Yes / Manning’s roughness coefficient (n) has been widely used to estimate flood discharges and flow depths in natural channels. Therefore, although extensive guidelines are available, the selection of the appropriate n value is of great importance to hydraulic engineers and hydrologists. Generally, the largest source of error in post-flood estimates is caused by the estimation of n values, particularly when there has been minimal field verification of flow resistance. This emphasizes the need to improve methods for evaluating the roughness coefficients. Trinidad and Tobago currently does not have any set method or standardised procedure that they use to determine the n value. Therefore, the objective of this study was to develop a soft computing model in the calculation of the roughness coefficient values using low flow discharge measurements for a stream. This study presents Gene-Expression Programming (GEP), as an improved approach to compute Manning’s Roughness Coefficient. The GEP model was found to be accurate, producing a coefficient of determination (R2) of 0.94 and Root Mean Square Error (RSME) of 0.0024.

<p>A big responsibility lies in the hand of local authorities to exercise measures in preventing fatalities and damages during flood occurrences. However, the problem is how flooding can be prevented if nobody knows when and where it will be occurring, and how much water is expected. Therefore, the utilisation of flood models in such studies can be helpful in simulating what is anticipated to occur.</p><p> </p><p>In this study, the HEC-RAS steady flow model was used in calibrating different flood events in Testeboån river, which is situated in the municipality of Gävle in Sweden. The purpose is to provide inundation maps that show the water surface profiles for the various flood events that can help authorities in planning within the area. Moreover, the study would try to address certain issues, which concern one-dimensional models like HEC-RAS in terms of the effects of topographic data and the parameters used for friction coefficient.</p><p> </p><p>Various flood maps were produced to visualise the extents of the floods. In Oppala and Norra Åbyggeby, the big water extents for both the 100-year and the highest probable floods were visible in the forested areas and grasslands, although a few houses were within the predicted flooded areas. In Södra Åbyggeby, Varva, Forsby, and in the northern parts of Strömsbro and Stigslund, the majority of the residential places were not inundated during the 100-year flood calibration, but became flooded during the maximum probable flood. The southern portions of Strömsbro and Stigslund had lesser flood extents and houses were situated within the boundaries of the highest flood. In Näringen, there were also some areas close to the estuary that were flooded for both events.</p><p> </p><p>With the other calibrations performed, two factors that greatly affect the flood extents in the floodplain, particularly in flatter areas were topographic data and the parameters used as friction coefficient.  The use of high resolution topographic data was important in improving the performance of the software. Nevertheless, it must be emphasised that in areas characterised by gentler slopes that bounded the channel and the floodplain, data completeness became significant whereby both ground data and bathymetric points must be present to avoid overestimation of the inundation extent. The water extents also varied with the use of the various Manning’s <em>n</em> for the overbanks, with the bigger value showing greater water extents. Else, in areas with steeper slopes and where the water was confined to the banks, the effect was minimal.</p><p> </p><p>Despite these shortcomings of one-dimensional models, HEC-RAS provided good inundation extents that were comparable to the actual extent of the 1977 flooding.</p><p> </p><p>Modelling real floods has its own difficulties due to the unpredictability of real-life flood behaviours, and more especially, there are time dependent factors that are involved.  Although calibrating a flood event will not exactly determine what is to arise as they might either under- or overestimate such flooding occurrences, still, they give a standpoint of what is more or less to anticipate, and from this,  planning measures can be undertaken.</p>

A big responsibility lies in the hand of local authorities to exercise measures in preventing fatalities and damages during flood occurrences. However, the problem is how flooding can be prevented if nobody knows when and where it will be occurring, and how much water is expected. Therefore, the utilisation of flood models in such studies can be helpful in simulating what is anticipated to occur.   In this study, the HEC-RAS steady flow model was used in calibrating different flood events in Testeboån river, which is situated in the municipality of Gävle in Sweden. The purpose is to provide inundation maps that show the water surface profiles for the various flood events that can help authorities in planning within the area. Moreover, the study would try to address certain issues, which concern one-dimensional models like HEC-RAS in terms of the effects of topographic data and the parameters used for friction coefficient.   