Usability of water surface reflectance for the determination of riverine dissolved methane during extreme flooding in northeastern Siberia

• Published in: Polar Science
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: Flooding; Dissolved methane concentration; Arctic; Landsat 8; Indigirka; Polar Science; Siberia
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=15932; http://id.nii.ac.jp/1291/00015825/

An extreme flooding event occurred from June to July 2017 in the Indigirka River lowland of northeastern Siberia. We used Landsat 8 satellite surface reflectance data to detect the flood inundation area and extract water color for delineating different water sources. We also took direct samples of dissolved methane concentrations in the river water. Relatively high concentrations of dissolved methane (0.7–1.1 μmol l−1, or μM) were observed in four tributary areas in 2017 during the flood's recession, while the values remained low in the main channel (0.2–0.3 μM). In contrast, the concentrations of dissolved methane were low in both the main channel and tributaries during the non-flood period of 2016 (0.1–0.2 μM). We then used 2017 satellite reflectance data with an empirical model to estimate the spatial differences of dissolved methane concentration for water sources contributing to the methane-poor main channel and methane-rich tributaries and applied the results to the calculation of riverine methane in the study region (approx. 200 × 300 km). This approach to estimating dissolved methane concentrations using satellite reflectance can provide a new tool for environmental monitoring of flood events in remote areas.