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A flood inundation study is presented for a watershed located in south central Virginia. A HEC-RAS hydrodynamic model of the main river network was developed to assess the impact of a number of hydrologic events, including the Probable Maximum Flood (PMF), in the area of interest. The primary goal of the study was to transform discharge hydrographs produced by HEC-HMS, an event-based hydrologic model, into water surface elevations and flood inundation spatial extents. Initially, a river terrain model was constructed using data from publicly available sources and filed survey campaigns. HEC-GeoRAS and ArcGIS were used to document and integrate the considerable amount of data required for building the model. Then, a calibration process was performed using stage-discharge predictor curves. The HEC-RAS unsteady flow component was employed for routing the discharge hydrographs through the modeled river network. Flood inundation maps, as well as longitudinal water surface elevation and channel velocity profiles were generated for the study reaches. As part of the flood inundation study, an uncertainty quantification analysis was carried out on the boundary roughness of the floodplains. The objective was to measure the extent to which flood inundated areas, water surface elevations, and channel velocities were influenced by variations on this empirically-based model coefficient. Finally, the impact of various hydraulic characteristics of the modeled river on the sediment transport process is examined. This characterization is intended to provide a better understanding of a subsequent sediment transport modeling effort to be performed under severe flooding conditions. / Master of Science

O processo de urbanização vem ocorrendo na maioria das cidades brasileiras de forma desorganizada. Desse modo, um problema recorrente que afeta diversos municípios brasileiros são as inundações. A falta de um planejamento que levasse em consideração a drenagem urbana no início do desenvolvimento das cidades acaba criando condições para que as inundações sejam deflagradas a cada época chuvosa. Assim, mostra-se necessária a planificação de medidas preventivas e corretivas que abordem essa questão, a fim de que os prejuízos causados pelas inundações sejam minimizados. Dessa forma, a modelação hidrológica aparece como uma poderosa ferramenta, ao tornar possível uma análise das medidas de controle, através da criação de cenários e simulação de eventos hidrológicos. Nesse contexto o presente trabalho tem como objetivo analisar, por meio de simulação hidrológica e hidráulica, o desempenho de algumas medidas de controle de inundação, estruturais e não-estruturais. Para tanto, com o auxílio do programa ArcGIS 9.3 e imagens de satélite de alta resolução, a bacia hidrográfica do Córrego do Gregório, em São Carlos SP, foi digitalizada e foram criados cenários alternativos que incorporaram as medidas de controle. Através da utilização dos softwares HEC-HMS e HEC-RAS foram realizadas as modelações hidráulica e hidrológica, utilizando tempos de retorno de 25, 50 e 100 anos para a chuva de projeto. Com os resultados obtidos (hidrogramas de cheia e manchas de inundação referentes a cada tempo de retorno), foi possível analisar as medidas comparando-se os diferentes cenários, e concluiu-se, para este caso, que os melhores resultados correspondem à associação das medidas estruturais e não-estruturais. Contudo, também foi verificado que, mesmo com a concretização do cenário mais favorável, o problema das inundações não seria satisfatoriamente equacionado, o que revela a necessidade de se considerar outras medidas para minimizar os prejuízos decorrentes das inundações, tais como medidas de controle na fonte, seguros contra inundações e sistemas de alerta antecipados. / The urbanization process has taken place in most Brazilian cities in a disorganized way, and floods are a recurring problem that has affected many municipalities. The lack of a planning that takes into account the urban drainage in the early development of the cities creates conditions for floods to occur in every rainy season. Therefore, the planning of preventive and corrective measures is necessary to address this issue in order to minimize the flood damages. Hydrological modeling appears as a powerful tool, as it enables the analysis of the flood management measures through the creation of scenarios and simulations of hydrological events. In this context, this dissertation analyzes the performance of some structural and nonstructural flood control measures by means of hydrologic and hydraulic simulations. The basin of the Gregório Stream, in São Carlos - SP, was scanned and scenarios that incorporate the management measures were created, both with the aid of software ArcGIS 9.3 and highresolution satellite images. Hydraulic and hydrologic modelings were performed by HEC-HMS and HEC-RAS software programs using return periods of 25, 50 and 100 years for the design storm. The results (flood hydrographs and flooding areas for each return period) allowed analyzing the measures by comparing the different scenarios and the best results corresponded to the association of structural and nonstructural measures. However, even by implementing the best scenario, the problem of flooding would not be satisfactorily solved, revealing the need to consider other measures to minimize flood damage, such as runoff source control measures, flood insurance and early warning systems.

