Author(s): Brian C. Burrell; Spyros Beltaos
Keywords: River Ice; River Ice Breakup and Jamming
Abstract: Ice formation, growth, and breakup along the Saint John River affects its hydraulic and ecological regimes, and leads to the potential for ice jamming that has caused severe flooding and ice runs resulting in loss of life, property damage, and loss of, or damage to, infrastructure. As river ice is often responsible for severe floods and infrastructure damage, an understanding of river-ice processes and hydraulics is essential in designing engineering works in and around natural streams that form ice covers for several months each winter. The focus of the paper is an evaluation of historical ice-related flooding, both in mid-winter and spring, including emerging trends towards earlier breakups and more frequent mid-winter events. A synopsis of typical winter climate and ice-season characteristics along the Saint John River from Dickey, Maine, USA to Woodstock, New Brunswick, Canada, is provided. Midwinter and spring breakup conditions are described, with reference to conditions that existed during past events that lead to ice jamming and associated flooding. Trends in relevant hydroclimatic variables such as monthly mean air temperature (December to April), total winter snow (December to March), length of the ice season, rainfall, and monthly mean and peak winter and spring flows are discussed. Projections of future ice regimes under a changing climate are provided, with anticipated changes in the ice regime of the Saint John River explained in the wider context of changes to the cryosphere.