI 10.1016/j.envsoft.2021.105030
Volume 140
Year Published 2021
Language English
Publisher Elsevier
Contributing office(s) Western Geographic Science Center
Description 105030, 15 p.
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