Various flood maps were produced to visualise the extents of the floods. In Oppala and Norra Åbyggeby, the big water extents for both the 100-year and the highest probable floods were visible in the forested areas and grasslands, although a few houses were within the predicted flooded areas. In Södra Åbyggeby, Varva, Forsby, and in the northern parts of Strömsbro and Stigslund, the majority of the residential places were not inundated during the 100-year flood calibration, but became flooded during the maximum probable flood. The southern portions of Strömsbro and Stigslund had lesser flood extents and houses were situated within the boundaries of the highest flood. In Näringen, there were also some areas close to the estuary that were flooded for both events.   With the other calibrations performed, two factors that greatly affect the flood extents in the floodplain, particularly in flatter areas were topographic data and the parameters used as friction coefficient.  The use of high resolution topographic data was important in improving the performance of the software. Nevertheless, it must be emphasised that in areas characterised by gentler slopes that bounded the channel and the floodplain, data completeness became significant whereby both ground data and bathymetric points must be present to avoid overestimation of the inundation extent. The water extents also varied with the use of the various Manning’s n for the overbanks, with the bigger value showing greater water extents. Else, in areas with steeper slopes and where the water was confined to the banks, the effect was minimal.   Despite these shortcomings of one-dimensional models, HEC-RAS provided good inundation extents that were comparable to the actual extent of the 1977 flooding.   Modelling real floods has its own difficulties due to the unpredictability of real-life flood behaviours, and more especially, there are time dependent factors that are involved.  Although calibrating a flood event will not exactly determine what is to arise as they might either under- or overestimate such flooding occurrences, still, they give a standpoint of what is more or less to anticipate, and from this,  planning measures can be undertaken.

O problema da previsão da resistência ao escoamento em canais tem atraído a atenção dos engenheiros há longo tempo. Durante os últimos decênios a resistência ao escoamento em canais abertos de fundo fixo tem sido amplamente investigada, usando rugosidade artificial nas superfícies de canais experimentais. A adoção do coeficiente de rugosidade para um canal natural significa estimar a resistência de este ao escoamento. A utilização de um valor incorreto deste coeficiente pode ter grandes impactos na estimação da vazão e em conseqüência no dimensionamento dos projetos de obras hidráulicas. Apresenta-se, mediante pesquisa bibliográfica, os métodos de cálculo para avaliação do coeficiente de rugosidade ou coeficiente de resistência, dando ênfase a aqueles desenvolvidos para canais naturais com rugosidade de grande escala, sem os efeitos do transporte de sedimentos. Em modelo físico avaliam-se os efeitos da distribuição, tamanho e forma dos elementos geométricos na resistência ao escoamento. Espera-se que os resultados da pesquisa proporcionem ao engenheiro os critérios necessários para a avaliação do coeficiente de rugosidade. Os métodos diretos de medição de vazões nos rios nem sempre podem ser levados a cabo em rios de montanha , especialmente na época de cheia, devido às grandes declividades (i>1%), material de grandes dimensões no leito (pedras, seixos, matacões), submersão relativa menor do que 1, condições estas de escoamento que podem ser perigosas para os equipamentos de medição. Em tais circunstâncias é necessário o uso de métodos indiretos. A aplicação das relações de resistência ao escoamento em rios de montanha torna-se difícil pelos escassos conhecimentos na avaliação do coeficiente de resistência. Faz-se uma comparação das diferentes formulações existentes da resistência ao escoamento com dados de um rio dos Andes peruanos, determinando-se uma equação de ajuste. / The flow resistance estimation problem in channels has attracted the engineer's attention for a long time. During the last decades the flow resistance in open channels with rigid bed has been research with the use of artificial roughness in bed flumes. Adapting a natural channel roughness coefficient means the estimation of the corresponding resistance to flow. The use of an incorrect value in this coefficient might produce a big impact in the discharge estimation, as well as in the hydraulic work project. The calculation methods to estimate the roughness coefficient or resistance coefficient are showed through this bibliographic research, attaching importance to those developed for channels with large scale roughness; this without the sediment transport effects into account. The distribution, size and shape effects of the geometric elements in the flow resistance are evaluated in a physical model. It is expected that the research results provide the engineer with the required criteria to estimate the roughness coefficient. The direct methods of the discharge measurement in rivers can not always take place in mountain rivers, owing to the following reasons: high gradients (i>1%), big dimension material (cobbles and boulders), relative submergence lower than unit; flow conditions that might be dangerous for the measuring equipment. Under these circumstances it is necessary the use of indirect methods. The application of flow resistance relations in mountain rivers turns very difficult, due to the limited knowledge in resistance coefficient evaluation. In the following research has been made a comparison of the different existing flow resistance equations in mountain rivers, for a river in the Peruvian Andes by establishing a fitting curve.

