The influence of riparian vegetation shading on water temperature during low flow conditions in a medium sized river
Stream water temperature limits the growth and survival of aquatic organisms; whereby riparian shading plays a key role in inhibiting river warming. This study explains the effects of riparian shading on summer water temperatures at a pre-alpine Austrian river, during heatwave and non-heatwave periods at low flow conditions. A vegetation-shading index was introduced for the quantification of riparian vegetation effects on water temperature. For maximum water temperatures, a downstream warming of 3.9 °C was observed in unshaded areas, followed by a downstream cooling of 3.5 °C in shaded reaches. Water temperature directly responded to air temperature and cloudiness. For an air temperature change of 2 °C we modelled a water temperature change of 1.3 °C for unshaded reaches, but lower changes for intensively shaded reaches. Similar daily variations at shaded reaches were up to 4 °C lower than unshaded ones. This study gives clear evidence that for a medium-sized pre-alpine river, restoration practices should consider that discontinuity of riparian vegetation should be less than 6000 m; with more than 40% dense vegetation in order to minimize water temperature increases due to unshaded conditions.
Auteurs du document :
Gerda Kalny, Gregor Laaha, Andreas Melcher, Heidelinde Trimmel, Philipp Weihs, Hans Peter Rauch
Obtenir le document :
EDP Sciences
Mots clés :
riparian vegetation, vegetation-shading index, water temperature, river vegetation management, restoration, végétation riveraine, indice d'ombrage de la végétation, température de l'eau, gestion de la végétation des rivières, restauration
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