Zujevina River in Sarajevo Canton
The Sarajevo Canton is located in the Dinaric Mountains, at the contact of two large natural-geographical entities; Danube and Adriatic Sea.
In terms of traffic and geography, this position is of particular importance, intersected by vital communication links, such as north-south direction.
In this direction, which goes along the valleys of the Bosnia and Neretva Rivers, Sarajevo Canton is connected to the Central European and Mediterranean macro regions. The Canton of Sarajevo is connected with Western Europe by the valleys of the Lašva and Vrbas rivers, and the valleys of the Miljacka and Prača rivers with Eastern Europe.
The total area of Sarajevo Canton is 1276.9 km2, which is 2.5% of the total area of Bosnia and Herzegovina.
The territory of the Sarajevo Canton covers the areas of the municipalities of Centar Sarajevo, Hadžići, Ilidža, Ilijaš, Novi Grad Sarajevo, Novo Sarajevo, Stari Grad Sarajevo, Trnovo and Vogošća.
Sarajevo Canton relief is predominantly mountainous. From the geomorphological point of view, Sarajevo Canton is a distinct mountain area where 78% of the area is in the area above 700 m above sea level, 13% in the hilly region from 550 to 700 m above sea level, while only 9% of the territory belongs to the lowland region below 550 m above sea level. The altitude difference in the Sarajevo Canton ranges from the lowest point of 423 m above sea level (Bosnia River valley near Lješevo) to 2088 m above sea level on Treskavica Mountain.
Hydrological Characteristics of the area
The Sarajevo Canton area is very rich in water, mostly in the form of river flows and springs, and other hydrographic values such as lakes, springs and thermomineral springs are present. Also significant is the work of water, which creates special geomorphological and hydrographic phenomena such as waterfalls, canyons, etc.
Hydrographically, the Sarajevo Canton also includes a part of the watershed between the two main B&H catchment areas. The southern slopes of Bjelasnica and Treskavica belong to the basin of the Adriatic Sea (Rakitnica watercourse), while all other water phenomena (about 93.5% of the surface) gravitate towards the river Bosnia, including the rivers Željeznica, Dobrinja, Miljacka, Vogošća, Ljubin, Misoča, Stavnja and Zujevina and those they belong to the Black Sea river basin.
Most of the river network (about 80% of the surface of Sarajevo Canton) is surface watercourses, which extend in the northern, eastern, western and central areas. Some of the permanent watercourses in the Sarajevo Canton are; Bosnia, Railway, Zujevina, Miljacka, Ljubina, Misoča, Stavnja, Tilava, Dobrinja, Mošćanica, Vogošćanska River, Rakitnica and others.
Causes of floods in Sarajevo Canton
Analyzing the floods that have occurred in the Sarajevo Canton in the last ten years, it can be concluded that the most common causes of floods in the Sarajevo Canton are as follows:
– heavy and prolonged rainfall and sudden melting of snow which cause intensive inflow of large quantities of water into watercourses, which cannot fully accept them;
– torrential and mountainous waters of great destructive effect, which are formed after heavy local showers (large amounts of rain in a short period of time), resulting in the discharge of smaller watercourses and streams, which due to their unpredictable nature and strong currents can carry large quantities of trees, silt and other wastes which can cause extremely serious damage to the infrastructure and population of the affected area;
– high groundwater and surface water levels, poor drainage network in these areas, unregulated and unregulated channels for receiving and draining surface and groundwater;
– unregulated permanent regulation of watercourses on critical sections through larger settlements;
– uncleaned riverbeds of various waste materials, vegetation, spruces, silt and rocks, which all together reduce the flow profile of the watercourse, which ultimately leads to floods;
– insufficient dimensions of flow openings of a number of bridges and culverts;
– unplanned and illegal mass construction of structures on floodplains along watercourses;
– construction of roads on floodplains along watercourses;
– Undeveloped main and auxiliary defense embankments on critical sections of larger watercourses
– unplanned and uncontrolled deforestation in the catchment area of the watercourse, which affects the erosion of the surface layer of the soil and reduces its capacity to absorb larger quantities of water, resulting in faster flow of water into the watercourses, which creates the conditions for floods;
– Uncleaned canal and shafts for the uptake and discharge of atmospheric wastewater in urban urban areas, which, due to heavy local showers (heavy rainfall in a short period of time), cause the basement of residential and commercial buildings to flood, as well as the flooding of roads.
The area proposed for analysis within the FLORIS project is shown in the figures. This is the lower part of the basin, below the HS Blažuj. The upstream sections that pass through the populated part are generally regulated, except for this section. The river bed is neglected in this part, with insufficient capacity, so frequent flooding occurs.
