engleski

Modeling of long-term sedimentation in the Osijek port basin

On Drava River’s rkm 14+110 closure dam was constructed across the upstream end of the old bendway that is being preserved for Osijek port basin. During high water conditions when water level rises part of flow is diverted from main channel over closure dam. Overtopping of dam consequently disrupts water and sediment regime in port Osijek basin. Aim of this paper is to determine long-term sediment yield that enters the port carried by the flow over dam and conditions under which it deposits, changing port’s morphology during the process. This process is analyzed thought 8-year period, from 2005 until 2013. Paper presents modelling method for calculation of layer thickness for suspended sediment deposited in port basin. Bed forming sediment is extracted from total sediment inflow in port basin using Reynolds number as common parameter in sediment rating curves for port basin and gauging profile. For each sediment fraction conditions of its deposition are determined based on particle fall velocity, transport velocity and water column depth. Hydraulic flow conditions are calculated from measured hydrograph using 1D computations. Since sediment rating curve doesn't depict reliable relationship corresponding to flow sediment regime is analyzed for three characteristic scenarios (mean, minimum and maximum) according to data. Results are given as longitudinal profile of volume for deposited suspended sediment and compared to measured change in bathymetry for set time period.

Closure dam ; bedload sediment ; sediment transport ; settling velocity

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