Flood hazard mapping remains challenging in regions with limited hydrological and topographic data, despite increasing flood risk driven by climate change and land-use dynamics. This study aims to demonstrate that preliminary flood inundation maps can be developed under data-scarce conditions by integrating limited field observations with publicly available datasets and simplified hydrodynamic modeling. The Khlong Wat watershed in southern Thailand, where flood hazard maps had not previously existed despite recurrent flood events, was used as a case study. Flood simulations were conducted using the HEC-RAS model with a simplified terrain representation to approximate river bathymetry, acknowledging uncertainties in channel geometry. Hydrodynamic results show a systematic increase in flood extent and depth with increasing flood recurrence intervals, with inundated areas expanding from 1.43 km2 for a 10-year flood to 4.02 km2 and 5.97 km2 for 100- and 500-year events, respectively. Agricultural land is consistently the most affected category, accounting for more than two-thirds of the flooded area across all scenarios, with rubber plantations being the dominant land use. Urban exposure increases with flood magnitude, although most buildings remain affected by shallow inundation below 0.5 m. The results confirm that meaningful flood hazard assessments can be achieved in data-limited regions and provide a transferable framework to support flood risk management and spatial planning in similar environments.

The role of hydraulic parameters in sediment transport and heavy metals concentration still needs scientific research. In this study, GIS techniques, IBER (a 2D hydrodynamic modeling system) and statistical analysis were applied to assess heavy metals concentration, spatial distribution and sources. A total number of 30 surface sediment samples were collected from the Stare Miasto two-stage reservoir. Results showed that median values follow order Zn > Pb > Cu > Cr > Ni > Cd, which was characteristic for both parts of the reservoir. The overall calculated median concentrations of Zn, Pb, Cu, Cr, Ni, and Cd were 6.74, 1.66, 1.14, 0.99, 0.8, and 0.04 mg/kg. Analysis of heavy metals concentration shows that higher mean values were observed in the pre-dam part for all of the analyzed heavy metals. The highest risk was observed for Zn, Pb and Cd for all of the analyzed samples. Statistical analysis showed that heavy metals concentration is correlated with the fraction of sediments and distance from the inflow. Spearman’s rank correlation showed that hydraulic parameters affect heavy metals concentration. Critical diameter was negatively correlated with Cu while Froude number and velocity were negatively correlated with Cu and Zn concentrations. Also, it was observed that Cu concentrations in the main zone were positively correlated with specific discharge. Results showed that the two-stage construction of the reservoir has an impact on the limitation of sediments spatial distribution and helps to control pollution related to heavy metals.

The Warta River basin, Poland’s third-largest basin, is highly vulnerable to drought, which occurs in both cold and warm seasons. This study examined meteorological and hydrological droughts using daily temperature and precipitation data from 211 meteorological stations and discharge data from 15 hydrological gauges for 2000–2020. Four indicators were applied: SPI and SPEI for meteorological drought, and SRI and ThLM for hydrological drought. The analysis revealed prolonged droughts and a systematic decline in SRI values, especially from March to September. The longest event, a shallow drought, lasted 555 days between 2019 and 2020 at the Sławsk gauge. The period from 2018 to 2020 was particularly severe, with drought intensity increasing and affecting 70–80% of river flows, while events persisted longer than usual. Water withdrawals, especially for municipal use, further reduced river levels. The section between Uniejów and Oborniki, located downstream of one of Poland’s largest reservoirs, proved most vulnerable to hydrological drought. Overall, results indicate a deteriorating water situation in the Warta basin, with the most significant deficits in spring and summer. These trends pose serious challenges for water management and water supply security. An improved understanding of meteorological and hydrological droughts and their impact is essential for managing the water–food–environment–energy nexus, including restrictions on water use for domestic, economic, and agricultural purposes, as well as the functioning of aquatic ecosystems.

