The target of diploma thesis is to design and review flood protection in Prostejov, especially for district Vrahovice. Flow capacity of river Romze will be determined too, because the river flows through the area of interest.

Depuis 25 ans, plus de 200 personnes ont perdu la vie dans le Sud de la France suite à une inondation (Vaison-la-Romaine en 1992, Aude en 1999, Gard en 2002, Var en 2010…). La sauvegarde des populations est affichée comme une priorité des pouvoirs publics, pourtant nous manquons encore d'une caractérisation globale de la vulnérabilité des personnes face aux phénomènes hydrométéorologiques. Ce travail de thèse postule que la mortalité liée aux catastrophes naturelles n’est pas fortuite. Elle reflète des vulnérabilités structurelles et conjoncturelles. L’analyse fine des circonstances de décès et du profil des victimes met en évidence les facteurs qui déterminent la mortalité face à de tels phénomènes et aide à mieux cibler la prévention. Ce travail s’appuie en grande partie sur la constitution d’une base de données géoréférencée pour la période 1988-2011 collectant les lieux, les circonstances et le profil des victimes. La zone d’étude couvre la France Méditerranéenne soumise aux crues « torrentielles » dans un triangle allant des Pyrénées-Orientales à l’Ardèche et au Var. L’analyse permet de remettre en perspective les préjugés d’une vulnérabilité « supposée » (femmes, enfants, personnes âgées…) sur lesquels porte de façon « réflexe » la prévention. Pour les inondations majeures (plus de dix décès) qui totalisent les 2/3 du bilan humain, les décès à domicile sont prépondérants. Les circonstances de décès laissent apparaitre une vulnérabilité subie liée à l’exposition des personnes (par exemple dans un bâti inadapté) ou une vulnérabilité structurelle liée à la capacité des personnes à résister à l’eau. A l’inverse, pour les petits évènements, moins meurtriers mais récurrents, se dégage une vulnérabilité plus « active » qui se traduit par des comportements à risque, conscients ou inconscients, notamment liés aux déplacements. La troisième partie de la thèse envisage les leviers de prévention aptes à réduire ces bilans humains. Une bonne connaissance des circonstances de décès et des facteurs expliquant la mortalité liée aux crues méditerranéennes permet d’évaluer l’efficacité et l’efficience des mesures de gestion du risque et laisse entrevoir des potentialités de « décès évitables » en ciblant les mesures de prévention adéquates. / For 25 years, more than 200 people have died in Southern France due to flooding (Vaison -la-Romaine in 1992, Aude in 1999, Gard in 2002, Var in 2010 ...). Preserving populations appears to be a government priority, however we still lack a comprehensive characterization of the vulnerability of people face to hydrometeorological phenomena. This thesis assumes that the mortality from natural disasters is not accidental. It reflects structural and circumstantial vulnerabilities. The detailed analysis of the circumstances of death and profiles of victims highlights the factors that determine mortality in this phenomena and help to improve disaster prepearedness. This work is based largely on the building of a georeferenced database for the period 1988-2011 addressing the places, the circumstances of death and the profile of the victims. The study area covers the Mediterranean France departments prone to flash floods from the Pyrenees-Orientales to the Ardeche and Var. The analysis relativizes a "supposed" vulnerability (women, childrens, elderly...). For major flooding (more than ten deaths) totaling 2/3 of losses of life, the deaths at home are most numerous. The circumstances of death let appear a sustained vulnerability to human exposure (eg. unsuitable buildings) or structural vulnerability to people's ability to resist water. In contrast, for small events, less deadly but mor recurring exudes a vulnerability more "active" which translates risk behaviors, conscious or unconscious, particularly related to displacements. The third part of the thesis considers the levers prevention able to reduce loss of life. A good knowledge of the circumstances of death and factors explaining mortality from Mediterranean floods used to assess the efficiency and effectiveness of risk management measures and suggests the potential of "avoidable deaths" targeting prevention adequate.