O processo de urbanização vem ocorrendo na maioria das cidades brasileiras de forma desorganizada. Desse modo, um problema recorrente que afeta diversos municípios brasileiros são as inundações. A falta de um planejamento que levasse em consideração a drenagem urbana no início do desenvolvimento das cidades acaba criando condições para que as inundações sejam deflagradas a cada época chuvosa. Assim, mostra-se necessária a planificação de medidas preventivas e corretivas que abordem essa questão, a fim de que os prejuízos causados pelas inundações sejam minimizados. Dessa forma, a modelação hidrológica aparece como uma poderosa ferramenta, ao tornar possível uma análise das medidas de controle, através da criação de cenários e simulação de eventos hidrológicos. Nesse contexto o presente trabalho tem como objetivo analisar, por meio de simulação hidrológica e hidráulica, o desempenho de algumas medidas de controle de inundação, estruturais e não-estruturais. Para tanto, com o auxílio do programa ArcGIS 9.3 e imagens de satélite de alta resolução, a bacia hidrográfica do Córrego do Gregório, em São Carlos SP, foi digitalizada e foram criados cenários alternativos que incorporaram as medidas de controle. Através da utilização dos softwares HEC-HMS e HEC-RAS foram realizadas as modelações hidráulica e hidrológica, utilizando tempos de retorno de 25, 50 e 100 anos para a chuva de projeto. Com os resultados obtidos (hidrogramas de cheia e manchas de inundação referentes a cada tempo de retorno), foi possível analisar as medidas comparando-se os diferentes cenários, e concluiu-se, para este caso, que os melhores resultados correspondem à associação das medidas estruturais e não-estruturais. Contudo, também foi verificado que, mesmo com a concretização do cenário mais favorável, o problema das inundações não seria satisfatoriamente equacionado, o que revela a necessidade de se considerar outras medidas para minimizar os prejuízos decorrentes das inundações, tais como medidas de controle na fonte, seguros contra inundações e sistemas de alerta antecipados. / The urbanization process has taken place in most Brazilian cities in a disorganized way, and floods are a recurring problem that has affected many municipalities. The lack of a planning that takes into account the urban drainage in the early development of the cities creates conditions for floods to occur in every rainy season. Therefore, the planning of preventive and corrective measures is necessary to address this issue in order to minimize the flood damages. Hydrological modeling appears as a powerful tool, as it enables the analysis of the flood management measures through the creation of scenarios and simulations of hydrological events. In this context, this dissertation analyzes the performance of some structural and nonstructural flood control measures by means of hydrologic and hydraulic simulations. The basin of the Gregório Stream, in São Carlos - SP, was scanned and scenarios that incorporate the management measures were created, both with the aid of software ArcGIS 9.3 and highresolution satellite images. Hydraulic and hydrologic modelings were performed by HEC-HMS and HEC-RAS software programs using return periods of 25, 50 and 100 years for the design storm. The results (flood hydrographs and flooding areas for each return period) allowed analyzing the measures by comparing the different scenarios and the best results corresponded to the association of structural and nonstructural measures. However, even by implementing the best scenario, the problem of flooding would not be satisfactorily solved, revealing the need to consider other measures to minimize flood damage, such as runoff source control measures, flood insurance and early warning systems.