There have been many destructive pluvial and fluvial floods in Poland and the projection of increasing flood hazards in the future is a reason of considerable concern. The maps of river hazard zones are changing over time, and understanding these changes is of primary importance for flood risk reduction and climate change adaptation. This article aims to assess the impact of climate change on the spatial extent and depth classes of flood hazard zones for a selected reach of the River Warta in the western part of Poland. To this end, we integrated the Soil Water Assessment Tool (SWAT) hydrological model of the Warta River Basin with the 1D hydraulic model HEC-RAS of the selected reach. The climate change effect was quantified based on the coupled model simulations forced with bias-corrected projections from the EURO-CORDEX project. Flood hazard maps were developed for two townships along the River Warta (Oborniki and Wronki), three greenhouse gas concentration scenarios (one for the baseline scenario in the reference period, 1971–2000; one for RCP 4.5 and one for RCP 8.5, for the time horizon 2021–2050) and for three return periods (10-, 100- and 500-year floods). Based on the ensemble mean, the increase in the flooded area projected in the future is more pronounced for RCP8.5 than for RCP4.5. This unique combination of software and data enabled the transformation of climate change impact into the land surface part of the hydrological cycle and assessment of changes in flood hazard and opens the way to assess the potential increases in the economic losses in the future.

Study region: The research object is located in Wielkopolska province (Poland), which is well-known for its rural character and scarcity of water. To prevent droughts, small reservoirs are installed in local watersheds. It enables control of water conditions for agriculture and improvement of local climate. The main challenge is prevention from the deposition of sediments in a reservoir. To minimize this threat, the specific constructions of the reservoir are applied, e.g. internal dams. Study focus: The Stare Miasto reservoir consists of an internal dam with the upper zone separated. The highway bridge split the main part. In 2014 a flood wave propagated through the reservoir. The crest of the internal dam was shifted generating a potential risk of internal dam failure. The consequences of such an event were analyzed using a two-dimensional hydrodynamic numerical tool that solves the shallow water equations with finite volume method on unstructured mesh. New hydrological insight for the region: The results obtained prove that the dam break increases the risk of bridge instability. The shear stresses generated during break of internal dam may exceed 50 N/m2, what cause danger of deep scour generation under and below the construction. Unexpectedly, the existence of the bridge decreased the threat of the main dam overtopping. The study may be a valuable inspiration for the design of new reservoirs inevitable in controlling water resource conditions in the region.

Mine tailings are commonly stored in off-stream reservoirs and are usually composed of water with high concentrations of fine particles (microns). The rupture of a mine-tailings pond promotes, depending on the characteristics of the stored material, the fluidization and release of hyper-concentrated flows that typically behave as non–Newtonian fluids. The simulation of non–Newtonian fluid dynamics using numerical modelling tools is based on the solution of mass and momentum conservation equations, particularizing the shear stress terms by means of a rheological model that accounts for the properties of the fluid. This document presents the extension of Iber, a two-dimensional hydrodynamic numerical tool, for the simulation of non–Newtonian shallow flows, especially those related to mine tailings. The performance of the numerical tool was tested throughout benchmarks and real study cases. The results agreed with the analytical and theoretical solutions in the benchmark tests; additionally, the numerical tool also revealed itself to be adequate for simulating the dynamic and static phases under real conditions. The outputs of this numerical tool provide valuable information, allowing researchers to assess flood hazard and risk in mine-tailings spill propagation scenarios.

In Europe, the routes of most watercourses were straightened and shortened, leading to the destruction and degradation of many natural environments. Currently, in places where it is possible, as part of the implementation of the Water Framework Directive, efforts are made to improve environmental sustainability, including improving the ecological condition of rivers. This paper presents the impact of three in-stream deflectors on changes in the section of a small lowland river—the Flinta (Poland)—where (from 2018 to 2023) detailed, systematic geodetic, and hydrometric research and an assessment of the ecological conditions were carried out. The presented results show the influence of deflectors on the initiation of fluvial processes in the transverse and longitudinal layouts of the channel. The river channel was narrowed from 6 to 5 m, and the current line shifted by almost 3 m. Changes were observed in the distribution of velocities and shear stresses, varying along the surveyed section of the river. In the first year after their application, an increase in velocity at the deflectors can be observed (from 0.2 m∙s−1 to 0.6 m∙s−1 in the deflector cross-section). In the following years, on the other hand, a clear decrease in velocity was observed in the sections between the deflectors (to 0.3 m∙s−1). The introduction of deflectors resulted in a significant increase in the values of shear stresses (from an average value of 0.0241 N∙m−2 in 2018 to 0.2761 N∙m−2 in 2023) and local roughness coefficients (from 0.045 s∙m−1/3 before the introduction of the deflectors to 0.070 s∙m−1/3 in 2023). Based on analyses of sediment samples, erosion and accumulation of bottom material were initially observed, followed by a subsequent stabilisation of particle size. Differences in grain size were observed, especially in the cross-section of the deflectors (increase in granularity d50% downstream of the deflector from 0.31 mm to 3.9 mm already 2 years after the introduction of deflectors). This study confirmed the positive impact of using deflectors on hydromorphological processes as deflectors facilitate the achievement of a good ecological status, as required by the WFD. The innovation of this paper lies in demonstrating the possibility of using small, simple structures to initiate and intensify fluvial processes, which may contribute to improving the ecological conditions of watercourses.