Key theoretical and empirical results from the past two decades have established that peak discharges exhibit power-law, or scaling, relation with drainage area across multiple scales of time and space. This relationship takes the form Q(A)= $#945;AΘ where Q is peak discharge, A is the drainage area, Θ is the flood scaling exponent, and α is the intercept. Motivated by seminal empirical studies that show that the flood scaling parameters α and Θ change from one rainfall-runoff event to another, this dissertation explores how certain rainfall and catchment physical properties control the flood scaling exponent and intercept at the rainfall-runoff event scale using a combination of extensive numerical simulation experiments and analysis of observational data from the Iowa River basin, Iowa. Results show that Θ generally decreases with increasing values of rainfall intensity, runoff coefficient, and hillslope overland flow velocity, whereas its value generally increases with increasing rainfall duration. Moreover, while the flood scaling intercept is primarily controlled by the excess rainfall intensity, it increases with increasing runoff coefficient and hillslope overland flow velocity. Results also show that the temporal intermittency structure of rainfall has a significant effect on the scaling structure of peak discharges. These results highlight the fact that the flood scaling parameters are able to be estimated from the aforementioned catchment rainfall and physical variables, which can be measured either directly or indirectly using in situ or remote sensing techniques. The dissertation also proposes and demonstrates a new flood forecasting framework that is based on the scaling theory of floods. The results of the study mark a step forward to provide a physically meaningful framework for regionalization of flood frequencies and hence to solve the long standing hydrologic problem of flood prediction in ungauged basins.

Flash floods caused by localized thunderstorms are a natural hazard of the semi -arid Southwest, and many communities have responded by installing ALERT flood forecasting systems. This study explored a rainfall- runoff modeling approach thought to be appropriate for forecasting in such watersheds. The kinematic model KINEROS was evaluated because it is a distributed model developed specifically for desert regions, and can be applied to basins without historic data. This study examined the accuracy of KINEROS under data constraints that are typical of semi -arid ALERT watersheds. The model was validated at the 150 km2, semi -arid Walnut Gulch experimental watershed. Under the conditions examined, KINEROS provided poor simulations of runoff volume and peak flow, but good simulations of time to peak. For peak flows, the standard error of estimate was nearly 100% of the observed mean. Surprisingly, when model parameters were based only on measurable watershed properties, simulated peak flows were as accurate as when parameters were calibrated on some historic data. The accuracy of KINEROS was compared to that of the SCS model. When calibrated, a distributed SCS model with a simple channel loss component was as accurate as KINEROS. Reasons for poor simulations were investigated by examining a) rainfall sampling errors, b) model sensitivity and dynamics, and c) trends in simulation accuracy. The cause of poor simulations was divided between rainfall sampling errors and other problems. It was found that when raingage densities are on the order of 1/20 km2, rainfall sampling errors preclude the consistent and reliable simulation of runoff from localized thunderstorms. Even when rainfall errors were minimized, accuracy of simulations were still poor. Good results, however, have been obtained with KINEROS on small watersheds; the problem is not KINEROS itself but its application at larger scales. The study also examined the hydrology of thunderstorm -generated floods at Walnut Gulch. The space -time dynamics of rainfall and runoff were characterized and found to be of fundamental importance. Hillslope infiltration was found to exert a dominant control on runoff, although flow hydraulics, channel losses, and initial soil moisture are also important. Watershed response was found to be nonlinear.

This thesis defines a methodology for the evaluation of the worth of streamflow data using a Bayes risk approach. Using regional streamflow data in a regression analysis, the Bayes risk can be computed by considering the probability of the error in using the regionalized estimates of bridge or culvert design parameters. Cost curves for over- and underestimation of the design parameter can be generated based on the error of the estimate. The Bayes risk can then be computed by integrating the probability of estimation error over the cost curves. The methodology may then be used to analyze the regional data collection effort by considering the worth of data for a record site relative to the other sites contributing to the regression equations. The methodology is illustrated by using a set of actual streamflow data from Missouri. The cost curves for over- and underestimation of the streamflow design parameter for bridges and culverts are hypothesized so that the Bayes risk might be computed and the results of the analysis discussed. The results are discussed by demonstrating small sample bias that is introduced into the estimate of the design parameter for the construction of bridges and culverts. The conclusions are that the small sample bias in the estimation of large floods can be substantial and that the Bayes risk methodology can evaluate the relative worth of data when the data are used in regionalization.

No description available.

No description available.

