Abstract:

Lake shore areas in arid and semi-arid regions are critical hotspots for aeolian activity. However， traditional studies have primarily focused on aeolian processes on terrestrial surfaces， with comparatively limited research on wind and sand dynamics over ice-covered lake surfaces. The high-cold climate and strong wind regimes of the Qinghai-Xizang Plateau render ice-covered lake surfaces optimal for observing dust emission and deposition in winter， facilitating the monitoring and analysis of dust dynamics in arid environments. Following the 2011 outburst of Zonag Lake in the Hoh Xil region of the Qinghai-Xizang Plateau， extensive areas of lakebed in the western and southern sectors became prominent dust source areas. To monitor wind-driven sediment transport on the ice-covered lake surfaces post-freeze-up， this study utilized a time series of 11 remote sensing images covering Zonag Lake from October 2017 to June 2018. The Normalized Difference Sandy Land Index （NDSLI） was applied to extract spatial distribution data of wind-blown sediments on the lake ice. By applying specified thresholds to the NDSLI results， sediment-covered and non-sediment-covered areas were effectively distinguished. At the start of the monitoring period （November 24， 2017）， the dust-covered area was only 4.59 km²， representing just 2.97% of the lake surface. However， 79 days later （February 12， 2018）， the coverage expanded dramatically to 115.05 km²， covering 74.60% of the lake area. Furthermore， through finer threshold segmentation， this study was able to identify the spatiotemporal evolution patterns of varying sediment cover densities on the ice surface. Consequently， the NDSLI method demonstrates an effective approach for remote sensing monitoring of aeolian sediments on ice-covered lake surfaces， enriching our understanding of aeolian geomorphology and dynamics within cold， high-altitude arid environments.

Key words: Zonag Lake, lake ice, normalized difference sandy land index, aeolian sediment monitoring, Qinghai-Xizang Plateau