Decadal Evolution of Supraglacial Hydrology on the Nivlisen Ice Shelf: From Localized Ponding to Spatially Synchronized Hydrofracture Forcing (2015-2026)

Understanding the mechanical response of Antarctic ice shelves to surface meltwater is critical for evaluating their structural stability. This study presents 11 austral summer seasons (AS 2015-2016 to AS 2025-2026) assessment of supraglacial melt pond dynamics and their mechanical implications for the Nivlisen Ice Shelf grounding zone using Landsat-8/9 imagery combined with in-situ validation from the 44th Indian Scientific Expedition to Antarctica (ISEA-44). Supraglacial melt pond depths were retrieved from multispectral imagery and integrated into an Euler–Bernoulli flexural framework to estimate bending stresses, hydrostatic forcing, and the resulting stress intensity factors (Ktotal) across a network of ten major ponds. Two prominent hydrological events were identified: an extreme localized ponding episode in 2017 (maximum depth 6.92 m) and a spatially extensive meltwater event in January 2026 characterized by high thickness normalized energy (En = 97.81 MJ m⁻¹). Field validation using a Keller DCX-22 pressure transducer indicates that satellite retrievals underestimate pond depth by approximately 27.6% due to spatial averaging within 30 m pixels over concave pond bathymetry. Despite this conservative bias, calculated stress intensities reach up to 0.61 MPa m¹ᐟ², exceeding the commonly reported fracture toughness range for glacier ice (0.1-0.4 MPa m¹ᐟ²). These results suggest that episodic supraglacial melt ponding can generate stress conditions favorable for hydrofracture initiation in the Nivlisen grounding zone sector. The study demonstrates the value of combining long-term satellite observations with field validation to assess the evolving mechanical vulnerability of Antarctic ice shelves.