Climate change impacts on snow and streamflow drought regimes in four ecoregions of British Columbia

Abstract

Abstract. In many regions with seasonal snow cover, summer streamflow is primarily sustained by groundwater that is recharged during the snowmelt period. Therefore, below-normal snowpack (snow drought) may lead to below-normal summer streamflow (streamflow drought). Summer streamflow is important for supplying human needs and sustaining ecosystems. Climate change impacts on snow have been widely studied, but the relationship between snow drought and streamflow drought is not well understood. In this study, a combined investigation of climate change impacts on snow drought and streamflow drought was completed using generic groundwater – surface water models for four headwater catchments in different ecoregions of British Columbia. Results show that, in response to increased precipitation and temperature, the snow drought regime changes substantially for all four catchments. Warm snow droughts, which are caused by above-normal winter temperatures, increase in frequency, and dry snow droughts, which are caused by below-normal winter precipitation, decrease in frequency. The shift toward more frequent and severe temperature-related snow droughts leads to decreased summer runoff, decreased summer groundwater storage, and more extreme low flows in summer. Moreover, snow droughts propagate into summer streamflow droughts more frequently in the future time periods (2050s, 2080s) as compared to the baseline 1980s period. Thus, warm snow droughts not only become more frequent and severe in the future but also more likely to result in summer streamflow drought conditions.

A 21st‐Century perspective on snow drought in the Upper Colorado River Basin

“…This, combined with earlier and slower snowmelt instigated by a warming climate (Barnhart et al, 2016), has been shown to lead to reductions in below-root zone percolation and overall baseflow efficiency. Similarly, the severity of low-flow periods in the summer and winter, driven by snowmelt-recharged groundwater, has also been linked to a reduction in winter season precipitation (Dierauer et al, 2018(Dierauer et al, , 2020Godsey et al, 2014). Particularly under drought conditions, the role snowpack plays in the attenuation and storage of precipitation before becoming runoff and groundwater recharge makes it a critical component of the UCRB hydrologic cycle.…”

“…Particularly under drought conditions, the role snowpack plays in the attenuation and storage of precipitation before becoming runoff and groundwater recharge makes it a critical component of the UCRB hydrologic cycle. However, the implications of snow drought for UCRB hydrology and water resources management have yet to be thoroughly explored (Dierauer et al, 2020).…”

“…Streamflow volume and timing in most headwaters regions across the western United States (U.S.) are dependent on melt from snowpack (Hall et al, 2012; Li, Durand, et al, 2017; Liu et al, 2015; Mahanama et al, 2012; Miller & Piechota, 2011). Snowpack variability is largely affected by winter season shifts in meteorology (Barnett et al, 2005; Dierauer et al, 2020; Harpold et al, 2014), such as temperature increases (McCabe & Wolock, 2007; McCabe et al, 2017; Stockton & Boggess, 1979; Udall & Overpeck, 2017; Woodhouse et al, 2016) and precipitation deficits (Cayan et al, 2010; Cline, 1997; Dierauer et al, 2018). Historically, the term “snow drought” has been used to characterize the general condition of anomalously low snowpack (Cooper et al, 2016; Ludlum, 1978; Wiesnet, 1981), yet classification of snow drought types as a consequence of distinct meteorological processes has only recently gained traction (e.g., Harpold et al, 2017).…”

A global algorithm for identifying changing streamflow regimes: application to Canadian natural streams (1966–2010)

“…C2 is very similar to C1, however with greater variability in annual streamflow hydrographs. The streams belonging to this stream type are mainly concentrated in western Canada, particularly in the Montane Cordillera (46 % of streams), and include streams that are fed mainly through snow and glacial melts (Eaton and Moore, 2010;Moore et al, 2012;Schnorbus et al, 2014). There are, however, streams belonging to C2 that are located in the Boreal Shield (23 % of streams), where the streamflow generation is governed by other processes such as fill-andspill in which segments of a basin have to be filled above their capacity before spillage (Spence and Phillips, 2015).…”

A novel algorithmic framework for identifying changing streamflow regimes: Application to Canadian natural streams (1966–2010)

“…Climate change impacts on natural streamflow regime are more severe in higher latitudes such as in Canada (e.g., Nijssen et al, 2001;Déry and Wood, 2005;Hinzman et al, 2005;Leclerc and Ouarda, 2007;IPCC, 2013;DeBeer et al, 2016;Brahney et al, 2017;MacDonald et al, 2018;Islam et al, 2019;Champagne et al, 2020Dierauer et al, 2020, where the rate of warming is twice of the global average (Bush and Lemmen, 2019). Both observed and projected changes in Canadian streamflow characteristics are subject to significant spatial variabilities (e.g., Burn et al, 2010;Buttle et al, 2016;O'Neil et al, 2017).…”