In order to study the influence on blue-green algal nitrogenase activity of environmental variables in deepwater rice-fields (DWR), a laboratory study was planned on a DWR isolate of Calothrix (D764). The variables chosen were light, oxygen, combined nitrogen, phosphorus and iron. As availability of P is likely to play an especially important role for growth and nitrogen fixation in DWR, studies on phosphatase activity of the isolate were also included. The method used for measuring nitrogenase activity was acetylene reduction assay (ARA). In order to convert nitrogenase activity to nitrogen fixation, the conversion ratio of N(_2) : C(_2)H(_2) reduced was determined by comparing the total amount of N fixed with total C(_2)H(_2) reduced. The ratio was 1 : 4.1 and 1 : 5.2 at 85 and 10 µmol photon m(^-2) s(^-1), respectively. Changes in nitrogenase activity in batch culture were studied in relation to growth characteristics. Maximum activity (10.5 nmol C(_2)H(_4) mg d. wt(^-1) min(^-1)) was observed after two days of growth. During this period, juvenile trichomes (hence maximum heterocyst frequency) were abundant and cyanophycin granules were absent; chl a, phycobiliprotein and algal N decreased. It is suggested that the juvenile filament is the most active nitrogen-fixer during the growth of the alga. The response of nitrogenase to changes in light flux (down- or upshift) was rapid. The alga showed a marked drop in nitrogenase activity in the dark, but subsequent changes were slow, with detectable activity after 24 h. Higher nitrogenase activity was observed when the dark grown alga was re-illuminated, than the maximum activity found under continuous illumination. Nitrogen fixation and heterocyst differentiation were suppressed when 10 mg 1(^-1) NH(_4)-N was added to a batch culture. Fe-deficient cultures had lower nitrogenase activity and N content than Fe-sufficient cultures. Fe- deficiency led to the development of a series of new heterocysts apical to the basal ones. Addition of Fe to Fe-deficient cultures led to a marked increase in nitrogenase activity and loss of the degenerated basal heterocysts. The alga was capable of using a number of organic P substrates as the sole source of phosphorus and showed both cell-bound phosphomono- and phosphodiesterase activities. In batch culture, phosphatase activity was detected when cellular P content dropped to 0.98%. A brief study on the influence of the environmental factors on cell-bound phosphatase activities of the alga has been included. A brief comparison in nitrogenase activity of a UK field Rivularia population and bacterised laboratory isolate Rivularia D403 was made and probable behaviour of algae in DWR is discussed.

With urbanisation continuing to encroach upon flood plains, the constant replacement of permeable land with impermeable surfaces and with the changes in global climate, the need for improved flood modelling is ever more apparent. A wide range of methods exist that simulate surface flow; most commonly in one-dimensional (1D) or twodimensional (2D), and more recently on smaller scales in three-dimensional (3D) models. In urban flood modelling, 2D models are often the preferred choice as they can simulate surface flow more accurately than their 1D model counterparts; they are, however, more computationally demanding and thereby usually require greater simulation time. With the vast amount of information used in flood modelling, generalisation techniques are often employed to reduce the computational load within a simulation. The objective of this thesis is to improve 2D flood modelling in urban environments by introducing a new and novel approach of representing fine scale building features within coarse grids. This is achieved by creating an automated approach that data-mines key features such as buildings and represents their effects numerically within a multiple layer grid format. This new approach is tested in comparison to two other, already established generalising techniques which are single layer based. The effectiveness of each model is assessed by its ability to accurately represent surface flow at different grid resolutions and how each copes with varying building orientations and distributions within the test datasets. The performance of each generalising approach is determined therefore by its accuracy in relation to the fine scale model and the difference in the computational time required complete the simulation. Finally the multilayered methodology is applied to a real case scenario to test its applicability further. Overall it revealed, as predicted, that the multilayered approach enables far greater accuracies at routing surface flow within coarse grids whilst still greatly reducing computational time. As a further benefit in urban flood modelling, this thesis shows that using a multilayered data format it is possible to simulate the influence of features that have a grid resolution finer than the initial terrain topology data, thus enabling, for example, the routing of surface water through alleyways between buildings that have a width less than one meter.

The research presented in this Thesis aims at defining the strengths and weaknesses of an Improved 1D/1D model when compared with a more accurate 1D/2D model. Although both coupled-models (sewer/surface) solve the St.\ Venant equations in both layers, the latter uses a higher approximation (2D two-dimensional) on the surface layer. Consequently, the 1D/1D model is computationally more efficient when compared to the 1D/2D model, however there is some compromise with the overall accuracy. The hypothesis is that "The inundation extent of urban flooding can be reproduced by 1D/1D models in good agreement with the 1D/2D models if the results are kept within certain limits of resolution and under certain conditions". The Thesis starts by investigating ways of improving an existing 1D/1D model to rival the more accurate 1D/2D model. Parts of the 1D/1D model code are changed and new algorithms and routines implemented. An innovative GIS tool translates the 1D output-results into 2D flood-inundation-maps enabling a thorough comparison between the two models. The methodology assures the set-up of two equivalent models, which includes a novel algorithm for calibrating the 1D/1D model vs.\ the 1D/2D model results. Developments are tested in two distinctly different case studies of areas prone to flooding. The conclusion is that the 1D/1D model is able to simulate flooding in good agreement with the 1D/2D model; however, it is found that features such as topography, density of the urbanised areas and rainfall distribution may affect the agreement between both models. The work presented herein is a step forward in understanding the modelling capabilities of the analysed coupled-models, and to some extent may be extrapolated to other models. Research is growing in urban flooding and this work may well prove to be a strong foundation basis for future research.