No abstract

A serious problem in recent years of waterworks praxis has appeared to be the one with growing necessity for surface water detention . Continuous growth of natural terrain coverage for building construction, industry, free time activities and transport reasons leads to a widening of the area of build surface and lack of natural terrain with a capability of natural rainfall water infiltration. This causes serious damage to the natural water cycle. In cases where rainfall water falls on natural terrain, most water soaks in the soil and becomes part of the subsoil water. Only about 20% of rainfall water comes to rivers or is carried to stormwater drainage. As a consequence of the continuous growth of building construction and urban development, the natural terrain is replaced by compact soil; for example, the roofs of industrial, residential, commercial or other buildings, road networks, car parks etc. When the rainfall water reaches these surfaces almost 80% of this water flows to the waste-water disposal system or rivers and only 20% soaks into the soil. This leads to ecological damage as floods, torrential rain, and the decline of subsoil water level, local soil dehydration and endangering of sensitive ecosystems. It is necessary to build and develop not only urban constructions but also the artificial regulation of water circulation in nature, which contribute to the maintenance of ecological stability of the chosen location.

In recent years, the growth of population and the diffusion of settlements over flood vulnerable areas have increased the impact of floods worldwide. Natural disasters such as floods have constituted a major problem in many countries worldwide. Floods have caused immense economic and social losses, mainly as a result of unplanned urbanization, uncontrolled population density and not strictly inspected construction by authorities. Flood damages that have arisen on watercourses and hydraulic structures on the territory of the Slovak Republic have been huge. The most affected area is the eastern part of Slovakia, where the most complex situation is in the Laborec, Topľa, Ondava, Torysa, Latorica and Hornád river basins in the recent years, mainly in 2010. This contribution presents flood risk assessment and management in these territories. Keywords: flood risk assessment, flood risk management, directive 2007/60/EC.

The study of hydrological risk assessment is performed with the goal to reduce impacts of droughts and floods. Drought is the most complex but least understood of all natural hazards. It is broadly defined as "severe water shortage". Floods cause huge but mainly material damages. Mentioned natural hazards cause loss of life, human and animal suffering and damage to economy and environment. The present study area is prone to extreme climate events such as drought and flood. The objective of this study was to investigate precipitation trends in the chosen climatic stations in Libya and Slovakia. Annual and monthly precipitation trends were detected by the Mann-Kendall statistical test. Significant negative trends of annual precipitation were found in four out of seventeen analyzed rainfall gauging stations in Libya. Significant positive trends of annual precipitation were found in six out of twenty analyzed rainfall gauging stations in Slovakia. November and August were observed to have decreasing trends in Libya and March in Slovakia. All other months displayed increasing trends in precipitation. The results show a trend towards drier conditions in Libya and an increase of moisture in Slovakia.

Environmental impact assessment (EIA) is a process with several important purposes, the principal of which is to be an aid to decision-making; providing decision-makers with a focused evaluation of the likely environmental consequences of sanctioning a proposed development action, before a decision is taken and at a time where it can actually affect the outcome. Risk analysis (RA) has become in recent years an important tool for decision-making and management activities. The objective of the paper is to propose a methodology for assessing water constructions, which will allow the assessment impact of water constructions on the environment and hence select the best option for the permission process. This methodology is intended to streamline the process of EIA of constructions in the field of water management. One of the paper's objectives is to create a system of EIA of water constructions through RA evaluation of options, the result of which should lead to the selection of future activity, quantified with minimum risk to the environment. Comparison options and the designation of the optimal variant will be implemented based on selected criteria which objectively describe the characteristic lines of the planned variants and their impact on the environment. The application of developed methodology for the process of EIA will develop assumptions for further improvements and, respectively, more effective implementation and performance of this process.