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

Abstract

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 17 concentrations using satellite reflectance can provide a new tool for environmental monitoring 18 of flood events in remote areas.

Declining greenness in Arctic-boreal lakes

“…The importance of substrates in controlling methane emissions has been confirmed in laboratory and field studies of northern-latitude lakes ( 109 , 111 ). As a result of this relationship, surface reflectance has even been used as a proxy for methane concentration in Siberian rivers ( 112 ). However, relationships to carbon dioxide fluxes are more complicated because of hydrologic loading of external CO 2 .…”

An extreme flood caused by a heavy snowfall over the Indigirka River basin in Northeastern Siberia

“…Satellite image analysis and mapping were conducted using ENVI 5.1 (ExilisVIS, CO USA) and ArcGIS 10.2 (Esri, CA USA) software. Water‐covered areas were determined from the normalized water indices (NDWI), which have been widely used for detecting open water features on land (McFeeters, ; Morozumi et al, in press), for an overlapped area of approximately 120,610 km 2 over the lower reach of the Indigirka River basin between July 11‐15, 2015 (four scenes) and July 11‐25, 2017 (six scenes) (Table ).…”

Photographic records of plant phenology and spring river flush timing in a river lowland ecosystem at the taiga–tundra boundary, northeastern Siberia

“…Here, we describe an archive of seasonal images taken by seven time‐lapse digital cameras, starting in 2013, of a river in the Indigirka lowland in Northeastern Siberia. At the Kodac site, or site “K” (70.56°N, 148.26°E), integrative studies have been conducted (Fan, Morozumi, Maximov, & Sugimoto, ; Iwahana et al, ; Liang et al, ; Morozumi, Shingubara, Murase, et al, ; Morozumi, Shingubara, Suzuki, et al, ; Shingubara et al, ; Tei, Sugimoto, Liang et al, ; Tei, Sugimoto, Yonenobu, et al, ). Information about some of the environmental factors at the study site are archived at the ADS database (https://ads.nipr.ac.jp/).…”

“…Information about some of the environmental factors at the study site are archived at the ADS database (https://ads.nipr.ac.jp/). The time-lapse camera images were previously examined to link the seasonal patterns of river water, plant physiological condition and river water chemistry (Fan et al, 2018;Morozumi, Shingubara, Murase, et al, 2019). Our dataset can provide unique information on quantitative phenological variables such as leaf opening, leaf falling and flowering and environmental variables including snowmelt timing and spring water flush timing of this river in eastern Siberia.…”