A standardized characterization of river thermal regimes in Québec (Canada)

Abstract

The availability of Québec (Canada) river temperature data has improved significantly in recent years, with increased monitoring effort and sharing of existing data. Although it is now recognized that this variable is of central interest in a variety of instream habitat issues, the actual interpretation and use of the data by managers and researchers can be challenging, due to the spatial sparsity of the measurement sites and to the unevenness of the length of the temperature time series. In this paper, we propose a model for all Québec rivers thermal regimes, as a means to interpret and exploit the available river temperature data. The model, based on fitting a Gaussian function to time series of interannual mean daily temperatures, was used to characterize the thermal regime at more than 400 locations in Québec rivers. The three parameters of the model (annual maximum, date of annual maximum and length of the warm season) allowed to produce a first map of Québec river thermal regimes. A method to quantify the uncertainty on the parameters estimation, taking into account the length of the time series and the interannual variability of the river temperature, is presented. Finally, stepwise regressions were used to investigate the relationships between the model parameters and the physioclimatic characteristics of the basins upstream of the measurement sites.