O problema da previsão da resistência ao escoamento em canais tem atraído a atenção dos engenheiros há longo tempo. Durante os últimos decênios a resistência ao escoamento em canais abertos de fundo fixo tem sido amplamente investigada, usando rugosidade artificial nas superfícies de canais experimentais. A adoção do coeficiente de rugosidade para um canal natural significa estimar a resistência de este ao escoamento. A utilização de um valor incorreto deste coeficiente pode ter grandes impactos na estimação da vazão e em conseqüência no dimensionamento dos projetos de obras hidráulicas. Apresenta-se, mediante pesquisa bibliográfica, os métodos de cálculo para avaliação do coeficiente de rugosidade ou coeficiente de resistência, dando ênfase a aqueles desenvolvidos para canais naturais com rugosidade de grande escala, sem os efeitos do transporte de sedimentos. Em modelo físico avaliam-se os efeitos da distribuição, tamanho e forma dos elementos geométricos na resistência ao escoamento. Espera-se que os resultados da pesquisa proporcionem ao engenheiro os critérios necessários para a avaliação do coeficiente de rugosidade. Os métodos diretos de medição de vazões nos rios nem sempre podem ser levados a cabo em rios de montanha , especialmente na época de cheia, devido às grandes declividades (i>1%), material de grandes dimensões no leito (pedras, seixos, matacões), submersão relativa menor do que 1, condições estas de escoamento que podem ser perigosas para os equipamentos de medição. Em tais circunstâncias é necessário o uso de métodos indiretos. A aplicação das relações de resistência ao escoamento em rios de montanha torna-se difícil pelos escassos conhecimentos na avaliação do coeficiente de resistência. Faz-se uma comparação das diferentes formulações existentes da resistência ao escoamento com dados de um rio dos Andes peruanos, determinando-se uma equação de ajuste. / The flow resistance estimation problem in channels has attracted the engineer's attention for a long time. During the last decades the flow resistance in open channels with rigid bed has been research with the use of artificial roughness in bed flumes. Adapting a natural channel roughness coefficient means the estimation of the corresponding resistance to flow. The use of an incorrect value in this coefficient might produce a big impact in the discharge estimation, as well as in the hydraulic work project. The calculation methods to estimate the roughness coefficient or resistance coefficient are showed through this bibliographic research, attaching importance to those developed for channels with large scale roughness; this without the sediment transport effects into account. The distribution, size and shape effects of the geometric elements in the flow resistance are evaluated in a physical model. It is expected that the research results provide the engineer with the required criteria to estimate the roughness coefficient. The direct methods of the discharge measurement in rivers can not always take place in mountain rivers, owing to the following reasons: high gradients (i>1%), big dimension material (cobbles and boulders), relative submergence lower than unit; flow conditions that might be dangerous for the measuring equipment. Under these circumstances it is necessary the use of indirect methods. The application of flow resistance relations in mountain rivers turns very difficult, due to the limited knowledge in resistance coefficient evaluation. In the following research has been made a comparison of the different existing flow resistance equations in mountain rivers, for a river in the Peruvian Andes by establishing a fitting curve.

Yes / The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group (RNG) k-ε model was developed to simulate the flow in the reach. In order to take the circulation currents in the bends into account, the momentum equations were improved by adding an additional source term. Comparison of the numerical simulation with field measurements indicates that the improved two-dimensional depth-averaged RNG k-ε model can improve the accuracy of the numerical simulation. A rapid adaptive algorithm was constructed, which can automatically adjust Manning's roughness coefficient in different parts of the study river reach. As a result, not only can the trial computation time be significantly shortened, but the accuracy of the numerical simulation can also be greatly improved. Comparison of the simulated and measured water surface slopes for four typical cases shows that the longitudinal and transverse slopes of the water surface increase with the average velocity upstream. In addition, comparison was made between the positions of the talweg and the main streamline, which coincide for most of the study river reach. However, deviations between the positions of the talweg and the main streamline were found at the junction of two bends, at the position where the river width suddenly decreases or increases. / National Natural Science Foundation of China (Grants No. 11361002 and 91230111), the Natural Science Foundation of Ningxia, China (Grant No. NZ13086), the Project of Beifang University of Nationalities, China (Grant No. 2012XZK05), the Foreign Expert Project of Beifang University of Nationalities, China, and the Visiting Scholar Foundation of State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, China (Grant No. 2013A011).

