Sediment Transfer through the Fluvial System (Proceedings of a symposium held in Moscow, August 2004). IAHS Publ. 288, 2004, 276–282

1 Autorità di Bacino dei fiumi dell’Alto Adriatico, Dorsoduro 3593, I-30123 Venice, Italy

2 Present address: Dipartimento di Geografia, Università di Padova, via del Santo 26, I-35123 Padova, Italy

3 Dipartimento di Ingegneria Civile, Università di Firenze, via S. Marta 3, I-50139 Florence, Italy

Abstract In response to various types of human impacts, most Italian rivers have experienced considerable channel adjustments during the last two centuries. Human impact includes reforestation, channelization, construction of dams and sediment mining. The most important effect of human impact has been an alteration of sediment fluxes, and specifically a remarkable decrease in sediment supply to river channels. The five rivers selected in northern Italy (Tagliamento, Piave, Brenta, Trebbia and Vara), which have or used to have a braided morphology, have undergone channel narrowing (between 58 and 85%), decrease of braiding intensity and incision (up to 4–5 m). Narrowing and incision have been the dominant processes during the last two centuries, particularly intense from the 1950s to the 1990s; however, recent data suggest that those processes could now be exhausted since other kinds of adjustments, specifically channel widening and (local) aggradation, have occurred during the last 10–15 years.

Key words braided rivers; channel adjustments; channel narrowing; channel widening; human impact; Italian rivers; sediment fluxes