Development of precipitation δ18O isoscapes for Canada and application within a tracer-aided hydrological model

• Published in: Water Resources Research
• Main Author: Delavau, Carly J.
• Other Authors: Stadnyk,Tricia (Civil Engineering), Rasmussen, Peter (Civil Engineering) Buhay, Bill (Geological Sciences) Birks, Jean S. (Guest Member, InnoTech Alberta) James, April (Geography, Nipissing University)
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Taylor and Francis, American Geophysical Union 2011
• Subjects: Stable water isotopes; Precipitation isoscapes; Isotope hydrology; Hydrological modelling; Uncertainty; Canada; Fort Simpson; Geiger
• Online Access: http://hdl.handle.net/1993/31946

Delineating spatial patterns of precipitation isotopes (“isoscapes”) is important for studies including the hydrology of terrestrial systems, present and past interpretations of climate, and tracer-aided hydrological modelling, among others. However, the extent to which precipitation isoscapes can be predicted across Canada has not been fully articulated. This thesis combines isotopes in precipitation (δ18Oppt) observations from two regional and one global network to create long term and time series precipitation isoscapes for Canada and the northern United States. Multi-linear regressions of a small suite of geographic and climate variables generate the best performing long-term and seasonal models of δ18Oppt. These models are used to develop long term isoscapes for Canada, which capture the general spatial and seasonal trends in δ18Oppt, showing an improvement upon results from previous studies using global models. Building upon long-term δ18Oppt prediction, δ18Oppt observations alongside climatological and geographic predictors are used to create empirical time series prediction models. Five regionalization approaches are used to separate the study domain into isotope zones to explore the effect of spatial grouping on simulations. Generally, the models capture the timing and magnitude of intra-annual (seasonal) δ18Oppt cycles across the study domain while simulating moderate inter-annual variation; however often fail to capture the anomalies in observed δ18Oppt. Uncertainty in predictions is quantified spatially and temporally, and the Köppen-Geiger (Kpn) regionalization is selected as the preferred regionalization scheme for future applications due to adequate model performance and lack of border issues at regional boundaries. Finally, estimates of monthly δ18Oppt from Kpn models, long term annual averages, and daily REMOiso output are used to force an isotope-enabled hydrological model, isoWATFLOOD, in the Fort Simpson Basin, NWT, Canada. Results show streamflow simulations are not significantly impacted by ...