Institute for Development of Water Resources Jaroslav Černi and the Republc Hydrometeorological Service of Serbia carried out detailed processing and analysis of available hydrometeorological data within the amendments of the draft for Water Management Master Plan of Serbia in 2009. In this particular case, the most important characteristics of time series of hydrological and meteorological parameters on key sections of hydrological and meteorological stations, their conventional processing and analysis was completed and updated. The final goal of amendments of the draft of Water Management Master Plan is to provide elements to define the balance of available water resources in the territory of the Republic of Serbia, necessary for defining the strategy of water use and defining the conditions for integrated and rational management. This paper presents the most important elements of water balance using modern GIS technology.

Microbiological monitoring of river water quality is obligatory for use-related aspects such as drinking water production, irrigation and recreation. Assessment of the microbiological quality of water and sediment at the Velika Morava River was performed at five sites, during 2010 and 2011. By applying standard procedures for sanitary correctness and organic load assessment, total of 16 parameters were analyzed. Results of analysis indicated that microbiological water quality of the Velika Morava River is unsatisfactory.

The paper presents the results of preliminary study of the intestinal content in bream (Abramis brama L. 1758) of the Danube River through the Belgrade Region. The fishes were collected in May and October during the period 2007-2009 at two sampling sites along the course. A total of 42 fish specimens of different age (2+ to 6+) were examined. By examination of compositing of intestine of bream have been found members from macrozoobentho-groups – Oligochaeta, Gastropoda (Lithoglyphus naticoides), Bivalvia, Amphipoda (Gamaridae). Our investigation showed that the diet of bream is dependent of bottom fauna composition and structure.

In the spring/summer and autumn season of 2010 dynamics of macrozoobenthos structure of Moravica River was investigated after the changes in habitat caused by floods. It was found that macroinvertebrates are represented with 13 groups and 64 taxa from 54 genera. Trichoptera fauna was represented by 11 species, Diptera 10, 8 Ephemeroptera, Odonata 5, 6 Oligocheata, Gastropoda 5, Crustacea 3, 2 Hirudinea, Bivalvia 2 and Turbellaria 1. In average 11 taxa was identified in samples. Most abundant were Gammarus pulex fossarum, Grammarus balcanicus, Asellus aquaticus and Chironomus thumma. Abundance of macroinvertebrates at the downstream direction was increasing and was correlated with decreasing number of taxa especially in the spring season. Species are equal in number to the initial sites, and downstream a smaller number of species dominated. Average value of N-index was 2.1 which points to relatively favorable structure of macroinvertebrates. Average value of C of 0.32 indicates increased dominance of individual species. Saprobity index ranged from 1.6 to 3.5 at average of 2.3.

Physico-chemical and microbiological analysis of Brvenica River water was conducted in period 2006-2010 and showed seasonal variations of water quality. The results of correspondence analysis indicated that the year 2006 regarding the physical and chemical characteristics of water, was different from the rest of the examined period. This year was characterized by the absence of ammonia, low contents of nitrite, iron and chlorine, and increased concentrations of KMnO4 consumption. In 2007 and 2008 presence of manganese in water, low concentration of KMnO4 consumption was detected as well increased turbidity and electrical conductivity. And the third distinguish period are years 2009 and 2010 when water was characterized by low concentration of NO3, and the presence of ammonia, NO2, and iron in the water, while turbidity was low and conductivity was average. In Brvenica River water Escherichia coli, Citrobacter sp., Enterococcus sp., Klebsiella sp. are detected. In year 2006 number of aerobic bacteria and total coliforms were rather low, while their number in 2008 is relatively high. Over the whole period, only in 2008 fecal streptococci were not detected. Other years are characterized by growth of aerobic bacteria and total coliforms and the occasional presence of fecal streptococci. Throughout the whole examination period fecal coliform bacteria were present in the water.

This paper presents the results of the Danube River water quality analysis based on the calculated SWQI index values, using the data set provided by the Hydrometeorological service of the Republic of Serbia for the year 2009. The relevant parameters are sampled once a month on average, at 16, measuring stations of the River Danube along the flow through Serbia. Data grouped on the sampling site basis, averaged on a yearly level, resulting in a median SWQI for each sampling station, are employed to obtain a synthesized quality indicator. Research shows that the overall quality of the water of the Danube in Serbia, SWQI = 85 for the given one-year period and to match the descriptive indicator very good water quality.

The paper presents results of microbiological quality of three drinking water sources – Ratno ostrvo, Petrovaradinska ada and Strand. The following analyses were carried out in 2010: total count of aerobic mesophilic bacteria at 37 deg C, count of organotrophs (categorization according to Kohl), aerobic facultative organotrophs, lipolytic and hydrocarbon oxidizing bacteria. Organotrophic count was determined on low nutritive R2A medium. Enzymatic activity of water was also determined and water was categorized according to index of phosphatase activity (IFA).

This study was performed to investigate the influence of the ozonation process on natural organic matter (NOM) and trihalomethane, haloacetonitrile and chloropicrin precursors in groundwater. The largest reduction in dissolved organic carbon, DOC (up to 25%) and UV 254 values (up to 69%) was achieved using 3 mg O3/mg DOC. Reducing the total organic matter resulted in a reduction of trihalomethanes precursors to 194 micro g/L. On the other hand, when it comes to the precursors of the high priority nitrogenous disinfection by-products, the oxidation of NOM by ozone and the resulting increase in organic matter with a low molecular lead to an increase in the haloacetonitrile precursors compared to the raw water and the formation of chloropicrin precursors.

A contemporary biostability assessment of raw and treated water requires determination of biodegradable organic matter fraction responsible for bacterial growth. BDOC test allows monitoring of bacterial growth by assaying chemical changes in the test-water and thereby determine the content of biodegradable dissolved organic carbon (BDOC). The aim of this study was to optimize the required period for performance of BDOC tests, and to examine the use effectiveness of different biofilm carrier. The results indicate that the BDOC test with sand-inoculation is more effective compared to the anthracite, and recommendations for monitoring of biodegradation process are a period of 3-5 days.

The paper deals with determination of the economic elements of water management, which reflect the specific foundations, processes, principles and goals that are determined by the water policy. In terms of services, this represents the economic valorization of the foundations in manageable and unmanageable technical and natural systems, in which processes take place to bring water to a certain target quantity and quality, as well as provide safety against water in time and space. The use of, and protection against water, are under the pressures and influence of natural climatic and soil factors, the balance condition of surface and groundwater, and in particular human activities and demands for the characteristics of water in a water body, water area and in the river basin. These factors influence the demand for services, which also depends on the available domestic product, its volume of use, tastes and preferences. The offer consists of services for a particular quantity and quality of the available water, and for a certain degree of safety from the harmful effects of water, which are achieved by the employees of the functional facilities and systems. Together with the activities of the association, population and public services, the use of, and protection against water make up the totality of water management. It requires a decision process in all of the functions involved in planning, organization, management and control. Water management is identified with the water policy and activity, although there is a difference between them. The first is represented by a decision-making system in planning, organization, management and control, while the second is represented by the activity systems of government in the field of protection against water, as well as the protection and use of water. The activity consist of certain services which are performed by the employees of the companies, through the provision and performance of water management services in various time and space, in accordance with the offer and the demands of the users.