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-02-11T06:47:59Z No. of bitstreams: 2 Dissertação - Pérola Morais Calil - 2009.pdf: 3106835 bytes, checksum: e5ae60613d54ee5455d5dab6bcb6f09e (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-02-11T06:50:21Z (GMT) No. of bitstreams: 2 Dissertação - Pérola Morais Calil - 2009.pdf: 3106835 bytes, checksum: e5ae60613d54ee5455d5dab6bcb6f09e (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-02-11T06:50:21Z (GMT). No. of bitstreams: 2 Dissertação - Pérola Morais Calil - 2009.pdf: 3106835 bytes, checksum: e5ae60613d54ee5455d5dab6bcb6f09e (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2009-08-28 / Planning and environmental management are activities that aim to control and suitable land use for maximum agricultural yield purposes, through a powerful operating system, capable of sustaining human activities with a minimum of disturbances on physical, ecological and social processes. To ensure the rational use of natural resources, soil properties need to be taken in account, as well terrain steepness and water dynamics, since they inform about cropping intensity and agronomic practices to be applied to soils, in order to avoid exhaustion of productive capacity caused by erosion. This work aimed to assess morphometric attributes related to soil distribution over the landscape and suggest the land use potential, based on the roughness coefficient in the Alto Meia Ponte River basin (Goiás, Brazil). Among the studied variables, morphometric attributes, associated to roughness coefficient, proved to be a valuable tool for the definition of land use potentialities in the diagnosis phase. They are low cost procedures, providing suitable information about water dynamics and, or, hydrologic behavior, as well the ease of gathering information. The use of roughness coefficient resulted in initial indication of the watershed for livestock and reforestation. The intersection of roughness coefficient and soil surveys data, associated with average land slopes, allowed to discriminate more areas suited to farming activities and those more vulnerable to environmental degradation. The refinement of information enabled the increase in areas liable to agricultural use, provided that conservative and preventive measures of soil degradation are taken. / O planejamento e o manejo ambiental são atividades que visam ao controle e adequação do uso das terras com a finalidade de maximizar a produtividade agrícola por meio de um sistema de exploração eficiente capaz de sustentar as atividades humanas com um mínimo de distúrbios nos processos físicos, ecológicos e sociais. Para garantir o uso racional dos recursos naturais devem-se considerar as características das propriedades do solo, a declividade do terreno e a dinâmica das águas, pois indicam a intensidade de cultivo e o manejo a ser aplicado ao solo para que não haja exaustão da capacidade produtiva em decorrência da erosão. O objetivo desse trabalho foi avaliar os atributos morfométricos em relação à distribuição dos solos na paisagem e sugerir o potencial de uso da terra com base no coeficiente de rugosidade na bacia hidrográfica do alto rio Meia Ponte, Goiás. Dentre as variáveis estudadas, os atributos morfométricos associados ao coeficiente de rugosidade, revelaram-se de grande valor na definição da potencialidade de uso da terra, na fase de prédiagnóstico. São procedimentos de baixo custo, fornecendo informações satisfatórias sobre a dinâmica hídrica e, ou, o comportamento hidrológico, bem como a facilidade na obtenção de informações. O coeficiente de rugosidade resultou na indicação inicial do uso da bacia para pecuária e reflorestamento.Com o cruzamento dos dados do coeficiente de rugosidade e de levantamentos de solos, associados às declividades médias, foi possível discriminar mais áreas aptas às diferentes atividades (agropecuárias) e aquelas mais vulneráveis à degradação ambiental. O refinamento das informações possibilitou o aumento das áreas aptas à agricultura, desde que sejam tomadas medidas conservacionistas, preventivas da degradação do solo.

