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EN
The study involves a preliminary analysis of short-duration high-intensity rainfall events in the area of Cracow. The events were selected from a 2-year data record from the MPWiK (Miejskie Przedsiębiorstwo Wodociągów i Kanalizacji [Municipal Water and Sewage Company]) in Cracow. A spatial analysis was carried out by comparing rainfall events with highest single totals which occurred at the same time at all observed precipitation stations. Extracted were nine cases from the data record of 2013 and ten from the data record of 2014. Each of the analysed events was classified according to the Chomicz scale for rainfall intensity in order to distinguish maximum rainfalls, in particular of the following types: heavy rainfalls, rainstorms and torrential rains. Additionally, observed were cases of the most unfavourable rainfall events, i.e. ones with the highest totals in the observed year. In both 2013 and 2014, certain areas in Cracow were observed to be characterised by a pattern of repeating rainfall types. Also, a change in the rainfall category was observed from lower into higher and reverse in certain areas represented by the same gauging stations. At the stations located in varying distances within one urban area of Cracow, the intensity of rainfall varied from rainstorm A1 to torrential rain B1.
EN
Urbanisation and climate change have significant impact on disturbing water balance in catchments. Uncontrolled urban development, increased land surface sealing, and increasingly appearing heavy rainfall cause local inundations called urban flooding. Rational catchment water management necessitate that a new approach to the problem of flooding be introduced that includes the human factor. Greater emphasis should be placed on local management of rainfall water within catchment, especially in urban areas. What is more, it is of utmost importance to provide efficient legal system and co-operation of various authorities and decision-makers in terms of urban land use management. The present article reviews different courses of actions taken in order to improve reasonable water management in the USA, Europe, and Poland in face of climate change and urbanization that cause flooding.
EN
This paper presents an approach to estimating the probability distribution of annual discharges Q based on rainfall-runoff modelling using multiple rainfall events. The approach is based on the prior knowledge about the probability distribution of annual maximum daily totals of rainfall P in a natural catchment, random disaggregation of the totals into hourly values, and rainfall-runoff modelling. The presented Multi-Event Simulation of Extreme Flood method (MESEF) combines design event method based on single-rainfall event modelling, and continuous simulation method used for estimating the maximum discharges of a given exceedance probability using rainfall-runoff models. In the paper, the flood quantiles were estimated using the MESEF method, and then compared to the flood quantiles estimated using classical statistical method based on observed data.
4
Content available remote Wpływ uszczelnienia powierzchni zlewni na odpływ wód deszczowych
PL
Tereny naturalne często zamieniane są na powierzchnie utwardzone czy uszczelnione. Stopień uszczelnienia powierzchni oraz infrastruktura komunikacyjna i hydrotechniczna w znacznym stopniu wpływają na zmianę relacji opad–odpływ na danym obszarze. Wszystkie te czynniki pociągają za sobą konsekwencje, których skutkiem często są liczne i gwałtowne powodzie. W artykule dokonano oceny wpływu rodzaju powierzchni na wielkość odpływu wód deszczowych z obszaru naturalnego i zurbanizowanego oraz wpływu uszczelnienia terenu na hydrogramy odpływu.
EN
Natural areas are often converted into paved or sealed surfaces. The degree of surface sealing, public transport and hydrotechnical infrastructure significantly alter the rainfall-runoff relationship in the area. All these factors entail consequences which often result in numerous and severe floods. The paper assesses the impact of surface conditions on the size of storm water runoff from both natural and urban area and the impact of seals on land runoff hydrographs.
PL
Korzystając z map topograficznych w małej skali, należy zawsze uwzględniać fakt, że są one mapami niedokładnymi, a parametry wyznaczone na ich podstawie mogą być obarczone dużymi błędami. Niniejszy artykuł pozwala na analizę wielkości różnic występujących przy wyznaczaniu hydrogramów odpływu w zlewniach niekontrolowanych, uzależnionych od parametrów hydrograficznych zlewni, wyznaczonych na bazie map topograficznych w skali 1:50 000.
EN
In using small-scale topographic maps, we always have to bear in mind their inaccuracy, and that the parameters estimated on their basis may be burdened with significant differences. The following work allows for an analysis of error size occurring when estimating runoff hydrographs for uncontrolled catchments that are dependent on catchment hydrograph parameters, estimated based on topographic maps in 1:50 000 scale.
