L. Mao

Medium Term Fluvial Island Evolution InRelation With Flood Events In The Piave River

River islands could be defined as discrete areas of woodland vegetation surrounded by either water-filled channels or exposed gravel which exhibits some stability, and remain exposed during bunk-full flows. Islands are important from morphological, functional, and ecological points of view. The aim of the present study is to analyze the dynamics of stable, young and pioneer islands in the Piave River, which suffered intense and multiple human impacts especially due to dam building and in-channel gravel mining. Plan-form changes of river features from 1960 were analyzed using aerial photos, and a LiDAR was used to derive the maximum, minimum and mean elevation of island surfaces and the maximum and mean height of the island vegetation. The results suggest that stable islands lie at higher elevation than young and pioneer islands, and are characterized by a thicker layer of fine sediments deposited on their surfaces after big floods. There was a progressive decrease in the active corridor area from 1960 to 2006. After the 1966 exceptional flood (RI> 200 years) there was a moderate increase of island extend and numbers, followed by a further increase from 1991, due to a succession of flood events, in 1993 and 2002 with RI> 10 years, as well as a change in the anthropic management characterized by a control relating to mining activities. The narrowing trend (1960-1999) of the morphological plan-form, certainly enhanced the chance of the island to become stable and this explains the reduction of active channel, the increase of stable island and the reduction of pioneer island. Even though a general channel Monitoring, Simulation, Prevention and Remediation of Dense and Debris Flows IV 161 www.witpress.com, ISSN 1743-3533 (on-line) WIT Transactions on Engineering Sciences, Vol 73,

Role and management of in-channel wood in relation to flood events in Southern Andes basins

This paper analyses the connection among wood dynamics, channel morphology and flood risk in mountain basins of the Southern Chilean Andes and of the Argentinean Tierra del Fuego. Guidelines for the management of in-channel wood and of the riparian buffer strip are suggested, along with considerations about possible input from landslides and debris flows. A selection of low-impact check dams specifically designed for the retention of floating LW elements is finally provided.

Formation, expansion and restoration of a sedimentation fan: the case of the Arroyo del Partido stream (Spain)

The Arroyo del Partido is a small stream flowing into the Donana National Park marsh. In its lower part, the stream used to flow in a wide, low-gradient area, where the channel was highly dynamic with frequent avulsions. As a result of a channel rectification, the subsequent floods heavily eroded the artificial banks and created over time a depositional fan within the Donana marsh. The bedload dynamic at the annual scale was estimated from the expansion of the sedimentation fan, assessed from aerial photographs analysis and repetitive topographic surveys. The bedload transport ranged from 3.7×10