The aim of the study was to determine an effective variant of operation of the Golina polder to reduce flood hazard in the Warta River valley. We implemented a trial-and-error method for the development of computational variants. Our approach was based on staged analyses of alternatives, which took into account different locations and parameters of the inlet and outlet-controlling structures. Various control scenarios for flooding and draining the polder were also considered. A hybrid hydrodynamic model consisting of a 1D part for the main river area and a 2D part for the polder area was used for calculations. The model was built based on a digital elevation model (1 m resolution) and channel sections of the Warta River. The calibration was based on data collected during the flood in 2010 from the water gauge Slawsk (located directly at the Warta River) and water surface elevation measurements carried out in the polder area. Alternatives in subsequent stages were determined based on the results of previous stages, as well as experiences from the 2010 flood and consultations with the Regional Water Management Board in Poznan. The performance of the alternatives was evaluated according to six criteria that described the effectiveness of the polder operation in terms of its practical use and effectiveness in reducing flood hazard. The results showed that our approach made it possible to identify an effective variant of polder operation. Additional calculations were also performed to determine the magnitude of flows for which flooding of the polder should be considered to reduce downstream flooding.

The main problem presented in this paper is the safety inlet navigation of the waterway below the bridge in the city of Kaunas in Lithuania. The analyzed reach is located in the Nemunas river downstream of the Kaunas dam. It is a part of the waterway E–41 leading to the Klaipeda harbor on the southern coast of the Baltic Sea. The work was initiated by the Lithuanian company UAB “Inžinerinis projektavimas” with funds from the project called European Union Trans-European Transport Network (EU TEN-T). The main requirement imposed along this reach is to keep sufficient depth even in the range of the lowest flows. The depth is sufficient if it is not lower than 1.15 m for minimum flows such as Q95% and Q95% with ice. The hydraulic conditions for maximum flow Q50%, Q5%, and Q1% are also taken into account for control because the threat of hydraulic jump generation was also noticed. The research is based on georeferenced data from public and non-public sources. The hydrologic data were received from the Lithuanian Hydrometeorological Service. The physical model was created in the Water Laboratory of the Department of Hydraulic and Sanitary Engineering at Poznan University of Life Sciences, Poland. The preprocessing of spatial data in ArcGIS 10.8.2 and rules of hydraulic similarity were implemented in the process of physical model preparation. Three experiments were conducted in the laboratory with scaled values of Q95%, Q5%, and Q1%. The measurements of the water surface and evaluations of the average velocity were used to validate the 2D numerical model prepared in HEC-RAS 6.3.1. The basic layers of the HEC-RAS model were preprocessed in ArcGIS 10.8.2 by ESRI company. The numerical model was implemented to test different values of unknown roughness of the channel bottom. The simulations were conducted for the real values of Q95% and Q95% with ice and Q50%. The results of the simulations were depth and Froude number maps. These maps were classified into zones of no risk, middle risk, and high risk. ArcGIS in the post-processing phase was applied to identify the locations of the hazards. The magnitude of risk was expressed in terms of minimum depth achieved, maximum Froude number, as well as the length of the reaches with high risk related to these two factors. The threat of hydraulic jump formation below the bridge was also noticed. Conducted results confirmed that the combination of hydrodynamic simulations and geoprocessing in the pre- and post-processing stages could be a powerful tool in hydraulic engineering analyses. Additionally, it is worth noting that numerical modeling enables a wider analysis of potential conditions than could be possible with a physical model only.

