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Water resources and demand
Published in Nick F. Gray, Water Science and Technology: An Introduction, 2017
Global climate change is gradually reducing available water resources but simultaneously creating a greater demand putting surface waters at risk ecologically. Peak water is reached when the rate of water demand exceeds the rate at which water resources used for supply can be replenished. In theory, all water supplies can be considered as finite as they can all be depleted by over-exploitation. So while the total volume of water in the hydrological cycle remains the same, the availability of water alters. This is particularly true of aquifers (groundwater) and static water bodies such as lakes and reservoirs where the water may take a long time to replenish. Water availability is strongly linked to rainfall and the ability to retain this water within resources, which is difficult as increasing intensity of precipitation reduces infiltration. Due to increasing demand from population growth, migration to urban centres and for agriculture, it is possible that a state of peak water could be reached in many areas if present trends continue. By 2025, it is estimated that 1.8 billion people will be living with absolute water scarcity and in excess of 4 billion of the world's population may be subject to water stress.
Current and future projections of glacier contribution to streamflow in the upper Athabasca River Basin
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2020
M. Chernos, R. J. MacDonald, M. W. Nemeth, J. R. Craig
Given that projections of glacier retreat, warmer air temperatures and increased precipitation are relatively consistent across much of globe’s continental mountain ranges (e.g. Huss and Hock 2018), many of these findings in the ARB likely extend to other glacierized basins, although the magnitude of change likely hinges most critically on the percent of glacial coverage and the projected rate of retreat. Huss and Hock (2018) find peak water has passed or is expected to pass within the decade in basins dominated by smaller glaciers, while there is additionally a positive correlation between later date of peak water and glacier size. Glaciers in the upper ARB cover the highest elevations of the Canadian Rocky Mountains and receive some of the highest precipitation totals in the range. These factors will likely allow some glaciers in the ARB to persist longer than further south in the North Saskatchewan and Bow River Basins (Clarke et al. 2015), where glacier contributions are already smaller than in the upper ARB (Marshall et al. 2011). Conversely, the Coast Mountains in south-western British Columbia receive substantially more precipitation than the Rocky Mountains and are projected to survive longer, albeit in a diminished state (Clarke et al. 2015).
Modelling historical and potential future climate impacts on Keremeos Creek, an Okanagan-Similkameen watershed, British Columbia, Canada: Part I. Forecasting change in spring and summer water supply and demand
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2019
Shaghayegh Mirmasoudi, James Byrne, Ryan MacDonald, Daniel Johnson, Roland Kroebel
Snowmelt started in April, achieved a peak in June, and then decreased through July and August for the 1961–1990 period (Figures 3 and 8). However, the onset of snowmelt may shift earlier in March with the primary spring water volume between March and June with a peak in May for RCP 4.5 in the 2020’s. This pattern is the same for all other projected periods and emission scenarios except RCP 8.5 in the 2080’s, in which the timing of snowmelt may start 2 months earlier and extend through February and May with a peak in April (Figure 8). An earlier timing of snowmelt in all projected periods and emission scenarios is to be expected as a function of air temperature increasing over the watershed (Figure 5 and 8). According to the results, the peak water volume at the outlet of the watershed may decrease for RCP 4.5 and 8.5 in the 2020’s, 2050’s, and 2080’s relative to the average historical value (Figure 8). The reduction in peak water volume at the outlet of the watershed is a function of possible decreases in the ratio of snow to total monthly precipitation due to air temperature increases in all emission scenarios and projected periods (Knowles et al. 2006; Schnorbus et al. 2014; Elsner et al. 2010; Mote et al. 2005). If more of the precipitation occurs as rain than snow, the available water storage in the form of snow decreases and results in lower snowmelt runoff (MacDonald et al. 2011).