Most rock masses encountered in civil and mining engineering projects contain pre-existing discontinuities. These discontinuities weaken the rock masses to an extent, which depends very much on the size of engineering structure relation to discontinuity spacing. The strength and deformability of rock mass is controlled not only by the intact portion of rock, but by the characteristic of the joints that break up the mass, particularly their pattern and their orientation with respect to the in-situ stresses. In considering the effect of joints, the discrete approach emerged as an efficient tool and advocated since 1970s (Cundall, 1971). However, the numerical approach with modelling the joints explicitly has the limitation of computational complexity for modelling large-scale problems with extremely large number of joints. As an alternative to this limitation, the equivalent continuum approach models the jointed rock masses as a continuum with the equivalent properties that represent implicitly the effects of the joints. Several numerical methods have been developed by various researchers to model jointed rock masses as equivalent continuum, using various techniques. However, the existing equivalent continuum models are complicated and need more input data from experimental or field testing in order to carry out the analysis. Present approach attempts to use statistical relations, which are simple and obtained after analyzing a large data from the literature on laboratory test results of jointed rock masses. Systematic investigations were done including laboratory experiments to develop the methodologies to determine the equivalent material properties of rock mass and their stress-strain behaviour, using a hyperbolic approach (Duncan and Chang, 1970). Present study covers the development of equivalent continuum model for rock mass right from developing statistical correlations to find out equivalent material properties based on experimental results, to the implementation of the model in FLAC3D for 3-dimensional applications and subsequently verification leading to real field application involving jointed rocks. Experimental work carried out to study the strength and deformation characteristics of jointed rock by using standard laboratory tests on cylindrical specimens of plaster of Paris by introducing artificial joints. The objective was to derive the compressive strength and elastic modulus of rock mass as a function of intact rock strength/modulus and joint factor. The obtained experimental results and developed relations were compared with the previous experimental data on jointed rocks. Further, a failure criterion as proposed by Ramamurthy (1993) has been validated from these experimental results of intact and jointed rock specimens. Empirical relationships similar to Ramamurthy’s relations are established for the prediction of rock mass strength and were compared with proposed equation by Ramamurthy (1993) and are found comparable. However, the equations by Ramamurthy were based on different variety of rocks and therefore recommended for further use and were used in numerical models. For efficient application to the field problems the equivalent continuum model is implemented in the program Fast Lagrangian analysis of continua (FLAC3D). The model was rigorously validated by simulating jointed rock specimens. Element tests were conducted for both uniaxial and triaxial cases and then compared with the respective experimental results. The numerical test program includes laboratory tested cylindrical rock specimens of different rock types, from plaster of Paris representing soft rock to granite representing very hard rock. The results of the equivalent continuum modelling were also compared with explicit modelling results where joints were incorporated in the model as interfaces. To represent highly discontinuous system, the laboratory investigation on block jointed specimens of gypsum plaster (Brown and Trollope, 1970) was modelled numerically using equivalent continuum approach. To extend the applicability of the model to field applications, investigation were done by undertaking numerical modelling of two case studies underground caverns, one Nathpa Jhakri hydroelectric power cavern in Himachal Pradesh, India, and the other one Shiobara hydroelectric power cavern in Japan. This study verifies the efficiency of the present approach in estimating ground movement and stress distribution around the excavations in jointed rock masses. The modelling results were also compared with six other computation models as presented by Horii et al. (1999) for the Shiobara power house cavern. An attempt has also been made to numerically model the support system for the cavern and investigate the efficiency of reinforcements using FLAC3D. The model was also used for analyzing large scale slope in jointed rocks using the equivalent continuum model by undertaking numerical modelling of Anji bridge abutment slopes, in Jammu and Kashmir, India. Slope stability analysis is done using equivalent continuum approach for both, the original profiles as well as with the pier loads on cut profiles. Attempt was also made to exhibit the shear strength dependency of the strain though the hyperbolic stress- strain model. The shear strain developed in the slope increases with reducing the shear strength. The relationship between the shear strength reduction ratio ‘R’ and axial strain ‘ε’, for different values of failure ratio ‘Rf’ was studied and it was observed that, the value of ‘ε’ increases, as the value of ‘R’ increases especially it increases rapidly when the value ‘R’ approaches certain critical value, which varies with the value of ‘Rf’. This critical value of R is known as the critical shear strength reduction factor Rc and is highly sensitive to the confining stress. As the value of Rf increases, representing a transition from linear elastic nature to nonlinear nature, the value of critical shear strength reduction ratio also decreases. Relationship between the critical shear strength reduction ratio and the safety factor were examined to elucidate their physical meaning. It was observed that at critical value of the shear strength reduction ratio, a well defined failure shear zone developed from the toe to the crest of the slope. Intelligent models using ANNs were also developed to predict the elastic modulus of jointed rocks as an alternative to empirical equations and without predefining a mathematical model to correlate the properties.