The primary aim of this work is to assess the accuracy of the methods for spatial interpolation applied for the reconstruction of the spatial distribution of the Standardized Precipitation Index (SPI). The one-month version called SPI-1 is chosen for this purpose due to the known greatest variability of this index in comparison with its other versions. The analysis has been made for the territory of the entire country of Poland. At the same time the uncertainty related to the application of such computational procedures is determined based on qualitative and quantitative measures. The public data of two kinds are applied: (1) measurements of precipitation and (2) the locations of the meteorological stations in Poland. The analysis has been made for the period 1990–2020. However, all available observations since 1950 have been implemented. The number of available meteorological stations has decreased over the analyzed period. In January 1990 there were over one thousand stations making observations. In the end of the period of the study, the number of stations was below six hundred. Obviously, the temporal scarcity of data had an impact on the obtained results. The main tools applied were ArcGIS supported with Python scripting, including generally used modules and procedures dedicated to geoprocessing. Such an approach appeared crucial for the effective processing of the large number of data available. It also guaranteed the accuracy of the produced results and brought about drought maps based on SPI-1. The methods tested included: Inverse Distance Weighted, Natural Neighbor, Linear, Kriging, and Spline. The presented results prove that all the procedures are inaccurate and uncertain, but some of them provide satisfactory results. The worst method seems to be the interpolation based on Spline functions. The practical aspects related to the implementation of the methods led to removal of the Linear and Kriging interpolations from further use. Hence, Inverse Distance Weighted, as well as Natural Neighbor, seem to be well suited for this problem.

The paper includes data derived from airborne laser scanning (LiDAR) to develop a 2-D hydrodynamic model of water flow in the middle reach of the Warta River between Nowe Miasto nad Wartą and Solec. Particular attention was paid to problems associated with the conversion of a digital terrain model (DTM) for the purpose of hydraulic modelling. LIDAR data were also used in the development process of a numerical roughness model by means of the so-called vegetation stratification. The results of model calculations in the form of maximum water surface elevations of the river were compared with water surface elevations derived from levelling carried out in the field. On this basis the verification of the model results was performed. The possibilities of using data from airborne laser scanning to develop a model and assess roughness coefficients of the floodplains were also examined.

Abstract A methodology for quantification of the impact of sediment transport on flood hazard is proposed. The applied algorithm consists of several Python scripts for automation of sediment routing, hydrodynamic simulations, and geoprocessing of results. Flood hazard maps are uniquely linked with particular simulations of morphological changes in a river. Finally, the maps are stochastically processed. The proposed procedure was applied for a selected reach of the Warta river, located in Poland. Simulations were run for 6‐ and 12‐year flow series composed randomly on the basis of historical data. The 30 flow series for each period and four functions describing the transport of sediment were treated as uncertain variables. It was assumed that the features characterising the mean sample may properly represent the sediment content in the river reach studied. The final results are presented as maps showing the probabilities of inundation. The comparison of results with literature data confirmed the significance of the impact related to sediment transport processes on the quantification of flood hazard uncertainty. The main advantages of the presented algorithm are effective management of simulations and processing of results obtained in 240 runs of the sediment routing model.

The possibility of effective control of selected dams in the Noteć Bystra river is analyzed. Such a control is expected to permit inundation of selected arable areas, e.g., peat grasslands, to avoid flooding of the city of Czarnków and the terrains located downstream. The chosen case study is the reach of the Noteć River between the dams Pianowka–Mikolajewo–Rosko. The analysis was made on the basis of simulations of the flow and regulation of dams in flood conditions. The flow peaks of hypothetical flood waves were designed according to the directions of the ISOK project (Informatyczny System Osłony Kraju przed nadzwyczajnymi zagrożeniami—IT System of the Country’s Protection Against Extreme Hazards) as the maximum flows over 10-years (p = 10%), 100-years (p = 1%), and 500-years (p = 0.2%). The obtained results are presented as longitudinal profiles of the water surface, maps of inundated areas and maps of inundated soils. The main conclusion is that the robust control of dams reduces the peak of flow during flood wave propagation and forces inundation of the a priori selected areas. It helps to decrease the spatial range of the flood hazard and significantly reduces risk related to floods.

