Abstract: “The present paper points out that studying three-dimensional effects is fundamental for the identification of technical solutions that will help to reduce scours downstream of a stilling basin. The works analysed by means of a physical model are characterized by a marked asymmetry from both the geometric and the hydraulic point of view; as this asymmetry may give rise to random phenomena of stream flow concentration, it can lead to the anomalous working of the stilling basin as well as deep scours in the mobile river bed. This erosion is reproduced in the model and the experimental study has led to variations in the design of the stilling basin that, through the elimination of concentration and asymmetry in the stream flow, have resulted in a drastic reduction in scours.”

Keywords: stilling basin, local scours, mobile river bed, experimental tests.