Determination of theoretical flood waves, commonly known as hypothetical waves, is still a difficult problem to be solved. Most frequently hydrological modelling is used for this purpose. However, there are no methods for verifying the obtained calculation results. The assumption applied, that daily precipitation with a defined height difference probability triggers off a theoretical wave with the same probability of excess, was verified in four upland basins whose river mouths are located within Kraków metropolitan area. It was proved that in order to meet the assumption made, it is necessary for the precipitation duration, with defined height difference probability, to last 48 hours, because for daily precipitation the volume of calculated theoretical flood wave is too small. During the calculations, the hydrological model was used, as was the formula for flood wave volume determination for the area of Upper Vistula River, as developed by the main author of the publication. The relative error of the reduced volumes in relation to the volumes calculated with the Kraków method for theoretical flood waves, was lower than 30% in any case. Therefore, it can be acknowledged that the suggested method may be used for determining theoretical flood waves in any cross-section for the non-gauged catchment with a surface not exceeding 400 km 2 .
The runoff coefficient is one of the basic hydrological characteristics of the catchment. It can be determined using multiannual, periodic, or annual data measurement sequences. The variability of the runoff coefficient can be influenced by the terrain, the land cover, and the land-use in the catchment, among other things.The present study is an attempt to analyse changes in the runoff coefficient over a period of 30 years (1984-2013) for 49 gauging sections located in the Carpathian part of the Upper Vistula catchment. An additional analysis was carried out to study the impact of changes in the land cover and land-use of the catchment on the value of the runoff coefficient. Rainfall and daily flows data was made available by IMGW-PIB, whereas land cover and land-use data of the catchment come from the CORINE Land Cover system (1990, 2000, 2000, and 2012).
Aim of the studyThe aim of this study is to provide temporal-spatial characteristics of rainfall distribution variability in the Cracow area, based on the new method of determining spatial distribution, as well as establishing the areas of the highest and lowest rainfall variability as compared to a multi-annual period. Material and methodsFor the calculations, 10-minute precipitation data sequences were used from the period of 2013-2016 (recorded by the MPWiK's precipitation monitoring system in Cracow; from 18 precipitation stations) as well as daily and monthly precipitation data sequences from the multi-annual period 1951-2018 (recorded at the Kraków-Obserwatorium station by the IMGW).The rainfalls observed in the period of 2013-2016 were compared to the rainfalls from the multi-annual period of 1951-2018 contrasting the average monthly and annual precipitation totals, as well as the maximum daily precipitation totals in the summer months. The comparison was made by calculating the degree of exceedance or subceedance of the average values in [%] in relation to the Kraków-Obserwatorium station, which was chosen as the benchmark. The last stage of the study was to create, in the geodata and geoinformation environment , bitmaps of spatial distribution of precipitation in the Cracow area. For drawing the isolines, the interpolation method was used. Results and conclusionsThat methodology: a) uses data from multiple precipitation stations in the researched area, b) allows for the comparison of precipitation quantities for a given period versus the data from the multi-annual period (utilizing a benchmark), c) continuously monitor precipitation variability occurring in the researched area.
Parametric flow hydrographs are used for design and management purposes in such fields as water management and aquatic engineering. They describe a theoretical hydrograph based on such parameters as maximum flow, time to peak, and surge duration. They are used to forecast flood risk and to evaluate the impact of land use on the runoff hydrograph. In Western Europe for many years methods have been used in which parametric hydrographs are determined based on physical catchment descriptors (PCDs), which are divided into three groups describing the physical features of a catchment. These descriptors are used to derive formulae enabling the determination of parametric flow hydrographs for any computational cross-section. In this work, such formulae are derived for the catchment of the Raba River, using the principles of design hydrology applied in Western European countries. The parametric hydrograph is described using Baptista's gamma density function. The input hydrograph was a nonparametric flow hydrograph determined by Archer's method. For nine gauging stations located in the Raba catchment, physical catchment descriptors were obtained for two 30-year periods: 1961-1990 and 1983-2012. Based on the nonparametric flow hydrograph and the PCDs, two groups of formulae were derived to describe the parametric hydrograph. Analysis of agreement between the computed parametric flow hydrographs and the input hydrograph indicated a high quality of fit. It should be noted that the formulae and analysis presented here refer only to the Raba catchment. However, the results confirm the possibility of applying these methods to the determination of parametric flow hydrographs for any river cross-section.
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