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Analysis of extreme flow uncertainty impact on size of flood hazard zones for the Wronki gauge station in the Warta river

Dysarz Tomasz, Wicher-Dysarz Joanna, Sojka Mariusz, Jaskuła Joanna

Acta Geophysica

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2019

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Vol. 67, no. 2

661--676

EN

In this paper, the impact of maximum flow uncertainty on flood hazard zone is analyzed. Two factors are taken into account: (1) the method for determination of maximum flows and (2) the limited length of the data series available for calculations. The importance of this problem is a consequence of the implementation of the EU Flood Directive in all EU member states. The factors mentioned seem to be among the most important elements responsible for potential uncertainty and inaccuracy of the developed flood hazard maps. Two methods are analyzed, namely the quantiles method and the maximum likelihood method. The maximum flows are estimated for the Wronki gauge station located in the reach of the Warta river. This simple river system is located in the central part of Poland. The length of the available data is 44 years. Hence, the series of the lengths 40, 30 and 20 years are tested and compared with reference calculations for 44 years. The hydrodynamic model HECRAS is used to calculate water surface profiles in steady state flow. The Python scripting language is applied for automation of HEC-RAS calculations and processing of final results in the form of inundation maps. The number of trials for each factor is not huge to keep the presented methodology useful in practice. The chosen measure of uncertainty is the range of variability for maximum flow values as well as inundation areas. The estimated values stressed the great importance of the factors analyzed for the uncertainty of the maximum flows as well as inundation areas. The impact of the data series length on the maximum flows is straightforward; a shorter data series gives a wider range of variability. However, the dependencies between other factors are more complex. Hence, the application of methodology based on the simulation and GIS data processing for assessment of this problem seems to be quite a good approach.

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Lokalne problemy powodzi roztopowych na przykładzie zlewni Bolszewki

Wójcik E., Szpakowski W.

Gospodarka Wodna

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2016

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Nr 1

19--24

PL

Opracowywane w ramach wdrażania Dyrektywy Powodziowej mapy zagrożenia powodziowego nie obejmują, co wynika z przyjętej metodyki ich przygotowania, wszystkich obszarów narażonych na występowanie powodzi. W artykule omówiono jeden z takich przypadków odnoszący się do powodzi roztopowej o lokalnym zasięgu. Wykorzystując materiały archiwalne Autorzy omówili przebieg i skutki tego zjawiska, wskazując na naturalne i antropogeniczne przyczyny jego wystąpienia na przykładzie zlewni Bolszewki.

EN

The flood hazard maps, elaborated as part of implementation of the Flood Directive, do not cover all the areas exposed to the flood risk, as it results from the adopted methodology of their preparation. The article discusses one of such cases, related to a local meltwater flood. Based on archival documents, the Authors describe the course and the consequences of this phenomenon, using the example of the Bolszewki catchment basin, indicating the natural and the anthropogenic causes of its occurrence.

3

Mapy zagrożenia powodziowego i mapy ryzyka powodziowego a dyrektywa powodziowa

Kurczyński Z.

Archiwum Fotogrametrii, Kartografii i Teledetekcji

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2012

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Vol. 23

209--217

PL

W 2007 roku weszła w życie tzw. Dyrektywa Powodziowa nakładająca obowiązek opracowania map zagrożenia i map ryzyka powodziowego do końca 2013 roku. Metodykę opracowania takich map w Polsce określa Rozporządzenie Ministra Środowiska, Ministra Infrastruktury oraz Ministra Spraw Wewnętrznych i Administracji w sprawie opracowania map zagrożenia powodziowego oraz map ryzyka powodziowego. Mapy takie opierają się na aktualnych danych geodezyjnych i kartograficznych, a wśród nich na precyzyjnym numerycznym modelu terenu opracowanym z danych lotniczego skaningu laserowego. Powstał „Projekt Informatyczny System Osłony Kraju przed nadzwyczajnymi zagrożeniami”, określany skrótem ISOK, w ramach którego GUGiK przygotowuje takie dane. Artykuł przybliża metodykę opracowania map oraz zakres Projektu ISOK i poddaje analizie przyjęte założenia techniczne.

EN

In 2007 came into force so called Floods Directive imposing an obligation to draw up hazard maps and flood risk maps by the end of 2013. Methodology of developing such maps in Poland determines the Decree of the Minister of the Environment, the Minister for Infrastructure and Minister of the Interior and Administration on the development of flood hazard maps and flood risk maps. Methodology defines, among others, content range of maps, the quality of source data and the timetable for their implementation and publication. Such maps are based on current geodetic and cartographic data, including the precise digital terrain model developed from airborne laser scanning data. The project was created, "The Computer System of the National Guards against exceptional risks", abbreviated ISOK under which GUGiK is preparing such data. The territorial scope of the development includes more than 60% of the country threatened by floods. Work on developing the digital terrain model runs until the end of 2013. As part of the Project, in addition to digital terrain model, digital high resolution orthophotomap for more than 200 cities with 0.10 m terrain pixel size, and elements of Data Base of Topographic Objects will be produced. The article introduces a methodology of development of flood maps, the scope of the ISOK Project and examines the technical assumptions.