Saini et al. (2026) Understanding glacier dynamics since the Little Ice Age in the sub-basins of Chandrabhaga Basin, Lahaul Himalaya, India

Identification

• Journal: Frontiers in Water
• Year: 2026
• Date: 2026-02-27
• Authors: Rakesh Saini, Ganga Sagar Bhagat, Mohd Ramiz, Sakshi Mankotia
• DOI: 10.3389/frwa.2026.1691398

Research Groups

• Department of Geography, Hemvati Nandan Bahuguna Garhwal University, Srinagar, India
• Department of General and Applied Geography, Doctor Harisingh Gour Vishwavidyalaya Sagar, Sagar, India
• Department of Geography, Jamia Millia Islamia, New Delhi, India

Short Summary

This study quantifies glacier changes in the Chandrabhaga Basin, Lahaul Himalaya, since the Little Ice Age (LIA) to 2023, revealing a 26.27% glacier area retreat and significant fragmentation, driven by regional warming and reduced precipitation, which also caused an upward shift in the Equilibrium Line Altitude (ELA).

Objective

• To quantify glacier loss from the Little Ice Age (LIA) to the present (2023) based on geomorphological mapping in the sub-basins of the Chandrabhaga basin, Lahaul Himalaya.
• To quantify climate trends based on available climatic records for the region.
• To understand the impact of climate change on glaciers in the study area.

Study Configuration

• Spatial Scale: Chandrabhaga River basin, Lahaul Himalaya, Himachal Pradesh, India (area of 5,907 km²). Includes four sub-basins: Chandra, Bhaga, Miyar, and Chandrabhaga Basin After Confluence (CBBAC). Elevation range from 2,200 meters to 6,500 meters above sea level.
• Temporal Scale: Glacier dynamics analyzed from the Little Ice Age (LIA) to 2023. Climate trends quantified for the period 1958–2024, with specific analysis for 1981–2024. Fieldwork conducted between 2022 and 2024.

Methodology and Data

• Models used:
  • Toe-to-Headwall Altitude Ratio (THAR) method for Equilibrium Line Altitude (ELA) reconstruction.
  • Mann–Kendal test for quantifying climate trends.
  • Sen’s slope estimator for measuring the magnitude of climate trends.
  • Monte Carlo random uncertainty method for error quantification in glacier mapping and temperature reconstructions.
• Data sources:
  • Little Ice Age (LIA) glacier extent: Inventory from Lee et al. (2021).
  • Contemporary glacier extent (2023): Landsat 8 Operational Land Imager/Thermal Infrared Sensors (OLI/TIRS) satellite images.
  • Elevation data: Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM) (30 meters spatial resolution).
  • High-resolution imagery for validation and detailed mapping: Google Earth Pro.
  • Climate data (monthly minimum temperature (Tmin), maximum temperature (Tmax), and precipitation from 1958 to 2024): TerraClimate gridded data (1/24°, approximately 4 kilometers spatial resolution).
  • Field validation: Hand-held Global Positioning System (GPS) unit (Garmin eTrex Touch 25) with 3.8 ± 1.2 meters horizontal accuracy.

Main Results

• Glacier Area Change: The total glacier area in the Chandrabhaga basin retreated from 1855.60 km² during the LIA to 1368.13 km² in 2023, representing a total loss of 487.47 km² (26.27%). The number of glaciers increased from 574 (LIA) to 1,011 (2023) due to fragmentation.
  • Sub-basin specific area loss: Bhaga (31.69%), CBBAC (26.87%), Chandra (24.66%), and Miyar (20.93%).
  • 48 glaciers lost more than 50% of their area, with 4 glaciers losing over 90% of their total area.
• Climate Trends (1958–2024):
  • Temperature: Annual average Tmin increased by approximately 0.031 °C/year. Winter Tmin increased by approximately 0.024 °C/year, and pre-monsoon Tmin by approximately 0.034 °C/year. Tmin warming intensified in recent decades (1981–2024), with winter Tmin rising by approximately 0.053 °C/year and pre-monsoon Tmin by approximately 0.067 °C/year. Annual Tmax increased by approximately 0.008 °C/year, with intensified rates during monsoon (approximately 0.049 °C/year) and post-monsoon (approximately 0.036 °C/year) in 1981–2024.
  • Precipitation: Winter precipitation decreased by approximately 1.4 mm/year, and pre-monsoon precipitation decreased by approximately 0.5 mm/year (intensifying to approximately 9.60 mm/year in 1981–2024, statistically significant at p < 0.05). Monsoon precipitation slightly increased by approximately 1.8 mm/year, while post-monsoon precipitation showed a negligible decrease of approximately 0.1 mm/year.
• Equilibrium Line Altitude (ELA) Change: The ELA showed an upward shift of 116 ± 35 meters (2.24%) from the LIA (5,162 meters) to 2023 (5,277 meters) across the basin.
  • Sub-basin ELA shifts: Miyar (144 ± 34 meters), Bhaga (121 ± 34 meters), Chandra (111 ± 34 meters), and CBBAC (87 ± 39 meters).
• LIA Temperature Anomaly: Reconstructed LIA temperature anomaly indicates a significant shift, with a mean temperature increase of 0.77 ± 0.24 °C since the LIA, ranging from 0.58 ± 0.26 °C (CBBAC) to 0.96 ± 0.23 °C (Miyar).

Contributions

• Quantifies the extent of glacier loss and fragmentation from the Little Ice Age to the present (2023) across the Chandrabhaga basin and its sub-basins, highlighting the spatial heterogeneity of these changes.
• Provides a holistic understanding of climate change impacts on glaciers in a transitional Himalayan climatic zone by integrating reconstructed LIA climate patterns with recent climate trends.
• Establishes a robust linkage between observed climate change (asymmetrical warming, particularly increased Tmin, and declining precipitation) and glacier retreat, supported by geomorphological mapping, satellite imagery, high-resolution climate datasets, and fieldwork.
• Offers insights into the implications of glacier retreat for regional hydrology and water resources, emphasizing potential impacts on drinking water, irrigation, and hydropower.

Funding

• Core Grant funding from ANRF (SERB), Reference: SERB/CRG/2021/004031.

Citation

@article{Saini2026Understanding,
  author = {Saini, Rakesh and Bhagat, Ganga  Sagar and Ramiz, Mohd and Mankotia, Sakshi},
  title = {Understanding glacier dynamics since the Little Ice Age in the sub-basins of Chandrabhaga Basin, Lahaul Himalaya, India},
  journal = {Frontiers in Water},
  year = {2026},
  doi = {10.3389/frwa.2026.1691398},
  url = {https://doi.org/10.3389/frwa.2026.1691398}
}