Holly Annand, John Pomeroy, Howard Wheater (2022). The influence of wetland management and climate change on the hydrology of an agricultural catchment in the Canadian Prairies. Proceedings of the GWF Annual Open Science Meeting, May 16-18, 2022.

Wetland drainage has been linked to increased flooding, reduced downstream water quality, and loss of ecosystem services in the Prairie Pothole Region (PPR) of North America. In the northern PPR, future climate projections show increased air temperature and rainfall. The goal of this study was to determine the influence of wetland drainage and climate change on the hydrology of an agricultural catchment in the Canadian Prairies. A physically based prairie hydrological model of the instrumented and heavily drained Smith Creek Research Basin, Saskatchewan, Canada was developed using the Cold Regions Hydrological Modelling platform (CRHM). Key cold regions hydrological processes were represented in the model and an advanced conceptual representation of wetland spill-and-fill hydrology was implemented using depressional wetlands derived from a 2-m resolution DEM. The model was forced with bias-corrected outputs from the Weather Research and Forecasting (WRF) model during a current (2001-2015) and a future pseudo-global-warming period (PGW, 2086-2100). The PGW period represented the RCP8.5 emission scenario, which projected a 5.5 °C increase in mean annual air temperature and a 44 mm increase in annual precipitation. Hydrological modelling results suggest this climate change will increase rainfall and evapotranspiration by 75 mm and 9% respectively and decrease snowfall, blowing snow sublimation and peak SWE by 32 mm, 57% and 44% respectively. Streamflow timing will remain similar, however greater interannual variations in peak and annual discharge are predicted. Spring peak discharge will increase by 34% and summer peak discharge will increase by 161%, resulting in a 26% increase in annual streamflow volume. Continued expansion of wetland drainage is predicted to have more influence on annual streamflow volume than projected climate change if wetland area drops below 9% of the basin area. Conversely, wetland restoration to more than 23% of the basin area will be needed to offset projected increases in annual streamflow volume due to climate change. Complete restoration to historically maximum levels will not be enough to offset projected increases in peak summer discharge. Results from this study are expected to help inform wetland mitigation policy development in the PPR.

AOSM2022 Prairie Water/Ag Water First Author: Holly Annand, University of Saskatchewan Additional Authors: John Pomeroy, University of Saskatchewan. Howard Wheater, University of Saskatchewan.