Impact of the Addition of a Shading Algorithm in a Physically Based Conceptual River Hydrological–Temperature Model

ABSTRACT Anthropogenic impacts on the thermal regime of rivers include climate change and deforestation. For the latter, developing modelling tools that can account for the impact of varying vegetation cover on river temperatures is essential. This study describes a new addition to the CEQUEAU hydrological and water temperature model: a shading algorithm. This relatively simple tool accounts for vegetation height, stream orientation and the associated shadow length on the river to modulate incoming solar shortwave radiation. The algorithm was tested on seven different sites from five Canadian rivers. The results indicate that the algorithm either maintained or slightly improved model performance. Different deforestation and afforestation scenarios were tested and the model showed sensitivity to changes in riparian vegetation height, as a function of width and initial vegetation cover.