Trajectories of Channel Adjustments of the Toce River (Northern Italy)

Abstract

An analysis of channel changes of the Toce River (Northern Italy) was carried out with the main aim of identifying the trajectories of channel adjustments. A first phase consisted of a general characterization of the catchment and a division of the river into homogeneous reaches. A systematic analysis of topographic maps and aerial photographs was then carried out using a Geographic Information Systems. The analysis of channel changes showed a progressive reduction of channel width through time. Width adjustments were intense along the upstream braided or wandering reaches, while decreased along the downstream single-thread reaches. Downstream the town of Pieve Vergonte, between 1954 and 1988 (period of maximum local industrial activity), channel narrowing was significant, varying in a range of several meters. The present riparian portions derived from vegetation encroachment of alluvial surfaces before channel narrowing are the preferential sources of sediment delivery from lateral mobility.