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The river basins and water management systems are characterized by a high degree of complexity. In order to find the best operation rules of the reservoirs during floods all other time consuming data processing (like flood wave propagation) should be simplified at maximum. For this purpose, the Genetic Programming (GP) approach was used. The GP transfer functions derived for flood propagation provide an excellent agreement with the floods propagation based on Saint Venant equations, but without time and other resources consuming. The synthetic floods of the ungauged tributaries keeping the same probability of exceedance along the main river were derived using regionalization studies. The proposed approach was tested for Sitna and Miletin river, two main tributaries of Jijia river.

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Droughts are natural disasters with a significant impact on the economy and social life. Prolonged droughts can cause even more damage than floods. The novelty of this work lies in the definition of a synthetic drought hydrograph (SDH) which can be derived at each gaging station of a river network. Based on drought hydrographs (DHs) recorded for a selected gaging station, the SDH is statistically characterized and provides valuable information to water managers regarding available water resources during the drought period. The following parameters of the registered drought hydrograph (DH) are proposed: minimum drought discharge QDmin, drought duration DD  and deficit volume VD. All these parameters depend on the drought threshold QT, which is chosen based on either pure hydrological considerations or on socio-economic consequences. For the same statistical parameters of the drought, different shapes of the synthetic drought hydrograph (SDH) can be considered. In addition, the SDH varies according to the probabilities of exceedance of the minimum drought discharge and deficit volume.

On the lower Danube (downstream Iron Gates) the river banks on the Romanian side are protected by dykes on a length of 1100 km. Different towns along the Danube River, like Giurgiu, Oltenita, Calarasi, Braila and Galati are still threatened by floods close to or higher than 1% probability of exceedance. The floodplain is divided by transverse dykes into enclosures, which could be used as lateral reservoirs (polders) for storing water and decreasing downstream water level during high floods.A Decision Support System (DSS) was developed by UTCB in order to evaluate the hydraulic consequences (water level, maximum discharge) for different scenarios of accidental or deliberate flooding of enclosures. A special sub-model for breach development (breach elevation and length evolution) was set up. Since the hydraulic simulations are time and other resources consuming, a hydrological model for flood propagation was used. After parameters calibration and validation based on registered exceptional floods in 2006 and 2010, different scenarios of enclosures inundation were tested. FLOOD RISK MANAGEMENT STRATEGIESDue to the increasing severity of the floods across Europe, the European Union issued the Flood Directive 2007/60/EC on the assessment and management of flood risk [15], which came into force on November 2007. According to the Flood Directive 'flood risk' means the combination of the probability of a flood event and of the potential adverse consequences for human health, the environment, cultural heritage and economic activity associated with a flood event.The strategies for flood risk management are based on structural and non-structural measures [6]. A basic degree of security against floods is obtained with hydraulic works (dams, dikes, diversion, etc.), which represent structural measures, while higher degrees of security are the result of the complementary use of structural and non-structural measures.Structural measures represent the expression of the "culture of reaction" against catastrophic events. Their purpose is the maximum reduction of flooding probability through hydraulic works. Non-structural measures can be divided into: a) preparedness measures that aim to reduce the flood vulnerability of socio-economic and environmental objectives; b) response measures, which are applied during flood genesis and after water withdrawal in the riverbed.The preparedness measures consist among others in planning and management of land use within the flood plain area, which is considered the most effective method for reducing vulnerability and increasing resilience to natural hazards [3], setting up or improving real-time information systems of data acquisition, hydrological warning and forecasting, as well as decision / alert systems, reconsidering the operational rules of the hydraulic works [12].A large number of mathematical models were elaborated for the operation of single reservoirs or for a cascade or reservoirs, from the use of linear programming, dynamic programming [1] and graph theory [11], to optimal tree-b...