Protected stilling basins downstream of low-head river training structures.

Stefano Pagliara, Michele Palermo

Monday 29 june 2015

17:48 - 17:51h at Europe 1 & 2 (level 0)

Themes: (T) Hydro-environment, (ST) Ecohydraulics and ecohydrology, Poster pitches

Parallel session: Poster pitch: 3G. Environment - Ecohydraulic

Low-environment impact structures have become very popular in the last decades. They are widely used in river restoration both to control sediment transport and, at the same time, to create optimal conditions for fish species in the river. They generally improve water quality due to higher oxygenation. Nevertheless, these are complex structures which require a particular attention to the effects of their presence on the local eco-system. Among this structure typology, block ramps are probably the most common. They are characterized by a quite complex flow regime and by significant erosive processes occurring downstream of them. Therefore, the knowledge of both hydraulic characteristics and scour morphology in the downstream stilling basin is a fundamental aspect for a correct functioning of the structure. In particular, the downstream stilling basin morphology strongly depends on both hydraulic and geometric parameters. Namely, the stilling basin geometry has to be carefully analyzed in order to prevent structural collapse and to create opportune pools where fishes can find an optimal natural habitat. This paper focuses on these last two aspects. The analysis of the stilling basin morphology is conducted in the presence of protection structures (sills) located in the stilling basin in order to minimize scour characteristics. Two stilling basin configurations were tested: prismatic configuration having the same width of the ramp and symmetrically enlarged configuration. The scour morphology for both the tested configurations was analyzed and discussed emphasizing both the similitudes and differences due to the different spatial positions of the sills.