6
Content available remote Obecny stan monitoringu zjawiska suszy w Polsce i na świecie
PL
Na bazie zebranych materiałów dokonano przeglądu obecnego stanu monitoringu zjawiska suszy w Polsce i na świecie. Stwierdzono, że monitoring zjawiska suszy stosowany jest przez wiele różnych ośrodków, wykorzystujących często do oceny jej intensywności te same wskaźniki i metody. Niestety, pomiędzy tymi ośrodkami brakuje wymiany informacji dotyczacych wyników badań. Pocieszający jest jednak fakt, że stan monitoringu suszy w Polsce i na świecie poprawił się znacznie po silnej suszy z 2003 r. i wciąż wprowadzane są nowe metody, umożliwiające dokładną prognozę tego zjawiska.
EN
A survey has been carried out on the basis of the compiled materials. It concerned the current condition of drought monitoring in Poland and all over the world. It was stated that the drought monitoring was used by many different research centres which applied the same indicators and methods in order to estimate the drought intensity. Unfortunately, there is lack of information exchange concerning the research results between the centres. However, the condition of the drought monitoring in Poland as well as in the world has improved significantly after the intense drought of 2003 and still there are new methods being introduced, enabling more accurate phenomenon forecast.
PL
Na bazie danych rocznych przepływów maksymalnych niektórych rzek Polski dokonano porównania górnych kwantyli p% obliczonych tradycyjną metodą parametryczną (rozkład Pearsona III typu) i nieparametryczną metodą jądrową. (z asymetrycznym jądrem gamma K[GAM1]. W połowie przypadków metoda nieparametryczna wykazuje wielomodalny charakter rozkładu. Obliczone nieparametryczne kwantyle p[1%] i p[0,5%] w większości przypadków są wyższe od swoich parametrycznych odpowiedników.
EN
Based on yearly maximum discharge series on some rivers in Poland, a comparison of parametric upper quantiles (Pearson III type) and nonparametric (with the gamma kernel) method of probability distribution estimation was made. In half cases, the nonparametric approach showed multimodality of yearly flow distribution. It was also found that the calculated nonparametric upper 1% and 0,5% quantiles were in most causes higher that their parametric counterparts.
PL
Korzystając z rzeczywistych danych rocznych przepływów maksymalnych niektórych rzek Polski, dokonano porównania nieparametrycznej (z jądrem Gaussa) i parametrycznej metody estymacji funkcji rozkładu prawdopodobieństwa (rozkład Pearsona, typ III). W większości przypadków metoda nieparametryczna daje dwumodalny obraz rozkładu. Obliczone "nieparametryczne" kwantyle rzędu 1% i 0,5% są na ogół wyższe od swoich "parametrycznych" odpowiedników.
EN
Using yearly maximum discharge series on main rivers in Poland, a comparison was made of nonparametric (with the gaussian kernel) and parametric (Pearson III type) method of probability distribution estimation. In most cases, the nonparametric approach showed bimodality of yearly flow distribution. It was also found that the calculated nonparametric upper 1% and 0,5% ąuantiles were in general higher that their parametric counterparts.
EN
Identification of probability distributions of minimum discharges at fifty cross-sections on Polish rivers is presented in this paper. Three distributions: log-normal, Pearson type III and Weibul were taken into consideration. Their parameters were estimated by two methods: method of moments and the maximum likelihood method. Initial verification was achieved by the [lambda] Kolmogorov-Smirnov goodness-of-fit test. Selection of the best distribution was made based on the maximum log-likelihood value principle. The results were illustrated on the map of Poland. They showed that certain homogeneous areas of distributions appeared. The area of the upper Vistula river basin, middle and lower Odra basin and middle Warta and Noteć rivers are dominated by the Pearson type III distribution. Log-normal distribution prevails on the Bug river and its tributaries, lower Warta and lower Vistula rivers, while the Weibull distribution can be found both in the south and in the north of Poland. However, it should be stressed that the results obtained do not give basis good enough for more general conclusions and practical applications and further extensive research is required.
EN
Identification of probability distributions of maximum discharges at fifty cross-sections on Polish rivers is presented in the paper. Three distributions: log-normal, Pearson type III and Gumbel were taken into consideration. Their parameters were estimated by two methods: method of moments and maximum likelihood method. Traditional Kolmogorov-Smirnov goodness-of-fit test did not reject any of the proposed distributions, independently of estimation method. The modified Kolmogorov-Smirnov goodness-of-fit rejected only a few distributions. It appears that it is not much sharper. In this case two-sted selection was assumed. First of all method of moments was accepted, because it is more sensitive (in the range of high values) than the maximum likelihood method. Next that distribution was selected (from among the existing candidates) whose test statistic λ had the least value. The results were illustrated on the map of Poland. It turned out that certain homogeneous areas of distributions appeared. The area of the Vistula river basin except its downstream part is dominated by log-normal distribution while Gamma distribution prevails on the Oder basin and northern part of the country. This conclusion is encouraging, not enough however to be the base of further generalizations and resulting applications. However, it does not give good enough basis for more general conclusions and practical application.
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