• H S NEGI

Articles written in Journal of Earth System Science

• Susceptibility assessment of rainfall induced debris flow zones in Ladakh–Nubra region, Indian Himalaya

In recent past, rainfall-induced debris flow events in Ladakh–Nubra region have caused loss of lives and damages to civil infrastructures and army locations. Therefore, there is a need of high spatial and temporal monitoring of precipitation, and further to assess susceptible rainfall-induced debris flow zones in the area. We assessed the rainfall data collected at two gauge stations and observed a significant increase in the rainfall amount over the study region during summer-monsoonal period 1997–2017. Increasing trend was also observed from CRU gridded precipitation dataset. A GIS-based multi-criteria evaluation (MCE) method was performed by combining topographical, environmental and hydrological parameters for mapping of rainfall-induced susceptible zones. Suitability analysis of precipitation forecasts from WRF model at higher resolution (3 km) was also performed. A good agreement (r = 0.76) was observed between 4-day model forecast and field observed rainfall. Further, the simulated precipitation from WRF was incorporated into GIS model for assessment of debris flow susceptible zones for two cases of heavy precipitation events. The modelled high, medium, low and very low risk susceptible zones identified for the year 2015 events are validated with field survey and pre-post satellite imageries, and found in good agreement (ROC = 76.6%). The model was able to identify affected areas during the Leh cloud burst event in year 2010. In addition, a threshold value of rainfall for initiation of debris flow in the region was also reported.

• Long-term (${\sim}$40 years) mass balance appraisal and response of the Patsio glacier, in the Great Himalayan region towards climate change

Comprehensive assessment of the long-term mass balance (40 years) has been performed for Patsio glacier located in Bhaga river basin in the Great Himalayan region. The temperature-index approach has been employed for generating the time-series of annual specific mass balance of 25 years (1993–2018) using Snow and Avalanche Study Establishment (SASE) field observatory data in Patsio region. Results based on observational data showed nearly balanced condition until the year 1999 (+0.03 m.w.e/yr), followed by an accelerated rate of mass loss during the period 2000–2007 (−0.17 m.w.e./yr). This was evident due to the annual rise (+0.7$^{\circ}$C) in the temperature and drop (−122 mm) in the amount of precipitation during 2000–2007. A slight drop in the mass balance (−0.14 m.w.e/yr) was observed during the past decade (2008–2018) which was well supported by in-situ climate observations and published geodetic results in the region. The altitudinal distribution of modelled mass balance was observed well in correlation with the glaciological measurements for the periods 2010–2011 and 2011–2012. Further, seasonal sensitivity characteristic (SSC) was developed for the glacier illustrating the dependence of specific mass balance on monthly anomalies in temperature and precipitation. The developed SSC was used with bias-corrected temperature and precipitation estimates from recently released ERA5 reanalysis to reconstruct annual specific mass balance during since 1979s.

$\bf{Highlights}$

$\bullet$ Field based temperature lapse rate, precipitation gradient and snow melt factor established for the Patsio glacier.

$\bullet$ Seasonal sensitivity of the glacier mass balance was studied.

$\bullet$ Past reconstruction of the glacier mass balance using bias corrected ERA5 reanalysis.

$\bullet$ Comparison of modeled mass balance with published geodetic and glaciological results.

• Hydrological mass balance study of Siachen glacier, East Karakoram

The Himalayan cryosphere system is a major source of freshwater supply for the Indian subcontinent. The rivers originating from the Himalaya are strongly influenced by the behaviour of glaciers depending upon the regional climatic variables. Therefore, understanding the mass budget of glaciers is important. In the present study, we discuss the hydrological mass balance of the largest Siachen glacier in the Karakoram range. The computations of runoff and other parameters on such a large glacier are challenging due to data scarcity, difficult accessibility and complex topography of the region. The snowmelt runoff model (SRM) coupled with in-situ and remotely sensed information was used to simulate the glacier runoff for the past three decades (1986–2018). The accumulation in the form of snowfall and ablation in the form of snowmelt and evaporation were used as inputs for the estimation of hydrological mass balance. The SRM has well estimated the discharge of Siachen glacier with the coefficient of determination (R$^2$) 0.92 and average volume difference (D$_v$) 4.4% for the validation period. The study revealed that the Siachen glacier experienced few marginally mass gain episodes before 2000 but after that, a rapid and continuous mass loss has been observed. The average mass balance during the past three decades was found to be -0.11 ± 0.24 m w.e./year. This suggests that glaciers of East Karakoram have started losing mass; still, it is not as significant as generally observed in other parts of the Hindu Kush Himalaya.

• # Journal of Earth System Science

Volume 132, 2023
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019

Click here for Editorial Note on CAP Mode

© 2022-2023 Indian Academy of Sciences, Bengaluru.