Springtime flooding dynamics in the Upper Wolastoq Basin based on regional climate model simulations
University of New Brunswick
Spring flooding of the upper Wolastoq (Saint John River) basin, northeastern North America, poses a significant threat to present and future socio-economic development in the area. The spring floods of 2008 and 2018 were two of the more devastating 100-year floods affecting the basin in the past century. The objective of this study was to investigate flooding trends in the Wolastoq by tracking the daily evolution of hydroclimatic variables (e.g., air temperature, precipitation, snow accumulation, snowmelt patterns, surface runoff) and waterflow dynamics in the river from 2007–2019 based on an implementation of a regional climate model, namely RegCM4. The model’s simulation provided reasonable fidelity in identifying the precise timing and magnitude of both the 2008 and 2018 flooding events. The impacts of forest-cover removal on the Wolastoq discharge rates were also examined. The surface landcover in model simulations was digitally altered from forests to agricultural lands (crops + irrigated lands) in emulating annual forest-cover removal and accumulation for 2008 and 2018. The study indicated that cumulative annual forest disturbance in the upper basin based on % forest-cover removal rates defined by Global Forest Watch products, tended to increase spring’s peak discharge rates in the upper Wolastoq from 27% in 2008 to 55% in 2018.