Impact of glacier changes and permafrost distribution on debris flows in Badswat and Shishkat catchments, Northern Pakistan

Abstract

Knowledge of glacier changes and associated hazards is of great importance for the safety of the population and infrastructure in the mountainous region of High Mountain Asia. In this study, we assessed the impact of variations in glacier velocity, glacier surface elevation change, meteorological variables, and permafrost distribution on debris flows in Badswat and Shishkat catchments. In Badswat catchment, a debris flow initiated from the former glacial moraine on 17 July 2018. In Shishkat catchment, debris flows usually occur during summer months when air temperatures are highest. We conducted in-depth analyses of long-term in situ meteorological data, field evidence, and satellite images. We applied feature and offset tracking techniques to highresolution optical and radar images from Landsat, Planet and Synthetic Aperture Radar during 2013-2019 to estimate glacier velocities. We used geodetic methods to estimate glacier surface elevation change. We analyzed the associations between debris flow occurrence, permafrost distribution, and the variations in the 0°C isotherm. Between 1995 and 2019, the increase in temperatures in July is statistically significant for most low-and high-elevation meteorological Electronic copy available at: https://ssrn.com/abstract=4204639 stations. In Badswat and Shishkat catchments, permafrost is distributed over most of the catchment area and in the debris flow source areas. In Badswat catchment, no significant variations in glacier velocity and elevation change were observed over the study period; however, all three glaciers showed slightly higher velocity toward the terminus during the debris flow events. The debris flow in Badswat catchment damaged infrastructure and blocked the Immit River. The lake created by the blockage of the river inundated 34 houses, a community hall, agricultural land, and other infrastructure such as roads and businesses. Glacier dynamics and seasonal changes in temperature in the permafrost zone could have contributed to debris flow initiation. Our results show that climate and cryosphere change pose significant threats to the population in the region. Monitoring climate and cryosphere change can contribute toward the improvement of disaster risk reduction and mitigation policies.

Rock glacier distribution and kinematics in Shigar and Shayok basins based on radar and optical remote sensing

“…The effects of global climate change may lead to the thawing of permafrost and alter rock glacier dynamics in the region. This, in turn, could influence slope stability, runoff patterns, and water quality, potentially contributing to periodic landslides, debris flows, floods and other associated hazards (Hassan et al, 2023;Schmid et al, 2015). Insitu measurements of permafrost have shown an increase in permafrost thawing and the propagation of permafrost lower limits to higher elevations in the Tien Shan Mountains (Liu et al, 2015).…”

“…in the Hunza Basin (Hassan et al, 2021). Given the distribution of rock glaciers in the region, the destabilisation of rock glaciers and the creeping slopes within permafrost zones pose a hazard to infrastructure (Hassan et al, 2021(Hassan et al, , 2023Kääb, 2008)…”