Revealing the river ice phenology on the Tibetan Plateau using Sentinel-2 and Landsat 8 overlapping orbit imagery

Abstract

River ice monitoring is vital for water resources, hydrological research, and operational management of flood risk from ice jams. Remote sensing offers an efficient way to monitor river ice. However, limited by the temporal and spatial resolutions of imagery, research regarding river ice phenology and processes on the Tibetan Plateau are lacking. This study provides an innovative monitoring approach to the river ice phenology on the Tibetan Plateau using imagery from the Sentinel-2 and Landsat 8 satellites in regions where the satellite orbits overlap during the cold season. We selected representative river reaches in different basins and climate zones in the overlapping orbit regions to reveal the river ice phenology and process on the Tibetan Plateau. The results showed that the overlapping orbit imagery significantly improved the temporal resolution of river ice monitoring, and detailed information on river ice phenology and processes could be obtained. The ice-cover durations in different river reaches on the Tibetan Plateau varied, ranging from 55 to 277 days. The ice-cover period tended to be longer in the river reaches with high latitudes and elevations. In addition, the river ice processes in reaches with flow cutoff were different from those in reaches with no flow cutoff. In winter, the ice period in cutoff flow river reaches was longer than that in non-cutoff flow river reaches. In a typical braided channel on the plateau, water usually froze in a small channel with low velocity, and the resulting ice gradually spreads to other small channels. This research is the first to investigate the river ice phenology and processes on the Tibetan Plateau, and the relevant results provide a reference for river ice studies on this plateau.