Preliminary Results of Hydrologic Reconstruction of the May 2014 Kolubara River Flood - page 02

Digital Terrain Model

The SRTM (Shuttle Radar Topography Mission) digital elevation model (DEM) was used for catchment and subcatchment delineation, as well as for estimation of topographic-based model parameters (flow length, channel slopes, etc.). The resolution of this DEM is 3 arc seconds in the geographic projection (WGS84 datum), which when reprojected to the official Serbian state projection (Transverse Mercator), equals approximately 90 x 60 m. This was further resampled to a 70 m grid in order to ensure square pixels, while preserving detail.

The raw SRTM DEM data are very limited for hydrologic application without specific surface area corrections (Wolf, et al. 2009), and a series of pre-processing steps (Zlatanović and Gavrić, 2013) were undertaken to obtain a "hydrologically correct" terrain model. Once the depressions and flat areas were treated, the flow directions and flow accumulations were determined using the Deterministic 8 Method (O'Callaghan and Mark 1984). The pre-processed digital elevation model is shown in Figure 1.

 

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Figure 1: SRTM Digital Elevation Model of the Kolubara River basin.

 

Hydrometeorological data

Hydrometeorological data used for the hydrologic model for the Kolubara River are official data of the Republic Hydrometeorological Service of Serbia (RHMSS). These are primarily data on precipitation and discharge obtained from official measuring stations. The data were registered in the flood period from May 12th to 24th, 2014.

Precipitation data:

  • Daily rainfall at the following pluviograph stations in the Kolubara River basin: Bogatić, Brežće, Donje Crniljevo, Donje Leskovice, Jagodići, Kaona, Koceljeva, Koštunići, Liplje, Ljig, Lukavac, Mionica, Mratišić, Osečenica, Pambukovac, Parcani, Poćuta, Radarski centar Valjevo, Rogačica, Rudovci, Šarbane, Sibnica, Sopot, Stepojevac, Struganik, Stubline, Ub, Velika Ivanča and Valjevska Kamenica.
  • Hourly rainfall data on the main meteorological and automatic rain gauges in the Kolubara River basin: Valjevo, Majinovići and Štavica.
  • Hourly rainfall data on the main meteorological stations in the immediate vicinity of the Kolubara River basin: Loznica, Beograd-Vračar, Sremska Mitrovica, Smederevska Palanka, Kragujevac and Požega.
  • Hourly discharge data from official hydrological stations in the Kolubara River basin: Belo Polje (Obnica), Sedlare (Jablanica), Valjevo (Kolubara), Degurić (Gradac), Mionica (Ribnica), Slovac (Kolubara), Bogovađa (Ljig), Beli Brod (Kolubara), Zeoke (Peštan), Koceljeva (Tamnava), Ćemanov most (Tamnava), Ub (Ub), Draževac (Kolubara).

Available data on flooded facilities were acquired for the following: open pit mines "Tamnava - West Field", "Tamnava - East Field", and "Veliki Crljeni". Available data on the status and functioning of flood protection facilities were collected for the reservoirs: "Stubo-Rovni", "Paljuvi Viš", and "Kladnica". Data on flooded settlements and damage to infrastructure were considered tentatively: the cities of Obrenovac (total volume of flood water) and Valjevo (size of the flood-affected area), towns of Koceljeva, Ub, Vreoci, Bogovađa, etc. (size of the flood-affected area), damage to embankments and railway lines (locations and extent of destroyed infrastructure).

 

Methodology

Decomposition of the Kolubara River Basin into Hydrological Elements

To develop the hydrological model of the Kolubara River, the basin was divided into subcatchments using the digital terrain model. The subcatchment outlets were selected based on the spatial configuration and hydrography of the basin, the locations of existing hydrological stations, flood protection structures, areas severely flooded in May 2014, and relevant locations for flood protection measures. In this way, the input, control and output profiles were defined.

The input profiles of the hydrologic model were defined as: reservoir Stubo-Rovni on the Jablanica River, hydrologic stations Belo Polje (Obnica River), Degurić (Gradac River), Mionica (Ribnica River), Bogovađa (Ljig River), Zeoke (Peštan River), Koceljeva (Tamnava River), and Ub (Ub River). The control profiles were defined as: hydrologic stations Sedlare (Jablanica River), Valjevo (Kolubara River), Slovac (Kolubara River), Beli Brod (Kolubara River), and Ćemanov Most (Tamnava River). The mouths of significant tributaries are: the Lepenica, Toplica, Vraničina, Kladnica, Lukavica, Turija, and Beljanica rivers. The locations of embankment breaches are: open-pit mines "Tamnava - West Field", "Tamnava - East Field", and "Veliki Crljeni", as well as left-bank embankments of the Kolubara and Tamnava rivers. The output profile for the hydrologic model is the hydrologic station Draževac on the Kolubara River.

The hydrologic model was divided into 26 subcatchments, 24 river reaches, 3 reservoirs, and 2 sinks (see Figure 2).

 

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Figure 2: Layout of the hydrologic model of the Kolubara River basin.