Glacier contribution to the North and South Saskatchewan Rivers

The hydrological model WATFLOOD and a volume-area scaling relationship are applied to estimate glacier wastage and seasonal Melt contribution to the headwaters of the North and South Saskatchewan Rivers on the eastern slopes of the Canadian Rocky Mountains from 1975-1998. Wastage is defined as the annual volume of glacier ice melt that exceeds the annual volume of snow accumulation into the glacier system, causing an annual net loss of glacier volume. Melt is defined as the annual volume of glacier ice melt that is equal to, or less than, the annual volume of snow that does not melt from the glacier and instead accumulates into the glacier system. It is proposed that the distinction between these two components of glacier runoff is important in studies of the impact of glacier variations on flow. A comparison of similar glacierised and non-glacierised basin hydrographs shows that glacierised basins have greater specific streamflow in the late summer months of otherwise low flow, and the presence of glaciers in a basin results in a lower coefficient of variation of the July to September and annual streamflow as a result of the natural regulating impact of glaciers on streamflow. Glacier wastage and Melt are estimated from a hydrological-hypsometric comparison of glacierised and non-glacierised basins, mass balance data from Peyto Glacier and the published work of other researchers. The similarity of these results to those from the volume-area scaling approach indicates that this is a suitable method for estimating glacier wastage on a regional scale. Whilst the WATFLOOD results were similar to those from the hydrological-hypsometric approach regionally, there were considerable differences between the estimates of combined glacier wastage and Melt from different methods in the small, highly glacierised Peyto Glacier basin. The WATFLOOD results, and thus the estimates of Melt, are therefore treated with caution and it is proposed that glacier runoff data is collected with which to improve the model calibration, verify results and make uncertainty estimations, currently prevented by the severe lack of data on glaciers in the North and South Saskatchewan River basins. The results show that glacier wastage was smaller than Melt and varied between glaciers, though contributed over 10% to streamflow in a number of basins in the July to September period 1975-1998. Melt was positively correlated with basin glacier cover and contributed over 25% to streamflow from basins with glacier cover as little as 1% in the July to September period. The significance of Melt is manifest in its timing since it is equal to the annual volume of snow that accumulates into the glacier system, the volume of which melts as ice instead of snow thus entering the stream in the later summer months after snowmelt. Future glacier decline is therefore expected to result in an advancement of peak flow towards a snowmelt regime hydrograph, assuming that post glacial basin conditions do not similarly delay snowmelt runoff. The resulting reduced late summer flow, compounded by decreasing wastage contributions, is a concern for agricultural and industrial streamflow users, such as hydropower plants, and threatens ecological habitats. Downstream at Edmonton and Calgary, glacier wastage contributed approximately 3% of streamflow 1975-1998; however, Melt supplied over double this volume of flow thus the concern here is whether reservoir capacities are large enough to store a sufficient volume of the spring peak flow to meet supply needs in the late summer months of decreasing flows

Snow modelling for understanding human ecodynamics in periods of climate change

Leverhulme Trust : Grant F/00152/QNational Science Foundation NSF grant ARC114010; NSF grant ARC1104372; NSF grant ARC1145300 IPYThis thesis tests and applies a new, physically based snow distribution and melt model at spatial scales of tens of metres and temporal scales of days across sub-arctic landscapes, in order to assess the significance of snow variability in sub-arctic human ecodynamics at resolutions relevant to human activities. A wider goal is to contribute to planning in the face of future climate change. Model tests are undertaken based on original field data collected in Sweden and Norway, and secondary data from Idaho, France and Greenland. Model applications focus on the ‘completed experiment’ of the medieval Norse in Greenland, a comparatively isolated population that relied on a combination of pastoralism and hunting for survival. A combination of local calibration based on contemporary meteorological data, customised climate reconstructions based on GCM data, new archaeological survey and new DEM are used in order to apply the model. This thesis shows, for the first time, the likely range of snow depth and duration experienced across the medieval Norse Greenland landscape as a result of climate and vegetation change. Results show that increases in snow cover could have been significant drivers of transformative change in Norse Greenland, and are therefore likely to be key in understanding the potential impact of future climate changes on similar sub-arctic and relatively marginal communities. Selected model analyses simulate the total spring (April-June) snow cover at the homefields to range from 32% cover lasting 6 days in the most favourable climate to 100% cover lasting 45 days in the most unfavourable climate at key elite inner fjord farms. At the more isolated outer fjord farms, total spring snow cover ranges from 33% cover lasting 10 days in the most favourable climate to 100% cover lasting 60 days in the most unfavourable climate. Increased climate variance and recovery times, as experienced by the Norse, are potential early warning signals of threshold-crossing change. Model results show that these signals could have been masked for the Norse decision making elite because they were located in the most favourable and least snow covered locations. Masking could have been further increased through the intensified seal hunting implemented by the Norse as an adaption strategy, and these actions could have developed into a rigidity trap. When the conjunctures of the 15th century developed in terms of increased sea ice, snow cover, storminess, culture contact, changing trade and sea level rise, it was too late to develop different responses. Whilst current populations have improved technology and knowledge relative to the Norse Greenlanders, there is a risk that adaptations will lack long-term utility, spatially restricted indications of change may be ignored, and rigidity traps develop. This thesis provides an additional tool for understanding a key element of both the past and possible futures of subarctic human ecodynamics