Methods
Snow and runoff regimes are simulated using models created with the Cold
Regions Hydrological Modelling platform, CRHM (Pomeroy et al., 2007).
These models were developed and evaluated with basin observations as per
Fang et al. (2013), Rasouli et al. (2014, 2015) and Rasouli (2017), and
then used to assess the sensitivity of the hydrological response to
climate change in each of the three mountain basins by perturbing the
model forcings.
The sensitivity experiments use the CRHM basin models, driven with
perturbed forcings, to simulate outputs such as snowpack and coverage
dynamics, and the timing and magnitude of runoff to capture the snow
hydrological response to climate model outputs for the future. The
sensitivities of interest are the hydrological responses to increases in
air temperature and changes in precipitation that use the observed time
series of air temperature and precipitation perturbed changes in the
ranges projected by climate models under the Special Report on Emissions
Scenarios (SRES) A2 (business-as-usual) and the Representative
Concentration Pathways (RCPs) of global change for those basins. Rather
than simulations based upon individual climate models, this linear
sensitivity analysis provides an assessment of the scale of alteration
of the hydrological cycle in mountain basins by climate change. This
approach illustrates how the combination of changes in air temperature
and precipitation might induce hydrological changes in these basins.
Knowing how combinations of warming and precipitation changes induce
future hydrological change in mountain basins from northern to
mid-latitudes can be used to assess possible impacts of climate change.