Mapping Oyster Reef Distribution Using Kompsat-2/3 and Linear Spectral Unmixing Algorithm - A Case Study at Hwangdo Tidal Flat

Abstract

Oyster areas are widely used as species of biological indicator, and they are also the most important shellfish in terms of ecosystem economic valuation. Oysters are production on the west coast before 2007 accounted for about 5 % of the nation's total production, but the 2007 Hebei Spirit oil spill caused production to plunge to less than 1 %. Therefore, spatial distribution maps of oyster reefs are required to help local authorities define management strategies. In this study, Kompsat-2/3 was used to map oyster reef distribution and analyze the distribution of oyster reefs based on linear spctral unmixing in Hwangdo tidal flat. A spectral library, collected in situ for various conditions with a field spectroradiometer, was used to conduct linear spectral unmixing classifications on Kompsat-2/3 data. The classification result shows very high accuracy, with an overall accuracy of 95 % or more, and there were misclassifications in some areas. The most causes of misclassification are the similarity of spectral characteristics and the limitations of the spatial and spectral resolutions of satellite images. For this reason, it was difficult to distinguish between oyster reefs and area distributed with many macrobenthos, and small-young oyster reefs were difficult to classify due to very weak reflectivity. In addition, the sand bar, it was is difficult to distinguish between oyster reefs related to dead reefs and sandbars because of the high reflectivity of these areas in the imagery. As a result of analyzing the change in the oyster reef area, it increased in 2019 compared to that in 2015. Especially, the oyster reef area increased in 30-50 % sand content and decreased in 20-30 % and 60-70 %. The changes of sand sediment seem to affect the distribution of oyster reefs. This study may be useful for mapping the distribution of oyster reefs and understanding the spatial variation of their habitat.