Numerical study of the water discharge on a fish stepped passage at a low head dam

Abstract

Whereby the water course is considered a continuous system with hydrological connectivity – longitudinal, lateral, vertical – and variable in time, the design and implementation of barraging steps on water courses will have to follow the river dynamics and to respect the ecological concepts. Looking to diminish the negative impact on the environment, the promoted technical solution needs to consider a series of principles and criteria specific to the river basin for the conservation of nature and biodiversity. A specific river development assuming the accomplishment of a low head overflowing step ending with a water energy dissipater will have to be additionally endowed, according to nowadays legislation, with a corresponding fishway structure preserving the natural passing. The paper presents a numerical simulation of the water discharge transported by the fish stepped passage associated to the low head overflowing Livezeni Dam on Jiu River in Hunedoara County, Romania, considering the possible accidental high waters phenomenon given as a synthetic levels’ hydrograph. The hydraulic model looks to analyse the maximum discharges for the special structure and also to estimate the maximum values for water velocity in the strangled cross sections. As a consequent, the adjustment of the steps geometry or number can be studied in order to fulfil the nowadays regulation on the subject.