Author(s): Aj Collados-Lara; Cl Ramon; F. Huertas; D. Pulido-Velazquez; Fj Rueda

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Keywords: Climate change; Air temperature; River water temperature

Abstract: Human-induced climate change will affect the hydrological and thermal dynamic of rivers, potentially impacting freshwater ecosystems and industrial and domestic water use. In this study, we propose a parsimonious methodological framework to assess the impact of climate change on daily river water temperature. We apply our methodology to 17 monitoring stations of the Guadalquivir river basin (south Spain). River water temperatures are generally most sensitive to atmospheric conditions (air temperature) but changes in streamflow can also significantly affect water temperatures, especially with low river flows. We analyze multiple regression models to estimate river water temperature from air temperature and river flow. However, in this case study, we do not observe any significant relationship between river flow and river water temperature (mean R2 0.10). The models that show better results are linear regression models that only include air temperature. We calibrate monthly linear regression models that relate daily air temperature and daily river water temperature for each point obtaining satisfactory results (mean NSE 0.86). These models are used to propagate climate change scenarios generated from an ensemble of 9 Regional Climate Models for the horizon 2071–2100, under the RCP 8.5 emission scenario. The mean change in air temperature and river water temperature predicted is 3.5 ºC and 2.1 ºC. In general, the higher changes are observed in summer with a mean predicted increase of 4.4 ºC and 2.6 ºC respectively. These worrying changes reflect the need to establish water policies based on adaptation and mitigation of the climate change impact on rivers.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p1575-cd

Year: 2023