Modelling of the Impact of the Retention Reservoir on the Flood Protection of the City – A Case Study for the City of Kalisz (Central Poland)

Abstract

Abstract Floods are natural phenomena related to the circulation of water in nature and they cannot be avoided. Despite the methods of predicting floods, technological development and civilization progress, the flood risk has been still increasing. The relevant hydrotechnical advancement, rational spatial development and optimal water management have a significant impact on reducing the consequences of flooding. Particularly retention reservoirs are decisive to rising flood safety and living conditions of urban residents who are at risk of flooding. The construction of a retention reservoir is a serious engineering, economic and eco-scale challenge. It must be preceded by numerous studies and analyses necessary to carry out the entire construction process and subsequent operation in an optimal way. At present, a number of engineering and environmental analyses are supported by the use of forecasting and computational tools based on the mathematical description of a given physical phenomenon. With their use, it is possible to determine, at the design level, the impact of a technical facility on various elements of the natural or the human environment. The paper presents the impact analyses of a planned retention reservoir located on the Prosna river in the flood protection system in Kalisz (Poland). The flood protection system is insufficient in Kalisz and its weakness was demonstrated, among others, by flood in May, 2010. Analyses were based on data received from the unsteady flow numerical modelling system and optimisation methods to support the management process of retention reservoir resources for extreme periods. The formulated task of dynamic optimisation due to its non-linearity was simplified to a static task by discretisation of an independent variable.