Flood Modelling and the August 2002 Flood in the Czech Republic

In August 2002, disastrous flood came to the Bohemia in the Czech republic and heavily hit all main rivers and cities located on those rivers. Return period of August 2002 flood exceeded 800 year in some cases and the flood itself was the highest observed flood ever in most of the cities. This flood touched also Czech biggest and capital city Prague. Thanks to the hydroinformatics tools applied during flood situation, valuable information and knowledge regarding flood propagation and flood extend was available in advance. The chapter is dealing with applications of detailed mathematical models focused on determination of flow characteristics (water levels, water depths and velocity distribution) during statistically generated floods as well as real flood events. These results are used in the next step for delimitation of flood zones and allow an analysis of necessary flood protection measures in the whole river basin. This helps to solve problems of continuing urbanisation and economic growth in the areas exposed to floods, associated with further increase of population and related danger of potential economic and cultural damages. It is necessary to designate these areas as flood plain areas or areas exposed to special floods and to regulate adequately their use. This task is impossible to fulfil without strong and well-tested hydroinformatics tools as Digital Terrain Model DTM, hydrodynamic models and Geographic Information System GIS tools. The article concentrates on different approaches (1D and 2D) and different applications of mathematical models as supporting tools for decision makers on field of flood risks and flood protection in Czech republic, approved by real catastrophic flood situation