The paper presents the methodology and results of research conducted on the physical model in the stretch of the Neman [Polish: Niemen] River at Kaunas. The study comprised an assessment of hydraulic conditions in the river bed in the bridge profile at 214+200 km. Additionally analyses were conducted for two river bed reconstruction variants. The aim of the planned reconstruction is to adapt the Neman river bed to the parameters required for the E41 International Waterway. These studies were commissioned by a Lithuanian design office in view of the planned reconstruction and modernisation of the river fragment in accordance with the provisions of the AGN agreement concerning the network of international waterways. The river stretch in Kaunas is of key importance, as it holds a large river port, while bridge profiles are the bottlenecks due to the insufficient minimum waterway depth for safe navigation. The experimental part of the study consisted in the construction of a physical model for a 1100m river stretch including two bridge profiles (a road bridge and a railway bridge) at 214+200 km (fig. 1). The model in the 1:50/200 scale was constructed at the water laboratory of the Department of Hydraulic and Sanitary Engineering, the Poznan University of Life Sciences. The initial step was to construct a box, in which the model was made. Model geometry was recreated using the profiles/cross-sections made based on a numerical model of the area. The distance between the profiles was 50 cm. The model was supplemented with bridge piers and the existing river regulation structures (groynes and longitudinal training dams). The total dimensions of the model were 10 x 3.5 m, of which the modelled river stretch accounted for 5.5 m. Fig. 1. Physical model with the bridges and elements of the river regulation Measurements were taken for 3 variants including the current status and two reconstruction variants (dredging and development of regulation structures). Each variant was scanned in the 3D technology. The aim was to facilitate further verification of model representation accuracy with results obtained from numerical models. Hydraulic analyses were performed for four selected discharge values Q95%=1.01 dm3/s, Q50%=15.03 dm3/s, Q5%=30.31 dm3/s and Q1%=43.54 dm3/s, corresponding to actual discharges of Q95%=71.6 m3/s, Q50%=1212 m3/s, Q5%=2143 m3/s and Q1%=3079 m3/s, respectively. In order to determine conditions in the river bed for each variant in selected constant measurement profiles the distributions of water flow velocity was measured using an ADV probe. Water table gradients were measured using hydrometric gauge pins, while discharge was recorded with the use of an electromagnetic flow meter. The results were analysed with the application of e.g. the Surfer software, which was used to determine velocity distribution in the profiles above and below the bridge piers. These distributions show a considerable effect of bridge piers on velocity values and the concentration of discharges between the bridge piers (fig. 2). A similar effect on river conditions was found for the hydraulic structures strongly concentrating and directing the current within the established waterway(fig. 3). In order to provide spatial visualisation of velocity distributions tests were also conducted using a pigment. The recorded image of the pigment distribution constituted additional material facilitating qualitative evaluation of the tested variants. Fig. 2. Spatial distribution of velocities Fig. 3. Magnitudes of the flow velocities in bridge cross section The aim of the measurements was to investigate distributions of velocity and filling for all the analysed reconstruction and discharge variants. On this basis the accuracy of planned investments was verified and a slightly different location and parameters of the river regulation structures were proposed. These included two elements, i.e. the construction of groynes and training dams, and dredging of the river bed in locations identified as the shallowest. Analyses confirmed the applicability of physical modelling techniques for complex hydraulic systems and their results, next to the results of hydrodynamic modelling, may constitute a source of data for the verification of adopted design assumptions.

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 44years. Hence, the series of the lengths 40, 30 and 20years are tested and compared with reference calculations for 44years. The hydrodynamic model HEC-RAS is used to calculate water surface profilesin 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.