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2015-10-21T19:45:51Z No. of bitstreams: 2 Tese - FERNANDA POSCH CIAMB - 2015.pdf: 5434344 bytes, checksum: 36b420ce99a173b1c3ac6590942d2829 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-10-22T12:38:06Z (GMT) No. of bitstreams: 2 Tese - FERNANDA POSCH CIAMB - 2015.pdf: 5434344 bytes, checksum: 36b420ce99a173b1c3ac6590942d2829 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-22T12:38:06Z (GMT). No. of bitstreams: 2 Tese - FERNANDA POSCH CIAMB - 2015.pdf: 5434344 bytes, checksum: 36b420ce99a173b1c3ac6590942d2829 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-03-20 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The study began with a technical approach to the development of a methodology to determine the support capacity of urban streams exposed to erosion, based on the identification of the maximum limit flow, without the channel overflowing, as determining factor of drag stress and of processes of production, transport and deposition of sediments. During the first field work stage, we defined a longitudinal section of the Samambaia Stream, located in the city of Goiânia, Goiás State Capital, Brazil, to collect soil samples, perform infiltration tests and monitor the level of variation water, with the HOBO U20 equipment. The laboratory stage consisted of testing of physical characterization of soil and runoff simulation using the Inderbitzen apparatus, to determine sediment production rate. The information obtained in these two phases, together with the data coming from the bathymetric surveys of the cross sections and the topographic survey of margins and of the adjacent areas of said channel have been used as input parameters for the simulation performed with the use of the 1D model Hydrologic Engineering Center - River Analysis System (HEC-RAS), version 4.1, in order to know the support capacity of the Samambaia stream. Then was included in the research problem, an argument involving the social and environmental impacts caused by the activities of Civil Engineering, performing an epistemological reflection, extrapolating the focus exclusively technical, to the assimilation of new insights into the interactions between the Civil Engineer and nature, looking for evidence of a possible change to a paradigm that will contribute to the reduction of urban environmental vulnerability. Thus, qualitative research was carried out through semi-structured interviews with sample composed by by professionals working in the Engineering Civil and at the same time, teachers of federal institutions of higher education, forming new professionals in this area. Data analysis was referenced, especially in the works of Thomas Kuhn and also used the software Web Qualitative Data Analysis (WebQDA), by favoring the structuring and the categorization process. The results indicated that the current model adopted by the Civil Engineering is unable to simultaneously meet the expectation of the population, in relation to better living conditions in urban areas, and respond positively to social and environmental challenges. Up until today, conflicts in face of these challenges, constitute indicators of the appearing of anomalies, however, there isn’t a setup for a paradigmatic crisis. / O estudo sobre a capacidade de suporte de córregos urbanos foi iniciado com uma abordagem técnica para a formulação de uma metodologia capaz de determinar a capacidade de suporte de córregos urbanos sujeitos a processos erosivos, embasada na identificação da vazão máxima limite, sem extravasamento do canal, como parâmetro determinante da tensão de arraste e dos processos de produção, transporte e deposição de sedimentos. Durante a primeira etapa de trabalho de campo, definiu-se um trecho longitudinal do Córrego Samambaia, localizado na Cidade de Goiânia, Capital do Estado de Goiás, Brasil, para se coletar amostras de solos, realizar ensaios de infiltração e monitorar a variação de nível de água, com o equipamento HOBO U20. A etapa de laboratório constituiu-se da realização de ensaios de caracterização física do solo e de simulação de escoamento superficial com o uso do Aparelho de Inderbitzen, para se determinar as taxas de produção de sedimentos. As informações conseguidas nessas duas fases, somadas aos dados provenientes do levantamento batimétrico das seções transversais, e plani-altimétrico das margens e áreas adjacentes do referido canal, foram utilizadas como parâmetros de entrada para a simulação, realizada com o uso do modelo 1D Hydrologic Engineering Center – River Analysis System (HEC-RAS), versão 4.1, de modo a se conhecer a capacidade de suporte do Córrego Samambaia. A análise desses dados fez surgir uma nova problemática: os impactos socioambientais provocados pelas atividades da Engenharia Civil, que acendeu uma reflexão epistemológica, extrapolando o enfoque, exclusivamente técnico, sobre as interações entre o Engenheiro Civil o ambiente, em busca de indícios de uma possível mudança para um paradigma que venha colaborar com a redução da vulnerabilidade socioambiental urbana. Desse modo, foram realizadas pesquisas qualitativas, por meio de entrevistas semiestruturadas com um universo amostral constituído por profissionais atuantes na Engenharia Civil e, ao mesmo tempo, docentes de instituições federais de ensino superior, formadoras de novos profissionais desta área. A análise dos dados foi referenciada, principalmente, nas obras de Tomas Kuhn e, como instrumento de análise foi empregado o software Web Qualitative Data Analysis (WebQDA), por favorecer a organização dos dados e o processo de categorização. Os resultados indicaram que o atual modelo adotado pela Engenharia Civil não é capaz de, simultaneamente, atender a expectativa da população, com relação às melhores condições de vida no meio urbano, e responder, de forma positiva, os desafios socioambientais. Concluimos que os conflitos, perante os desafios ambientais, constituem-se indicadores do surgimento de anomalias, no entanto, não há, ainda, a configuração de uma crise paradigmática.

