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Exploring the links between variations in snow cover area and climatic variables in a Himalayan catchment using earth observations and CMIP6 climate change scenarios

Singh, D, Zhu, Y, Liu, S, Srivastava, PK, Dharpure, JK, Chatterjee, D, Sahu, R and Gagnon, AS (2022) Exploring the links between variations in snow cover area and climatic variables in a Himalayan catchment using earth observations and CMIP6 climate change scenarios. Journal of Hydrology, 608. ISSN 0022-1694

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Abstract

Changes in the spatial extent of the Snow Cover Area (SCA) of the Bhagirathi River Basin (BRB) in recent decades have impacted the hydrology of the region and the water resources of communities located downstream. Previous studies focusing on the region have to date been limited to the effects of terrain variables, namely elevation, slope and aspect, on variations in the spatial extent of snow cover without accounting for the impact of climate change. This study first investigates temporal changes in SCA in the BRB during the period 2001-2019, and their linkages to climate variability, and then examines how future climate change could impact the SCA of the basin and its implications for water resources. The SCA and Terrestrial Water Storage Anomaly (TWSA) over the basin were calculated using the MODIS daily snow cover and GRACE/GRACE-FO products, respectively, while estimates of temperature and precipitation were obtained from satellite observations and a reanalysis dataset. Climate change projections, for their part, were obtained from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and were downscaled to the catchment scale. A trend analysis revealed an increase in the SCA of the study catchment at both the annual and seasonal scales during the period 2001-2019, correlating with an increase in precipitation over the same time period. The results of trend analysis of TWSA in the basin also corroborated the increase in the mean annual SCA. A correlation analysis also detected statistically significant positive correlation between the seasonal (post-monsoon (r = 0.49, p<0.05) and winter (r = 0.54, p<0.05) SCA and precipitation, while a negative correlation was identified between SCA and both Tmax and Tmin during the post-monsoon (r = -0.53, p < 0.05 and r = -0.38, p > 0.05, respectively) and winter (r = -0.69, p < 0.05 and r = -0.10, p > 0.05, respectively) seasons. An analysis of climate change scenarios downscaled over the study region revealed a significant increase in Tmean, Tmax, Tmin and precipitation with respect to the base period (2001-2020) during the pre-monsoon and winter seasons in the 2030s under the SSP245 and SSP585 greenhouse gas emission scenarios. The Multiple Linear Regression (MLR) model established based on SCA relationships with temperature and precipitation predicted a reduction in the SCA of higher altitude zones (4000m and above) during the pre-monsoon, post-monsoon and winter under SSP585 and SSP245, thereby resulting in a decline in the Bhagirathi river flow, despite a projected increase in precipitation for the region. The study demonstrates the impact of projected changes in climate on the SCA of a Himalayan catchment, and the potential implications for regions where snowmelt is important to streamflow regimes.

Item Type: Article
Uncontrolled Keywords: Bhagirathi River Basin; CHIRPS; CMIP6; climate change; MODIS; snow cover area
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Divisions: Biological & Environmental Sciences (new Sep 19)
Publisher: Elsevier
Date Deposited: 23 Feb 2022 12:42
Last Modified: 11 Mar 2022 13:00
DOI or Identification number: 10.1016/j.jhydrol.2022.127648
URI: https://researchonline.ljmu.ac.uk/id/eprint/16393

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