Tidal, hydrological and meteorological contributions to high-water level events in the Saint Lawrence River Estuary: Local responses to regional drivers
Year: 2026
Type: article
Abstract: Extreme water levels in estuaries exhibit considerable variability on multiple spatial and temporal scales, driven by complex responses to coastal, hydrological, meteorological, geological, and anthropogenic factors. These factors complicate the prediction of high-water level events and their characteristic. Although extensive literature exists on hydroclimatic and coastal extremes, few studies conduct comprehensive statistical analyses that jointly consider multiple drivers and the spatiotemporal variability of high-water-level events in estuaries.This study addresses these gaps by developing a robust statistical framework to identify, characterize and attribute local and regional high-water-level events in the St. Lawrence River Estuary (Canada) over the period 1980–2023. Building on existing approaches, a Generalized Additive Model (GAM) formulation of non-stationary harmonic regression is used to decompose the water level variability at 11 gauging stations, with automated selection of covariates and tidal constituents. This decomposition quantifies the relative contributions of the underlying processes, enabling event classification according to their dominant coastal, tidal, or fluvial drivers. Distinct spatial patterns of tidal and non-tidal processes are observed along the fluvial estuary and tidal river, and a specific transition zone is identified between these two. The results indicate that non-stationary dynamics are distinct in different tidal and non-tidal frequency bands.The resulting event classification also demonstrated a different landward shift from coastal to hydrological drivers for tidal and non-tidal non-stationarity. These findings guide the statistical analysis and configuration of the hydrodynamic models used in meteorological forecasting, climate projections, and other specific applications.
Source: Weather and Climate Extremes
Authors: Silvia Innocenti, Marianne Fortier, Pascal Matte, Caroline Sevigny, Remi Gosselin, Olivier Champoux
Institution: Environment and Climate Change Canada
Language: English
Topic: Coastal and Marine Dynamics
Subfield: Earth-Surface Processes
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,969
OpenAlex ID: W7123676640