Author(s)

M. Santos & J. Hipólito

Abstract

The impact of tides on the flow of tidal rivers may constitute a very important subject under many aspects. Among those one can cite local erosions near fluvial structures and flood events in rivers. Nevertheless, the existent bibliography rarely approaches this type of flow, especially the analysis of the discharge in river sections influenced by the tide effects. To achieve this knowledge, a computational model to simulate one-dimensional unsteady flows in rivers and to analyse the impact of tides in the flow of tidal rivers was developed. The computational model supported by the complete 1-D Saint-Venant equations was implemented using the implicit Preissmann finite-difference method. The model was applied to a reach of the Sado River, which is a Portuguese river in which the fluvial flows effect the tide influence and during flood events have caused important damage in the neighbourhood. This application showed that the tide may represent an important disturbance factor in relation to the flood wave propagation. It is also important to refer to the two water stages rating curve analysis that was done on the last section of the above mentioned river reach, from which very good results were obtained. Keywords: unsteady flows in rivers, floods, tides, implicit Preissmann finite-difference method, 1-D computational model, rating curve. 1 Introduction The whole of the processes integrated in the hydrological cycle in which the water is subjected, from the precipitation to the flow, has been the matter of many research works that led to a more deepened knowledge of those processes.

Keywords

unsteady flows in rivers, floods, tides, implicit Preissmann finite-difference method, 1-D computational model, rating curve.