In the paper usefulness of one dimensional model for restoration purposes was investigated. The sediment model of downstream part of the Flinta River (Western Poland) was prepared using HEC-RAS 5.0.0. The set of deflectors, which was implemented as constrained cross-sections, was analyzed. Computations were carried out for three formulas for intensity of sediment transport: Yang, Ackers-White and MPM-Toffaleti. Two geometry variants were tested: without modifications of the channel and with deflectors. Moreover, within geometry with structures, two variants of markers for mobile beds were distinguished, where at the location of structures erosion was allowed (variant A) or blocked (variant B). The obtained results showed different responses of each formula in relation to inflow hydrographs, and impact of deflectors on sediment transport processes. At the bank opposite to structures obtained erosion while, in the location of structures, there was erosion (variant A) or deposition (variant B) of sediment. Additionally, analysis of maximum values of shear stresses indicated high peak values for variant B. Basically, results were consistent with other studies with deflectors however, the size and length of the scour, which are crucial during designing these structures, were not obtained. For this reason, one dimensional model was considered as insufficient to planning restoration measures, as simplistic information about impact of structures was not enough. The main practical output of our research is showing the limits in application ID models to analyze simple river management hydraulic structures.

The presented research analyses the impact of deflectors on sediment transport processes. The basis for analysis is a hydrodynamic model of downstream part of the Flinta river. The geometry reproduction was performed using spatial data: digital elevation model (DEM) and cross-sections of considered reach. The computations were calculated in HEC-RAS 5.0.1, a common software used to calculate water surface profiles and sediment transport. In the research, two calculation variants were analysed: (1) with initial geometry of channel, and (2) with geometry after introducing deflectors. In order to take into account uncertainty, five scenarios of 10-year flow hydrographs were tested. To calculate the intensity of sediment transport, the Engelund-Hansen formula was used. The results suggest a possible initiation of local scours near the structures.

The purpose of the paper was to present selected techniques for the control of river flow and sediment transport computations with the programming language Python. The base software for modeling of river processes was the well-known and widely used HEC-RAS. The concepts were tested on two models created for a single reach of the Warta river located in the central part of Poland. The ideas described were illustrated with three examples. The first was a basic simulation of a steady flow run from the Python script. The second example presented automatic calibration of model roughness coefficients with Nelder-Mead simplex from the SciPy module. In the third example, the sediment transport was controlled by Python script. Sediment samples were accessed and changed in the sediment data file stored in XML format. The results of the sediment simulation were read from HDF5 files. The presented techniques showed good effectiveness of this approach. The paper compared the developed techniques with other, earlier approaches to control of HEC-RAS computations. Possible further developments were also discussed.

The main purpose of the present research is to develop software for reconstruction of the river bed on the basis of sparse cross-section measurements. The tools prepared should support the process of hydrodynamic model preparation for simulation of river flow. Considering the formats of available data and the requirements of modern modeling techniques, the prepared software is fully integrated with the GIS environment. The scripting language Python 2.7 implemented in ArcGIS 10.5.1 was chosen for this purpose. Two study cases were selected to validate and test the prepared procedures. These are stream reaches in Poland. The first is located on the Warta river, and the second on the Ner river. The data necessary for the whole procedure are: a digital elevation model, measurements of the cross-sections in the form of points, and two polyline layers representing an arbitrary river centerline and river banks. In the presented research the concept of a channel-oriented coordinate system is applied. The elevations are linearly interpolated along the longitudinal and transversal directions. The interpolation along the channel is implemented in three computational schemes linking different tools available in ArcGIS and ArcToolbox. A simplified comparison of memory usage and computational time is presented. The scheme linking longitudinal and spatial interpolation algorithms seems to be the most advantageous.

This chapter is a short presentation of main theoretical concepts, which are the basis of popular flow solvers. The term "flow solver" means computer implementation of mathematical models describing river and floodplain flow. The ideas presented here are applied in commercial software, for example, MIKE11, Sobek, CCHE-1D, as well as in non-commercial packages, e.g., HEC-RAS, BASEMENT, SRH-1D, etc. The popularity of such methodologies has been growing mainly for two reasons: (1) development of fast and broadly available computers, and (2) great opportunities for application of mathematical modelling in water engineering and management problems. One example is the successful use of mathematical models in implementation of the EU Flood Directive (EP 2003, 2007; KZGW 2009).