Exploring the effects of climate change and glacier loss on streamflow predictability

In mountainous, regulated stream networks, shifts in the composition and/or variability of summer streamflow can affect its predictability and have compelling operational consequences. While glaciers can contribute significantly to summer flow, few studies have explicitly modelled the ongoing glacier recession in many parts of the world in conjunction with the other primary hydrological processes. In this talk I present work our group has performed to incorporate glacier dynamics from the Regional Glaciation Model (RGM) into the UBC Watershed Model (UBCWM) and quantify streamflow contributions from snowmelt, glaciers, and rain-sourced runoff via the Raven modelling framework. The talk will focus mainly on our results in modelling the Mica Basin, a ~20,000 km² regulated watershed containing the headwaters of the Columbia River. Our simulations do not project significant changes in the coefficient of variation of summer runoff, a result which would appear to contrast the conventional conceptualization that glaciers act to attenuate the variability of annual summer flow. Furthermore, despite projecting future reductions in the magnitude of snowmelt and an increased role for rain-sourced flow in the Mica, we find peak snow water equivalent remains a strong linear predictor of summer runoff throughout future simulations. We argue that these somewhat nonintuitive results display the complexities inherit in isolating the effects of changes to a single water balance component when other components are also non-stationary, and highlight the benefits of using modelling to more explicitly explore such implications.

Bio:

Dr. Kai Tsuruta is a Post-Doctoral Hydrologic Scientist at PCIC, where his research focuses on the development and application of fully-coupled landcover-hydrological models to inform future water and landuse-related decision making.