Investigation of the projected impacts of climate change on the hydrology of Labrador's Churchill river basin using multi-model ensembles

Roberts, Jonas (2015) Investigation of the projected impacts of climate change on the hydrology of Labrador's Churchill river basin using multi-model ensembles. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

This manuscript thesis presents four stand-alone papers which all contribute to the investigation of projected impacts of climate change on the hydrology of Labrador’s Churchill River Basin. The overarching goal of this undertaking was to provide useful information to Nalcor Energy, a hydroelectric developer, regarding the change in the amount and timing of water in the Churchill River between a base period (1971-2000) and a future period (2041-2070). Three separate multi-model approaches used data from the North American Regional Climate Change Assessment Program to look at the impacts of climate change on the Churchill River: (i) Bias-corrected precipitation and temperature data forced a hydrologic model to investigate the changes in mean daily streamflow for the Pinus River, a subbasin of the Churchill River; (ii) A new approach (dubbed “fullstream analysis”) took advantage of the full range of simulated hydrological variables from each ensemble member and was used to study the expected changes in mean annual runoff of the entire basin, and; (iii) Weighted multi-model ensembles examined the simulated impacts of climate change on mean monthly runoff for the entire basin. Several results were common across the various approaches. Ensemble mean annual increases in runoff were found to be similar, between 8.9% and 14.6%. Further to this, an increase in cold-season runoff amounts, an earlier onset of the spring melt (though not necessarily a larger spring melt) and no discernable change in the late summer and early fall runoff were found. In an effort to further understand sources of error and uncertainty of the climate models used, water balances were investigated and the annual cycle of residuals quantified. Residual magnitudes varied widely between months and models and were dependent on whether one examined atmospheric or terrestrial balances. Water balance residuals remained relatively consistent between time periods implying they are systemic and not climate dependent.

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