engleski

Predicting output flood wave on the section of the Drava River

The movement of the flood wave along the river bed is a complex process, not only because of this that the flow varies in time, but because the water course hydraulic and geometric characteristics of the river bed is very variable. Propagation of water waves is the process that defines the characteristics of flood waves on a down stream section of the river flow on the basis of known flood waves in the upstream section. The main problem with the forecasts of flood wave output is in the mathematical description of the transformation input flood wave. The wave propagation can be illustrated by the space and time functions of discharge and depth. Flood routing is the determination of flow conditions in a river, given its initial state, the stream morphology and an inflow hydrograph. Flood- routing procedures may be classified as either hydrological or hydraulic. Hydrological methods use the principle of continuity and a relationship between discharge and the temporary storage of excess volumes of water during the flood period.Hydraulic methods of routing involve the numerical solutions of either the convective diffusion equations or the one–dimensional Saint–Venant equations of gradually varied unsteady flow in open channels. An example of a simple hydrological flood-routing technique used in natural channels is the Muskingum flood- routing method. In this paper for predicting output flood wave on the section of the Drava River (in the lower reaches) two methods are applied: Muskingum methods and a modified Kalinin-Milyukov method. The Muskingum method belongs to the class of hydrologic routing methods. Hydrologic routing models involve only storage and flow rates of floodwater and aim to capture the wave dynamics through their parameters. The Kalinin and Milyukov method is especially appealing for flow routing, because both model parameters, the number of linear reservoirs in the series and the time constant (or storage coefficient of the linear storage-outflow relationship of each reservoir in the cascade) are related to the channel’s characteristics and hydraulic conditions.

Flood wave ; propagation ; Muskingum method ; Kalinin–Milyukov method ; Drava River

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