Resumen

CASADO, Ana. Influence of the stream structure on longitudinal gradients of thermal recovery in regulated rivers, Sauce Grande River (Argentina). Rev. Univ. geogr. [online]. 2017, vol.26, n.1, pp. 57-77. ISSN 1852-4265.

Dams and reservoirs alter downstream river water temperatures over a range of time and spatial scale. The thermal effects of dams are more noticeable immediately downstream and may persist along several kilometers. The distance for river thermal recovery depends on a combination of factors driving and buffering heat exchange among the river, the aquifer and the atmosphere. Therefore, such distance varies significantly along regulated rivers. This study analyzes the influence of the stream structure on patterns of thermal recovery of the Sauce Grande River, Argentina. Nine indicators of topographic, morphologic and hydrologic influence are used in summer and winter water temperatures at eight different sites. Seasonal gradients of thermal recovery were irregular, and the thermal effects of the dam remained the same along 15 km monitored during both periods. Water temperature along the first 8 km was influenced by riparian vegetation and showed seasonal differences related to distinct riparian vegetation density. Irrespective of the season, down water temperatures were progressively influenced by hyporheic and phreatic flow. These findings underline the complex relationship between drivers and buffers of stream water temperature and trigger further research on the ecohydrology of this highly regulated river.

Palabras llave : Regulated Rivers; Water Temperature; Stream Structure; Thermal Recovery; Sauce Grande River.