Hydrological models are used widely and they demand for multiple input variables and observations. One of those variables is Manning’s roughness coefficient. In the current literature the variability of the coefficient poses an unknown uncertainty. This study examines a small river channel located in central Sweden, and aims to determine the variability and uncertainty of the roughness coefficient during diverse vegetation conditions within the channel. During multiple field visits to the location, slope, water level and cross-section examination is performed. With numerical simulation, discharge and roughness coefficients are obtained. With the hydraulic model (HEC-RAS), stage-discharge rating curves are produced and extrapolation is applied to obtain high flows. Manning’s roughness coefficients and their uncertainties are assessed by two different approaches. Determining the coefficient in a simplified sensitivity analysis by using Manning’s equation and calibrating HEC-RAS while applying Mean absolute error (MAE) calculation. The calculated roughness coefficients presents higher range when using Manning’s equation (summer vegetation conditions – 0.2, winter vegetation conditions – 0.095). On the contrary MAE provides values closer to each other (summer – 0.15, winter – 0.11). The obtained results indicate a high variance between summer and winter vegetation conditions, producing 38 cm water level differences during high flows using Manning’s equation and 6 cm difference using the calibration of the model in HEC-RAS. These results confirm that the roughness coefficient cannot be assumed to be constant throughout different seasons as had been assumed widely when applying hydrological modelling. Throughout the study innovative approaches and methods (e.g. back-calculating from Manning’s equation and calibrating HEC-RAS based on observed water levels) are used in order to determine the consequences of ignoring the variability of the roughness coefficient. Due to the study, one can derive that vegetation needs to be considered in having an important impact on the varying roughness coefficient value and it cannot be left as a constant value within hydrological models. / Hydrologiska modeller är vanligt förekommande för bestämning av vattenföringsprognoser, och kräver ett flertal indata variabler och observationer. En av variablerna är Mannings råhetskoefficient, som orsakar en okänd felmarginal i den hydrologiska modellen. Den här studien syftar till att avgöra osäkerheten av felmarginalen samt variationen av Mannings råhetskoefficient. Det görs genom att undersöka en liten bäck i centrala Sverige vid olika vegetationstillstånd. Flera fältundersökningar genomfördes där tvärsnittsmätningar, vattennivå och hydraulisk gradient bestämdes. Från numerisk simulering kan flöde och råhetskoefficienten kalkyleras. Genom den hydrauliska modellen (HEC-RAS) fås ratingkurvor för vattennivå och flöde, där extrapolering görs för de högre flödena. Mannings råhetskoefficient och dess osäkerhet undersöks med två olika tillvägagångssätt. Den första metoden bygger på att använda Mannings ekvation. Den andra metoden bygger på att först genomföra en kalibrering i HEC-RAS och sedan använda kalkylering av medel-absolut-avvikelse, ”Mean absolute error” (MAE). Råhetskoefficienten beräknad med hjälp av Mannings ekvation ger större spridning (sommar – 0.2, vinter – 0.095) än vid användning av MAE beräkning (sommar – 0.15, vinter – 0.11). Resultatet visar en stor skillnad mellan så kallad vinter och sommar vegetation. Skillnaden i vattennivå är 38 cm vid användning av första metoden och 6 cm vid användning av den andra metoden. Resultaten från den här studien visar att råhetskoefficienten inte kan antas vara stabil under olika säsonger, vilket antas vid hydrologisk modellering. Innovativa metoder, så som bak-kalkylering från Mannings ekvation och kalibrering i HEC-RAS baserad på observerade vattennivåer har används för at bestämma utvärdera konsekvenserna av att ignorera variationen av råhetskoefficienten vid modellering. Den här studien visar att variationen av råhetskoefficienten påverkas av vegetationsförhållandet och att koefficienten inte kan antas konstant för korrekt modellering.

The object of this Master`s thesis is the river training of the Luha river in Jeseník nad Odrou. The thesis is divided into several chapters. In the theoretical introduction, the problems of the sediment flow regime are discussed. Moreover, it deals with the questions associated with the roughness in open channels and adjustment of riparian zones. As a part of the overall proposal of the flow adjustment, the hydraulically most suitable cross section in cunette is proposed. It is done with respect to the desired velocity ratios in the profile. Since the new cunette shape was established, the adjustment of vertical alignment was proposed. The thesis also contains the capacity assessment of the existing channel. Design of adjustment of flood protection measures includes mainly spatial rearrangement and increase the crest of levees with respect to the local conditions. The thesis also suggests the placement of vegetation in the riparian zones. Furhermore, the work deals with problems arising from the flow adjustment considering applicable laws and regulations of the Czech Republic. In the case of project implementation, it is necessary to evaluate these problems independently.