Processi di approfondimento dell'erosione in alveo ed effetti dell'inquinamento nei fiumi delle Marche centro-meridionali (Italia centrale)

Abstract

: Farabollini P. et al., Deepening erosional fluvial processes and effects of water pollution in the middle-southern marchean
rivers (central Italy) (IT ISSN 0394-3356 2008).
Many modern geomorphological studies on fluvial dynamics carried out on some Italian rivers highlighted that intense and showy erosion processes affect them and interpreted this mostly as the result of human intervention: their morphological effects, notwithstanding the short duration of processes, are somehow comparable with those produced by Pleistocene climatic variations.
The attribution of such phenomena to more or less direct influence of different anthropic activities on fluvial dynamics demonstrates
that hydrographic systems are among the components of the physical environment that reacts more quickly to environmental changes.
This paper aims at deepening our understanding of the topic and derives from detailed geomorphological surveys, sided by geotechnical analyses, carried out during the last decade along the reaches of the marchean rivers (Central-Southern Marche, Adriatic side of Central Italy). Notwithstanding the short duration of observation, it was possible to observe relevant geometric variations of river beds that can be unquestionably attributed to human activities.
Recent detailed investigations on some streams highlighted the activity of intense erosional processes, mostly valleyward of some purifiers. There, erosion is probably triggered or accelerated by water pollution that causes the breaking of particular ionic links, especially in clay minerals.
Another contribution to stream deepening, whose rate sometimes reaches some meters in few years, is given by the strong and ever
increasing occupation of alluvial plains for human purposes. In such situation, it is to be evidenced that drainage is often obstacled in
links between main and secondary hydrographic network.
Another erosional process takes place downstream of confluences of artificial water channels (private or public), where discharge and
solid load increase, resulting in more intense lateral erosion and downcutting.
Finally, the notable extraction of water from alluvial plains is studied since, mainly during Summer, it is not balanced by an adequate
recharge, thus producing important cracking phenomena and, subsequently, leading to further fluvial deepening.