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Abstract:
<!--!introduction!--><b></b><p>Due to limited in-situ observations, the glaciohydrological modelling is challenging in the Himalaya-Karakoram (HK) region. The present study reconstructs the runoffs in the Chandra-Bhaga basin, where a good amount of in-situ data is available. The SPHY (spatial processes in hydrology), a fully distributed high-resolution hydrological model, is applied over 1979-2020 using ERA5 reanalysis, Globcover land use and HiHydrosoil satellite products. The model is calibrated using 5 years (2010-2015) of in-situ catchment-wide runoff at the Chhota Shigri Glacier catchment outlet and validated with the available 6 years (2000-2006) of in-situ basin-wide runoff at the Chandra-Bhaga basin outlet. The modelled mean annual runoff for the Chandra-Bhaga basin is estimated as 57.79 ± 10.4 m3s-1 over 1979-2020. Maximum runoff occurs during summer-monsoon months, with a peak in July (132.74 ± 59.25 m3s-1). Glacier melt and snowmelt from the glacierized basin area, snowmelt from the non-glacierized basin area, rainfall-runoff and baseflow contribute 38%, 28%, 22% and 12%, respectively, to the total runoff at the basin outlet. The most sensitive model parameters are ‘<em>GlacF</em>’, which differentiates between the amount of glacier melt resulting in direct runoff and ‘<em>Tm</em>’, the threshold temperature for melting. The analysis also indicates that the hydrology of the Chandra-Bhaga basin is mainly dominated by summer precipitation. The study, using sufficient amount of in-situ data at the glacier catchment scale provides reliable reconstructed long-term runoffs for the basin.</p>
