This paper presents an overview and synthesis of a large number of issues related to the contemporary development of hydro-information systems that are developed in the Institute for Development of Water Resources "Jaroslav Cerni" in order to meet the needs of management of the hydropower potential of Serbia. Hydro-information systems are designed to provide support to decision-making processes so they can provide significant information on different processes within a catchment on scenarios of future development with multiple variants, as well as on the system utilization in real-time. The most important goals of the development and application of such systems are the following: integration of all relevant hydrologic, meteorological, hydrogeologic, hydropower and other data, as well as the creation of the conditions for their availability to a wide circle of interested users, making of the best possible decisions related to operational management of hydropower plants in various situations, as well as making of the best possible strategic decisions in order to make the optimum choice of the solution for the integral basin management. This paper is based on such a concept so that the original contributions related to the subject topic are presented within a broader framework. At the beginning are presented certain general considerations related to planning and management of water resources, as well as the general role of hydropower plants within an integral electricity generation and transmission system. Further on, the reader is introduced to the application of information technologies in exploitation of water resources, with a particular stress on the role of simulation and optimization software in the management of hydropower systems. After this overview that describes broadly, but precisely, the main notions, the paper presents the role and importance of hydropower plants within the electricity generation and transmission system of Serbia, including a short overview of the possible further development of electricity generation capacities. The central part of the paper presents the concepts and structures of hydro-information systems (which consist of the following sub-systems: central server, acquisition servers and user sub-systems, which include the user server and specialized HIS applications). Three main hydro-information systems in Serbia are specifically outlined and described in detail; they are being continuously developed in all aspects in accordance with the presented concepts and structures. These systems are: "Iron Gate" Hydro-Information System (related to the system of hydropower plants built on the common Serbian-Romanian section of River Danube; Serbian and Romanian hydropower plant "Iron Gate 1", with the total installed discharge of 9800 m(3)/s and the total installed power of 2165 MW, and Serbian and Romanian hydropower plant "Iron Gate 2", with the total installed discharge of 8500 m(3)/s and total installed power of 540 MW), "Drina" Hydro-Information System (which relates to the whole river Drina basin with an area of 19570 km(2), which is shared between the three neighboring states, so that 30.5% of its area belongs to Serbia, 31. 5% to Montenegro, and 37% to Bosniaand-Herzegovina; the system of 9 hydropower plants was built in the River Drina catchment and these plants have the total installed power of 1932 MW and average annual electricity generation of 6350 GWh; in this catchment it is possible to develop significant new hydropower capacities, which would allow for additional annual electricity generation higher than 7000 GWh), and "Vlasina" Hydro-Information System (which is related to the system of "Vlasinske HPPs" that has a relatively low power of 125.9 MW and the mean annual electricity generation of 295 GWH, but which represents a very important electricity generation plant within the system of EPS (Electric Power Industry of Serbia), because it is used for generation of peak-load electricity and as the cold or spinning reserve of the system). The presented hydro-information systems are actually the systems for the support to decision-making on all levels, i.e., local, regional, state and trans-boundary. These systems create possibilities for the optimum management in real time as well as harmonization of various interested parties (electric power industries, situated in different states, with different interests that operate under the circumstances of the evident lack of uniformity regarding natural inflows and consumption needs). In a long run the conditions are created for the further development on the catchment (new development projects, additional generation capacities etc.) in order to achieve the optimum exploitation of hydropower potential, as well as the multi-purpose use of water.
