Author(s): Catella Michele; Bechi Giulio; Paris Enio
Linked Author(s):
Keywords: Side weir; River morphodynamics; Numerical model
Abstract: Storage areas are used to prevent flooding of lower lying lands by allocating part of water volume by means of side flow weirs. As a part of the water discharge is diverted from the main channel, its sediment transport capacity decreases. Thus an aggradation process is established along the side weir river reach modifying the design efficiency obtained by fixed bed hydraulic modelling. Recent laboratory observations (Rosier et al., 2006) clarify some aspects related to the deposit formation along the side weir. Moreover one of the major problem on flood control management is the analysis of the river morphodynamics at side weir sites. The present study concerns a one-dimensional numerical model to analyse side weir efficiency by modelling the deposit formation during major floods and evaluating its influence on the discharge to be diverted. The St. Venant – Exner equations, written in a conservative form, are solved by employing a finite volume method, following a decoupled procedure (Catella et al., 2005). The water depth profiles in the main channel along the side weir are computed modifying the De Marchi hypothesis (De Marchi, 1934), and the overflow discharge is evaluated by means of two different equations in the case of free or submerged overflow. Application of the present model to a real case study is finally presented.
Year: 2007