The hydropower potential in the Republic of Serbia, as the most important renewable energy source, has been estimated at around 17000 GW•h per year, where approximately 2000 GW•h could be obtained from small hydropower plants (SHP). Small hydropower plants in Serbia currently produce 150 GW•h. Accordingly, the share of the electricity production from small hydropower plants in the total electricity production in Serbia is too small. The paper presents a model for the selection of optimal locations for small hydropower plants, which includes an ecological criterion, along with technical and economic criteria. The ecological criterion is eliminatory, i.e. those parts of the watercourse that border on or pass through protected natural assets are not taken into account when considering potential optimal locations for SHPs. All technical and economic criteria are included in the calculation of the weighted arithmetic mean with the aim of determining the optimal position for the construction of small hydropower plants. The model is implemented in the SHPOP software and its application is demonstrated on five watercourses in Southeastern Serbia.

This research analyzes the peaks-over-threshold (POT) method for designed flood estimation needed to plan river levees, spillways and water facilities. In this study, a one-parameter exponential probability distribution has been modified by including the coefficient of λ, which represents an average number of floods and enables return period calculation within the specified period of time. The study also compares results using the Log-Pearson Type III distribution of maximum annual flows and a standard exponential distribution of the selected peaks over the threshold level. The aforementioned approach represents the standard mathematical tools for river flood design, while the proposed modification of the exponential distribution highlights the estimation of flood quantiles with longer return periods (e.g., 100, 1000 and 10,000 years). Moreover, the sensitivity analysis of the threshold selection is proposed to assist in the flood design flow estimation alongside the proposed modification of the exponential probability distribution. The study was carried out at the Danube River, and the Novi Sad hydrological station (Republic of Serbia) was used for the long-term recorded period from 1876 to 2015. The results suggest that the POT method derives more reliable estimates of design floods than the traditional statistical tools for flood estimation. The results suggest the theoretical values of the water level of the 10,000 years return period is equal to 867 cm, while the Log-Pearson Type III distribution of annual maximum flows underestimated this value for 14 cm.

Na primeru izgradnje jedne pristupne saobraćajnice prikazan je izbor optimalne vearijante gradjevinske mehanizacije za izvođenje zemlljanih radova. Izbor imedju mogućih varijanti je izvršem metodom višekriterijumske optimizavije Promethee. Vrednovanje varijanti je izvršeno preko više kriterijuma (broj mašina, cena, vreme, rezerva mašina, praktični učinak, broj radnika, cena efektivnog radnog sata.), pri čemu je razmatran uticaj svakog kriterijuma na konačno rangiranje alternativa. Upoređivanjem dva scenarija (sa različitim relativnim težinama kriterijuma) u modelu višekriterijumske optimizacije određeno je optimalno rešenje.U radu su izneti zaključci o uticaju pojedinih kriterijuma na konačno rangiranje alternativa.

The objective of this research was to determine the probability of road overtopping occurrence for a road culvert caused by surface runoff from the upstream catchment. A hydrological–hydraulic model was used for the development of an algorithm for road culvert maintenance based on the overtopping occurrence probability (CMOOP algorithm) for small mountain catchments. The hydrological model defines the regression dependence between the runoff hydrograph peak values and the probability of occurrences, whereas the hydraulic model calculates the culvert flow capacity by including in the calculation the level of sediment that culvert is filled with. The relationship between occurrences of overtopping and peak runoff value was defined using the runoff hydrograph transformation model in the accumulation on the upstream side of the road. In addition to the calculation of overtopping occurrence probability for the existing culvert condition, the CMOOP algorithm was used to analyze the impact of rehabilitation and reconstruction works from the perspective of legally based safety criterion for road overtopping occurrence probability (SCROOP). The CMOOP algorithm was appled to 67 concrete culverts located in a mountain road section in the Republic of Serbia. The results show that the application of rehabilitation works on selected culverts will increase the percentage of culverts that satisfy SCROOP from 49.25% to 89.55%, which confirms that the accumulated stone sediment is the main reason for the SCROOP unfulfillment.

The paper presents the application of cement stabilization in the world and in our country. In addition to the literature review, basic physical - mechanical tests of the pavement base without the use of hydraulic binder and with the use of hydraulic binder with different percentages of participation (3, 5, and 7%) were given. The hydraulic binder of the manufacturer LaFarge HRB 12.5 was used as a binder, and the material on which this binder was tested is a clay material taken from Subotica. Using this binder, it was concluded that any percentage of binder leads to significant improvement of the placenta and thus improves the load-bearing capacity of the pavement structure.