Work Package 5 - Impacts on water resources: application of a distributed physically based hydro-glaciological model to studied basins to evaluate the influence of climate and glacier changes on the sustainability of the hydrological budget (Resp: M. Esteves and D. Koirala).
River discharges are continuously measured since 2010 at two hydromeric stations (Pheriche, Phakding) in the upper Dudh Koshi catchment (Figure 1). To control the rating curves, discharges will be regularly measured in the field, using an environmentally neutral tracer (dilution method), into the streams. To provide the best meteorological forcing for hydrological modelling, advantage will be taken from in-situ meteorological and glacier data collected by WP1 and the climate data produced by WP4 at high spatial resolution.
The main model to be used in WP5 is DHSVM-GDM, a spatially distributed physically based hydrological model already applied in the Everest area23. N. Champollion, a young researcher hired in CNRS in 2020 and specialist of the Open Global Glacier Model OGGM (https://oggm.org/), will complement and validate the results of DHSVM-GDM regarding the evolution of glaciers in the future.
The modelling will be used to get a better understanding on the overall hydrological processes in the upper Dudh Koshi basin (overland flow, snow and glacier melt, evapotranspiration, groundwater). After a phase of calibration and evaluation of the model using a dedicated sensitive analysis approach, the model will be run on a longer period of time. This modelling experiment will be used to: (i) establish some hydrological signatures to characterize catchment behaviours; (ii) compare the observed and simulated signatures to enable a diagnostic on how well the model is parametrized, which processes are well or badly represented; (iii) estimate the contribution of the main hydrological processes to total streamflow, their uncertainties and the annual and inter-annual variability and; (iv) highlight the links between climate and glacier evolutions and the sustainability of the hydrological budget and their impacts on the availability of water for people uses.

Updated on 8 April 2022