Hydromorphology and land use at different spatial scales: expectations in a changing climate scenario for medium-sized rivers of the Western Italian Alps

Abstract

The study presents an investigation of the relationships between hydromorphological features and land use in two medium-sized Italian Alpine catchments. The South European River Habitat Survey (SE_RHS) method was applied in the collection of hydromorphological data. Five different spatial scales ranging from catchment to site scale were considered for the quantification of land use. Separate Principal Component Analyses for grouped data sets were run on hydromorphological variables related to different spatial scales and the type of information provided. The analyses demonstrated that the most important gradients are related to channel stability. Unstable river reaches, characterized by a significant presence of unvegetated bars, were predominantly related to natural land use. On the contrary, more stable river reaches, characterized by the presence of vegetated bars, were found to be related to anthropogenic land use. High turbulence flow types appeared to be associated with urban and industrial land use. The climate scenario predicts a general increase in temperature, a slight decrease in precipitation, a more dynamic discharge regime and an increase in extreme events, all of which may produce considerable modifications to present agricultural and river management practices. A conceptual model based on the situation observed in the studied catchments is presented, that can be used to infer possible land use changes, during climate variation, in areas adjacent to rivers.