Dam-induced impacts on the water temperature of the Charef River (north-eastern Algeria)

Context Dams construction appears to have multi-dimensional effects on the river environment, and it especially affects the thermal condition of rivers.Aims The objective of this work was to assess downstream thermal responses to the Charef Dam in relation to the water flow and the water residence time.Methods During the year 2012, the hydrological parameters upstream and downstream of the dam were monitored.Key results Salinity, electrical conductivity, total dissolved solids (TDS) and water flow all responded similarly, with larger magnitudes in waters upstream of the dam than downstream, whatever the season. In terms of flux, the Charef Dam retains 59 and 56% of the incoming water and TDS fluxes respectively. Furthermore, the upstream water temperature is higher than that of the downstream in 83% of samples. During the dry season, the thermal response of the waters downstream of the Charef Dam can exceed 2 degrees C (downstream cooling).Conclusions Despite being a small dam, the water residence time (2.3 years) in the Charef Dam has a significant effect on the downstream water temperature.Implications These temperature changes may cause significant physicochemical and biological issues. Restoration practices such as increasing discharges during dry seasons and riparian cover restoration could mitigate thermal impacts and minimise negative effects.