Flood In Canton Sarajevo
Preliminary flood risk assessments have been completed for the BiH area, as well as CS, so far. According to the adopted Methodology for development of flood risk and hazard maps, all areas where floods of 1/100, 1 can be expected to be estimated 1/50 and 1/20 large waters, for the Sarajevo Canton area, (Through a preliminary flood risk assessment) (Figure 4).Figure 14 – Geometric data required for the hydraulic calculation prepared in the HEC-GeoRas application
Applying the defined methodology for flood zones, the significance of flooding was determined based on its flood index. There are ongoing activities on the development of hazard and risk of floods 1/100 in areas where it can be expected flood risk (AFA area-Area for Further Assessment)). The following section shows registered flood events in the Sarajevo Canton, on the first (I) category watercourses, and on their tributaries, ie second (II) category watercourses (Figure 5).
The value of the flood risk index (I) for defined flood polygons is determined within each polygon based on Corina. Summing up all the impacts within the polygons that floods have on human health, the environment, cultural and historical heritage and economic activities, a summary flood index was obtained. Also, for each floodplain of historical floods (from the categories of extremely significant, significant and medium significance) a “segment” is defined which contributes most to the values of the total index (eg flooded arable land, endangered buildings, flooded roads, endangered factories, monuments, etc.).
It is important to note that estimates of the flood lines for waters 1/500, 1/100 and 1/20 were made through PFRA for data obtained from topographic maps 1: 25000, 1: 10000, ortho photos, and geodetic images of small parts of the riverbed. Figures 4, 5, 6 and 7 are also taken from these documents and are a rough estimate of the flood zones.
Hydrological Analysis Of The Zujevina River
According to the latest processing on the digitized maps, the Zujevina catchment area is 176.4 km2 (Figure 8). Karst formations are pronounced in the upper, southern part of the basin, and it is difficult to define the boundary of the basin. Zujevina has a torrential character. Most of the water is from February to May due to the melting snow on the slopes of Bjelasnica, whose slopes drain.
The Zujevina River is the first left tributary of the Bosna River (Figure 9). Its length is about 40 km. In the upper and lower part, it flows to the east, and in the middle stream to the northeast. The mean perennial flow of Zujevina to the Blažuj HS is Qsr = 3.10 m3/s, with an orographic catchment area Fsl= 172 km2.
The area proposed for analysis within the FLORIS project is shown in Figure 10.
This is the lower part of the basin, below the HS Blažuj. The upstream sections that pass through the populated part are generally regulated, except for this section. The river bed is neglected in this part, with insufficient capacity, so frequent flooding occurs (see Photo 1).
Photo 1 View on the riverbed of the Zujevina River
A complete hydrological analysis for the HS Blažuj were done in 1982, with the series 1953-1979 Years. A new hydrological study for HS Blažuj was done in 2011 and covers the periods 1966-1990 and the period 2002-2009. There were no other treatments after this hydrological treatment. This report gives an overview of the results obtained in the 1982 hydrological study, as well as the results of a new hydrological study in 2011.
HD Model Of River Zujevina And Pilot Area
Through the FLORIS project, 1D unsteady flow and 2D unsteady flow of the Zujevina River (L=3600 m) were made in the area under consideration. Field data were obtained by LIDAR imaging. Using the HEC-GeoRAS 4.1 open source application. (US Army Corps of Engineers, 2003), used in combination with the GIS software package, refined digital terrain model and orthophoto images, the geometric data that was required for the hydraulic calculation in the Hec-Ras software package was prepared. On that occasion, the cross-sections were redefined where necessary. All changes outside and into the watercourse, left and right bank, and Manning’s roughness coefficient are defined.
For the calculation of flood lines in widespread use is a hydraulic program – the HEC-RAS model, which enables the calculation of 1D and 2D steady and unsteady flow in open watercourses (US Army Corps of Engineers, 2003). The hydraulic model requires a description of the river bed geometry, from plotting the watercourse layout to defining the points of individual transverse profiles in local coordinate systems, describing the geometry of the watercourse and coastal space, determining the roughness coefficients of the riverbed, and other parameters that could affect hydraulic quantities in the watercourse.
At the location of geodetically or otherwise measured cross-profiles, where the spatial coordinates X, Y, Z are known, the geometry is sufficiently precise. When the DMT is made, files with more accurate geometric data of a wider space, required for calculations with the HEC-RAS hydraulic model, are prepared using HEC-GeoRAS in ArcGIS. If necessary, the prepared geometry in the HEC-RAS program can be supplemented by details, such as objects or other (biotechnical) construction in the space.
By entering the geometric data into the HEC-RAS (Figure 14) and the defined flows at the water meters, hydraulic analysis was started.
For more details on this case study area and simulation results, read the following documents: