Factors controlling the changes in surface water temperature in the Ebro River Basin

Study region The Ebro River Basin, northeast Spain. Study focus The work analyzes the evolution of water temperature (Tw) in the Ebro River and its main tributaries, its annual cycle and its trends, as well as the effects of various natural and anthropogenic factors on them. New hydrological insights for the region Stations located downstream of nuclear power plants showed an anomalous increase in Tw not consistent with the river section where they are located, with higher values in the lower-flow months (August to December). The stations affected by the main reservoirs along the Ebro River showed a lower annual temperature range and the stations located in large irrigation systems showed a lower summer temperature compared to other stations with similar climatic conditions. Finally, there was a significant annual increase in Tw at all stations (mean ?Tw=0.05 °C/year), except those located at the head of the tributaries. These trends were higher for the stations downstream of the Ascó nuclear power plant (?Tw > 0.08 °C/year). Seasonally, the spring months showed the greatest changes, with higher increases at the stations downstream of Ascó (?Tw ? 0.10 °C/year). The increase in air temperature associated with global warming and the decrease in flows associated with the increase in water consumption resulted in an increase in the temperature of the river.

Thanks are given to Confederacion ´ Hidrografica ´ del Ebro for providing all data series analyzed in this work. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Water temperature

Annual cycle

Trends

Natural factors

Irrigation

Anthropogenic affections

Nuclear power plants

Reservois

Reservois

Published