How natural are Alpine mountain rivers? Evidence from the Italian Alps

Abstract

Historical, human‐induced channel adjustments in lowland gravel‐bed rivers have been documented in several geographical contexts worldwide. In particular, it is now widely accepted that the vast majority of European rivers are far from any natural, reference state prior to anthropic disturbances, and a ‘complete’ restoration is hardly achievable. However, few investigations have addressed changes that have occurred in mountain rivers of the Alps, and these channels are commonly reckoned quite ‘natural’ by society. This paper intends to describe how human pressure on Italian Alpine basins has been quite relevant for several centuries – in terms of land‐use variations, in‐channel structures, timber transport (splash damming) and riparian vegetation management – such that nowadays ‘reference conditions’ cannot be found even in small mountain creeks. In addition, recent natural climatic variations (e.g. the Little Ice Age) are superimposed on human disturbances, thus defying the definition of any ‘equilibrium’ morphological conditions even under ‘human‐free’ states. A summary of published as well as unpublished works on historical channel adjustments in rivers of the Italian Alps is presented in order to document the impacts deriving from human pressure at different basin scales and for different river morphologies, from steep confined streams to large unconfined rivers. General options for river management and restoration actions aiming to combine geomorphological functionality and flood hazard mitigation are discussed, in the light of the current European legislative context. Copyright © 2011 John Wiley & Sons, Ltd.

A method for the assessment and analysis of the hydromorphological condition of Italian streams: The Morphological Quality Index (MQI)

“…Most fluvial systems in Europe (e.g., Petts et al, 1989;Billi et al, 1997;Comiti, 2012)-as well as in other continents (e.g., Montgomery, 2008)-have been affected by humans for several centuries or even thousands of years, rendering fluvial systems the result of a long interplay between climatic, geological, and human factors. This evidence led many authors to conclude that referring to a 'pristine' stream condition is neither feasible nor worthwhile (e.g., Kern, 1992;Rhoads and Herricks, 1996;Rhoads et al, 1999;Jungwirth et al, 2002;Downs and Gregory, 2004;Kondolf and Zolezzi, 2008;Piégay et al, 2008;Dufour and Piégay, 2009;Wyżga et al, 2012).…”

“…In this respect, the work of Jungwirth et al (2002) is valuable because it emphasizes that assessment can be a two-step process, i.e., firstly, deviations from natural conditions ('visionary leitbild') are assessed, followed by the identification of restoration goals ('practical leitbild'). The appropriateness of identifying river 'degradation' history before reasoning about possible restoration actions has recently been argued for Alpine rivers by Comiti (2012).…”

Multi-Temporal Image Analysis for Fluvial Morphological Characterization with Application to Albanian Rivers

“…A complementary ingredient for effective environmental management would be to understand the causes and controls of those evolutionary river trajectories. Broadly speaking, the decrease of active channel width has been explained by the concurrent effect of different factors, including climate change, land use change, dam construction and in-channel gravel mining [49]. The present study does not attempt to account for the causality of the observed changes on the selected Albanian rivers; for this, further research is needed.…”

Towards a better understanding of the today French torrents management policy through a historical perspective

“…The beginning of the 19 th century corresponds to the end of the Little Ice Age, a cold period with a high sediment transport and hydrologic activity [20]. As a distant consequence, aggradation and widening of some rivers was observed [21], and stream beds and fluvial activity areas were larger than today.…”