Comparative Analysis of Blue Carbon Stock in Coastal Watersheds of Four Major Rivers

Global attention to blue carbon, which absorbs significant amounts of carbon, has increased as an alternative solution for reducing greenhouse gases, a major concern in the international community. However, as blue carbon is threatened by land cover changes and sea-level rise, preliminary studies on assessment and restoration have been conducted for efficient management. While domestic research has focused on field surveys of carbon absorption capacity and storage, studies establishing spatial information systems have been limited. Therefore, this study developed blue carbon spatial information for the coastal watersheds of the four major rivers. Total carbon storage within watersheds was calculated based on data from field surveys of 21 domestic tidal flats and various tidal flat spatial information datasets (global distribution of tidal flat ecosystems, Subdivision land cover map, 1/25,000 coastal data and 2018 tidal flat data). Watershed health indices were calculated based on total carbon storage. The carbon storage per unit area was highest in the Han River coastal watershed, followed by Nakdong, Geum, and Yeongsan River Coastal Watersheds. Among the various tidal flat spatial information datasets applied, analysis revealed that the highest carbon storage values were found in Han (7,321,321.72 Mg C, Nakdong (197,943.19 Mg C), Geum (469,228.90 Mg C), and Yeongsan (2,849,389.2 Mg C) River Coastal Watersheds. The health index analysis comparing various tidal flat spatial information datasets indicated peak values in Han (54.12), Nakdong (82.92), Geum (75.40), and Yeongsan (59.58) River Coastal Watersheds. The blue carbon spatial information developed in this study can potentially support policy decision-making and future research utilizing spatial information, such as analyzing factors affecting blue carbon absorption rates.