Modelling Permafrost Distribution in Western Himalaya Using Remote Sensing and Field Observations

Abstract

The presence and extent of permafrost in the Himalaya, which is a vital component of the cryosphere, remains severely under-researched with its future climatic-driven trajectory only partly understood and the future consequences on high-altitude ecosystem tentatively sketched out. Previous studies and available permafrost maps for the Himalaya relied primarily upon the modelled meteorological inputs to further model the likelihood of permafrost. Here, as a maiden attempt, we have quantified the distribution of permafrost at 30 m grid-resolution in the Western Himalaya using observations from multisource satellite datasets for estimating input parameters, namely temperature, potential incoming solar radiation (PISR), slope, aspect and land use, and cover. The results have been compared to previous studies and have been validated through field investigations and geomorphological proxies associated with permafrost presence. A large part of the study area is barren land (~69%) due to its extremely resistive climate condition with ~62% of the total area having a mean annual air temperature of (MAAT) <1 °C. There is a high inter-annual variability indicated by varying standard deviation (1–3 °C) associated with MAAT with low standard deviation in southern part of the study area indicating low variations in areas with high temperatures and vice-versa. The majority of the study area is northerly (~36%) and southerly (~38%) oriented, receiving PISR between 1 and 2.5 MW/m2. The analysis of permafrost distribution using biennial mean air temperature (BMAT) for 2002-04 to 2018-20 suggests that the ~25% of the total study area has continuous permafrost, ~35% has discontinuous permafrost, ~1.5% has sporadic permafrost, and ~39% has no permafrost presence. The temporal analysis of permafrost distribution indicates a significant decrease in the permafrost cover in general and discontinuous permafrost in particular, from 2002-04 to 2018-20, with a loss of around 3% for the total area (~8340.48 km2). The present study will serve as an analogue for future permafrost studies to help understand the permafrost dynamics associated with the effects of the recent abrupt rise in temperature and change in precipitation pattern in the region.

Biennial analysis of probable permafrost distribution for Kullu district, North‐west Himalaya using Landsat 8 satellite data

“…We compared our results with the previous research (Allen et al, 2016;Khan et al (2021) According to our results, in 2016, the probable permafrost covered 6.63% of Kullu district, while according to Allen et al (2016) and Khan et al (2021), the percentage area covered by permafrost is 9.56% and 47.92%, respectively (Figure 9a and Table 5). Similarly, in 2018, according to our map, 4.42% fell under permafrost, while Khan et al, (2021) mapped it to 47.34% area (Figure 9b). Our results are in better agreement with those of Allen et al (2016), but in contrast, Khan et al (2021) map overestimated the distribution of permafrost in the study area (Figure 9a).…”

“…There are various methods of mapping the probable permafrost distribution of a region but the most widely applied method is by utilising MAAT (Baral et al, 2020;Hoelzle & Haeberli, 1995;Khan et al, 2021) and MAGT (Ran et al, 2018). Different researchers have used dataset from coarse resolution (WorldClim and MODIS) (Allen et al, 2016;Baral et al, 2020;Khan et al, 2021) to higher resolution (ASTER and Landsat) (Batbaatar et al, 2020;Pradhan & Shukla, 2022a). Khan et al…”

“…Gruber (2012) developed a global Permafrost Zonation Index (PZI) at a resolution of 1 km based on an empirical relation between permafrost and MAAT, which may be regarded as a first-order estimate of permafrost distribution. To predict permafrost distribution in the Western Himalayan area, Khan et al (2021) used MAAT, potential incoming solar radiation (PISR), and slope aspect as the primary factors. Allen et al (2016) produced a permafrost distribution map of Kullu district, North-west Himalaya, by calculating the mean annual ground temperature (MAGT) at the top of the permafrost based on MAAT.…”

Rock glacier Oasis: An alternative for agro‐pastoralism in a changing environment in the Himalayan cold desert

“…The biennial surface temperature of the rock glacier ranges from −5°C at upper altitude to more than 1.64°C in lower altitudes. The result of the recent permafrost model for western Himalaya (Khan et al, 2021) revealed that the rock glacier originates from a ‘discontinuous’ or ‘permafrost likely zone’ through ‘sporadic permafrost’ and flows down to a ‘no permafrost zone’. This reflects the fact that rock glaciers, with sufficient sediment input, can move far downslope such that their terminus position can be located at elevations where permafrost would otherwise not exist.…”

Perception of climate change from the Himalayan ‘cold desert’ Ladakh, India

“…This warming has been attributed to a progressive increase in the atmospheric concentration of greenhouse gases (anthropogenic factors) since the mid of the 20 th Century (IPCC, 2014, Allen et al, 2019. The rapid climate change is expected to have a significant impact on the freshwater resources, biodiversity, ecosystems and human well-being in the Himalayas (Myers et al, 2000;Khan et al, 2021). The Himalayan region is crucial as it replenishes and maintains the water budget of the major rivers originating from the entire 'third pole area' and catering almost 20% of the world's population.…”