Increasingly, and often mutually conflicting requirements for the use of water resources, there is a need for more complex management methods, including the management of the volume of reservoirs. Silt filling of reservoirs is one of the most well-known problems of river hydraulics. Dams and reservoirs, created by damming river flows, cause the retention of river sediment (drag and floating sediment) that comes from the gravitating basins, or sub-basins of the reservoir's tributaries. By analyzing the sediment transport on the tributaries, and the total amount of sediment deposited in the Modrac multi-purpose reservoir, real data are obtained on the amount of sediment introduced into the Modrac multi-pupose reservoir, the dynamics of sediment input, and the degree of pollution of this type of water body. The Modrac multi-purpose reservoir is the only available water resource in the region of Tuzla and its surroundings. Acknowledging the fact that the useful volume of the reservoir is limited, and that over time the reservoir is filled with dragged sediment and coal dust as floating sediment, and that consumers - the population, industry and others must be provided with a water supply with a high degree of safety. Excess water needs to be used to the maximum for the purpose of electricity production, and there is a need to optimize the system, i.e. more efficient management of the water resources of the reservoir, i.e. to prove the maximum utilization of the reservoir while continuously providing all the necessary amounts of water to which the Modrac multi-purpose reservoir is connected.

Mufid Tokić1 Anadel Galamić2 Jasmin Hrnjadović3 Omer Kovčić4 UDK: 556.1:627.81 DOI: 10.14415/konferencijaGFS2019.072 Summary: According to the available existing documentation and various previous studies, the flow of water into the "Modrac" accumulation is not defined directly, by measuring the flows on the main creek Spreca and Turija, but indirectly, over the level and volume of the accumulation, as well as data on the discharge of water from the reservoir. In this way, a series of average daily values of inflow into accumulation was obtained for the period from 1980 to 2012. year. Interpretation of these data was done in the form of variation of annual inflows in the observed period, as well as average flow curve curves. By reviewing the previous measurements and surveys, it can be concluded that there is a more pronounced cyclicality of inflows over a longer period of time, with driers of dry and rainy periods. On the other hand, having in mind the natural correlation between the inflow of water and the spread of the deposit, it is logical to hypothesize that at the time of the hydrological maximum, the input is higher in the accumulation. Another important indicator of the hydrological regime of the lake is the duration of the inflow into the accumulation "Modrac". This curve points to the vast hydrological regime of the watercourse in the basin of the reservoir. In this regard, it should be noted that all watercourses in Bosnia and Herzegovina and the region, with a basin area of up to 1000 km2, have such a regime. Bearing in mind the similarity of physical and geographical conditions in the region, this analogy is quite logical. The hectic hydrological regime is characterized by a short duration of large waters and a very long duration of small water, as well as a large flow range (Qmax / Qmin).

Jasmin Hrnjadović1 Anadel Galamić2 Mufid Tokić3 UDK: 519.6:628.1 DOI: 10.14415/konferencijaGFS2019.074 Summary: The water supply system is a planned and meaningfully connected set of facilities and activities aimed at ensuring sufficient quantity of water in the most economical way. Defining the functional dependence of the hydraulic parameters of the water supply system is crucial because it enables the calculation of unknown values based on the appropriate available or measurable values. „Spline“ interpolation is one of the methods by which it is possible approximately, but with sufficient accuracy, to define the functional dependence of hydraulic parameters if we have known values at certain characteristic intervals that can be measured or calculated by one of the numerical methods. "Spline" interpolation denotes the method of constructing a function within the range of a discrete set, which approximates the already known points. The result is a function, or set of functions, by which it is possible to calculate the value of an unknown function for any value of the variable at a defined interval. The specific application of this method will be shown on the example in this paper.