Climate change and European rivers: An eco-hydromorphological perspective

Climate change is expected to modify temperature and precipitation patterns throughout Europe, leading to warmer drier summers; wetter, milder winters; and an extended growing season. Alterations to feedbacks between important eco-physical structuring processes driven by climate change may modulate river morphology, floodplain characteristics, and their biological communities. Current understanding is reviewed and synthesised to explore the potential responses, mechanisms, and ramifications of climatic shifts for the European riverscape. Fundamental drivers of change are expected to be (a) disturbance deviation beyond the historical norm and (b) vegetation morphodynamics, a key river process where ecological and fluvial-geomorphological attributes interact to shape the physical environment. Increased seasonal temperature, summer drought, and winter flooding may affect the colonisation, growth, and mortality of plant species with consequences for riverscape structure and function as succession patterns adjust with repercussions for hydraulics and sediment dynamics. Such opposing winter and summer climate regimes are likely to impact vegetation patch dynamics, reflected in an increasingly variable patch mosaic as disturbance intensity deviates further from historical background conditions. How changes to climate drivers manifest themselves in individual river systems will also be affected by attributes such as catchment topography, geology, vegetation type, and previous human alterations. Where large scale change occurs, it will have consequences for the type and function of biological communities inhabiting the riverscape. Conventional engineering responses to meteorological disturbance will amplify the effect on river biota by reducing their ecological resilience, highlighting the need for a management response that integrates ecological and societal benefits simultaneously.