Preprints
https://doi.org/10.5194/hess-2022-205
https://doi.org/10.5194/hess-2022-205
 
07 Jun 2022
07 Jun 2022
Status: a revised version of this preprint is currently under review for the journal HESS.

Climate sensitivity of the summer runoff of two glacierised Himalayan catchments with contrasting climate

Sourav Laha1,2, Argha Banerjee1, Ajit Singh2, Parmanand Sharma2, and Meloth Thamban2 Sourav Laha et al.
  • 1Earth and Climate Science, Indian Institute of Science Education and Research (IISER) Pune, Pune-411008, India
  • 2National Centre for Polar and Ocean Research (NCPOR), Ministry of Earth Sciences, Vasco-da-Gama, Goa-403804, India

Abstract. The future changes in runoff of Himalayan glacierised catchments will be determined by the local climate forcing and the climate sensitivity of the runoff. Here, we investigate the sensitivity of summer runoff to precipitation and temperature changes in winter-snow dominated Chandra (the western Himalaya) and summer-rain dominated upper Dudhkoshi (the eastern Himalaya) catchments. We analyse the interannual variability of summer runoff in these catchments during 1980–2018 using a semi-distributed glacio-hydrological model, which is calibrated with the available runoff and glacier mass balance observations. Our results indicate that despite the contrasting precipitation regimes, the catchments have a similar runoff response: The summer runoff from the glacierised parts of both the catchments is sensitive to temperature changes and is insensitive to precipitation changes; the summer runoff from the non-glacierised parts has an exactly opposite pattern of sensitivity for both the catchments. The precipitation-independent glacier contribution stabilises the catchment runoff against precipitation variability to some degree. The estimated sensitivities capture the characteristic ‘peak water’ in the long-term mean summer runoff, which is caused by the excess meltwater released by the shrinking ice reserve. As the glacier cover depletes, the summer runoff is expected to become more sensitive to precipitation forcing in these catchments. However, The net impact of the glacier loss on the catchment runoff may not be detectable, given the relatively large interannual runoff variability in these catchments.

Sourav Laha et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2022-205', Anonymous Referee #1, 16 Aug 2022
    • AC1: 'Reply on RC1', Argha Banerjee, 13 Sep 2022
    • AC3: 'Reply on RC1', Argha Banerjee, 13 Sep 2022
  • RC2: 'Review of hess-2022-205', Anonymous Referee #2, 16 Aug 2022
    • AC2: 'Reply on RC2', Argha Banerjee, 13 Sep 2022

Sourav Laha et al.

Sourav Laha et al.

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Short summary
A model study of two Himalayan catchments reveals that the summer runoff from the glacierised parts of the catchments responds strongly to temperature forcing and is insensitive to precipitation forcing. The runoff from the non-glacierised parts has an exactly opposite behaviour. The interannual variability and decadal changes of runoff under a warming climate is determined by the response of glaciers to temperature forcing, and that of off-glacier areas to precipitation perturbations.