Estudio experimental y teórico del balance energético y el comportamiento del transporte sólido en una derivación lateral a 90 grados

Abstract

River diversions are not so common in nature and its presence are found in deltaic zones, nevertheless man made diversion is found in lateral channels for irrigation and hydroelectric purposes. In this paper a 90 degree diversion was built in the laboratory to understand the behaviour of the flow and the sediment transport in the diversion zone in which a 3D flow pattern is presented. In 1926 the Bulle doctoral thesis shows how the sediment discharge present in the derivation branch take a high percentage of the sediment discharge respect to the main channel. In the present paper it is offered a set of long term experiments that confirms the Bulle hypothesis. Also it is presented the vortex flow patterns that appear in the diversion zone, in which one of them is capable to deviate to the lateral branch almost all the sediment that flows into main channel. This horizontal axe vortex is responsible of the observations made by Bulle and the experiments are shown in the present document. The vortex affects more than the 90% of the width of the main channel, creating a barrier for the sediment that flows as bed load and suspension load. Nevertheless this hydrodynamic barrier is presented only for some flux momentum ratio between that evaluated in the lateral branch respect to that evaluated in the main channel. The energy necessary to maintain the vortex active is taking from the water flow income. This loose of energy is presented in the laboratory data and is explained with the energy balance equation. With only the 20% to 30% of water discharge into the lateral branch the vortex deviate at least the 90% of the sediment.