Mapping the Late-Holocene Glacial Geomorphology and Glacier Surface Types in the Mt. Harajoriha, Central Tian Shan

Abstract

Alpine glaciers in the central Tian Shan are an important indicator of climate change and also the freshwater tower for the transboundary countries in Central Asia. Knowledge about the glacier dynamics in the late Holocene, such as the Little Ice Age, and surface zones is still limited. In this study, two headwater basins, the Xiata and the Muzart basins, in the Harajoriha Mountain Range in northwestern China were selected to investigate the glacial landforms and glacier surface types using a combination of geomorphological mapping and remote sensing analysis. Several types of glacial landforms including glacial valleys, moraine complexes, moraine ridges, and trimlines were identified and manually digitized based on the 30 m Shuttle Radar Topography Mission (SRTM) digital elevation model, 10 m Sentinel-2 satellite imagery, and high-resolution images from Google Earth. In addition, an effective automated mapping algorithm was applied to the modern glaciers from a Landsat 8 scene using its optical and thermal bands to classify glacier facies, i.e. ice, snow, and slush zone, and supraglacial debris cover. Field trip to the forelands of the Aerqialeteer Glacier in the Xiata basin allowed detailed mapping of the proglacial environment and provided field checks for the mapping with GPS tracks and panoramic photos. Through this fused approach, the mapping results showed a combination of different sets of information connecting the glacier retreat since the late Holocene to contemporary glacier properties. They will be of particular value for future chronological reconstruction of past glacial events and for understanding how surface characteristics play a role in the heterogeneity of glacier responses to climate change.