engleski

A Cfd Approach To Flood Forecasting In The Case Of The River Rjecina

This paper presents a CFD (computational fluid dynamics) approach applied in flood forecasting and prevention in the case of the lower part of the river Rjecina (Croatia, Europe).Rjecina is a torrential river, which in its lower part flows trough the city of Rijeka and into the Adriatic Sea. Key flood risk factors for the urban area surrounding the watercourse are possible sediment settlement, bridges that narrow the primary riverbed profiles, high tides etc. In order to design flood prevention measures acceptable in the urban environment a computer model was developed. This model is based on the 2D shallow water (i.e. St. Venant) equations. Since these equations are hyperbolic conservation laws with a significant source term, Q-schemes developed by Bermuddez, Dervieux et a1. were applied in the numerical computation. In this way the resulting computer application can simulate nonstationary river flow and flooding, dam breaks, supercritical flow, hydraulic jumps etc. First step in the application of this approach on the case of the lower part of the river Rjecina was digitaliztion of geodetic data and development of the numerical mesh. The model was then verified by comparison with measurements. In this paper some of the numerous simulation results are presented: concerning the possible sediment accumulation and concerning influence of the bridges. The main advantage of the developed computational model verified computational accuracy and the simplicity, with which hypothetical changes in the riverbed and surrounding urban area can be introduced. Obviously, the computer application can and will be applied to other flood prediction case studies.

mathematical model; Q-schemes; computer simulations; river estuary; flood forecasting and prevention

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