Abstract:The paper presents a method for the correction of low quality DEMs, based on aerial photographs, for use in 2D flood modeling. The proposed method was developed and tested on the example of the floodplain of the Warta River, which is the third biggest river in Poland. The correction of DEM is based on a series of a small number of measurements using GPS-RTK, which enable calculations of the global statistics like mean error (ME), root mean square error (RMSE) and standard deviation (SD). The impact of DEM accuracy was estimated by using a 2D numerical model. The calculated values of flow velocities, inundation area and volume of floodplain for each tested DEM were compared. The analyses indicate that, after the correction procedure, the predictions of corrected DEM based on poor quality data is in good quantitative and qualitative agreement with the referenced LIDAR DEM. The proposed method may be applied in the areas for which high resolution DEMs based on LIDAR data are not available.

This study compares four digital elevation models (DEMs), based on various data sources, to define polder retention capacities. Two commercial and two publically available, free of charge data sources were used. Commercial sources are DEMs based on aerial images and LIDAR (Light Detection and Ranging) data. Free data source DEMs generated are based on: SRTM (Shuttle Radar Topography Mission) and ASTER GDEM (ASTER Global Digital Elevation Model). In addition, the impact of the spatial resolution of the numerical terrain model on the calculated polder volume was evaluated. A DEM based on LIDAR data was used as the reference model and was supplemented with our own geodetic GPS (Global Positioning System) measurements. In flood modeling and management, including retention of river valleys and polders, it is necessary to properly estimate their capacity and the relation between capacity and water level. The study showed the impact of quantitative and qualitative data sources in determining the retention capacity of a polder.

Abstract. The article presents the results of validation of static calculations carried out for a monolithic rectangular tank with walls of trapezoidal cross-section. Static calculations were made with the use of software based on the finite element method (FEM) and the finite difference method (FDM) in terms of energy (including spatial static work of the tank). Validation of the results was conducted on a concrete tank model using an innovative measurement tool, i.e. a coordinate measuring arm with a touch probe.

This paper presents an analysis of the effectiveness of variants of the reconstruction of a polder, which is part of the flood protection system of a large urban agglomeration. The Golina polder, located in the floodplain of the Warta River, was selected as the case study. The multi-criteria decision support methods AHP and Fuzzy AHP were used to assess the effectiveness of individual variants. Information on the floods from 1997 and 2010, data on land cover, land development, nature and historical objects were used to estimate the value of the coefficients for the multi-criteria decision methods. It was shown that the planned deep modernization of the hydrotechnical infrastructure and the purchase of land in the polder area is less effective than maintaining the current state of development of the polder.

No abstract

Abstract. This paper presents simulations of water seepage within and under the embankment dam of Lake Kowalskie reservoir. The aim of the study was to compare seepage calculation results obtained using analytical and numerical methods. In April 1985, after the first filling of the reservoir to normal storage levels, water leaks was observed at the base of the escarpment, on the air side of the dam. In order to control seepage flow, drainage was performed and additional piezometers installed. To explain the causes of increased pressure in the aquifer under the dam in May 1985 a simplified calculation of filtration was performed. Now, on the basis of archived data from the Department of Hydraulic and Sanitary Engineering using 3D HYDRUS STANDARD software, the conditions of seepage under the dam have been recreated and re-calculated. Piezometric pressure was investigated in three variants of drainage, including drainage before and after modernization.

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.

Streszczenie. Analizowano straty filtracyjne wzdłuż około 80-kilometrowego odcinka rzeki, powstałe w wyniku spiętrzenia wody w rzece Warcie wywołanego zrzutami ze zbiornika retencyjnego Jeziorsko realizowanymi w celu zapewnienia przepływów niżówkowych (minimalnych) Warty. Przeanalizowano 12 hipotetycznych przebiegów fali w zależności od wielkości i czasu trwania zrzutu. Parametry określające właściwości filtracyjne podłoża wyznaczono na podstawie badań terenowych przeprowadzonych na terenie polderu Majdany, w przekroju znajdującym się w połowie analizowanego odcinka rzeki. Wyznaczono skumulowane wydatki filtracyjne, będące sumą strat, oraz chwilowe wydatki przez dno koryta rzeki. Straty porównano z objętościami zrzutów w poszczegól-nych symulacjach. Wykazano iż straty na rozpatrywanym odcinku nie są duże i sięgają maksymalnie 1,3% objętości zrzutu a udział procentowy maleje wraz ze zwiększaniem się wielkości zrzutu oraz czasem jego trwania. Rozwiązania uzyskano z wykorzystaniem MES zaimplementowanej w pakiecie oprogramowania komputerowego Hydrus, umożli-wiającego analizowanie zagadnień niestacjonarnych ze zmiennymi w czasie warunkami brzegowymi.Słowa kluczowe: filtracja z koryta rzeki, straty filtracyjne, MES, Hydrus, zmienne w czasie warunki brzegowe