Submitted by Cláudia Bueno (claudiamoura18@gmail.com) on 2016-01-27T17:33:00Z No. of bitstreams: 2 Dissertação - Kamila Almeida dos Santos - 2015.pdf: 15571589 bytes, checksum: 4409744d6740773c19322b95c96e75cd (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-01-28T11:52:55Z (GMT) No. of bitstreams: 2 Dissertação - Kamila Almeida dos Santos - 2015.pdf: 15571589 bytes, checksum: 4409744d6740773c19322b95c96e75cd (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-01-28T11:52:55Z (GMT). No. of bitstreams: 2 Dissertação - Kamila Almeida dos Santos - 2015.pdf: 15571589 bytes, checksum: 4409744d6740773c19322b95c96e75cd (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-12-10 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The urbanization issues is taking place in Brazilian cities has proved disorganized and thus the floods are becoming a recurring phenomenon. The growth of waterproofing in urban land decreases the amount of infiltrated water in the soil during the rainy season, the rivers might otherwise not conform the water demand in the channels in addition to receive a lot of water runoff In this context the hydrodynamic modeling is an important tool to assess the drainage systems and predict the effects of flooding. This study was applied to the watershed of Ribeirão Anicuns in Goiania, where a considerable part of the basin is in an urban area. Using the hydrodynamic model HECRAS were created various flood scenarios with return periods of 15, 25, 50 and 100 years for the project rainfall; there was aid of a geographic information system, using ArcMap 10.0 to the high-resolution orthophoto city and DEM made from airborne laser scanner, with this material extracted the geometry of the basin. In hydrodynamic modeling crafted the model was run in unsteady flow considering the full Saint Venant equation. In addition to the hydrodynamic modeling was carried out a simulation on the INPE simplified model called HAND, which turned out to be an inexpensive tool, easily accessible and with quality results. With the results obtained (flood hydrograph and flood patches concerning the different return times) flood areas were shown in different scenarios created, and you can compare them. The results showed that the flood spot along the basin have become significantly larger as the return periods grow. In urbanized streams were no major changes than the changes that occurred in streams away from the urban area. Streams that are outside the urbanized area focuses on the alert, they are natural streams and showed that will not support the volume of water resulting from this work. / O processo de urbanização que está ocorrendo nas cidades brasileiras tem se mostrado desorganizado e com isso as inundações estão se tornando um fenômeno recorrente. O crescimento da impermeabilização no solo urbano diminui a quantidade de água infiltrada no solo durante o período de chuva, os córregos não conseguem suprir a demanda da água nos canais, além de receber do escoamento superficial uma grande quantidade. Nesse contexto a modelagem hidrodinâmica é uma ferramenta importante para avaliar os sistemas de drenagens e prever os efeitos da inundação. Dessa forma o presente trabalho foi aplicado na bacia hidrográfica do Ribeirão Anicuns, no município de Goiânia, onde uma parte considerável da bacia se encontra em área urbanizada. Utilizando o modelo hidrodinâmico HEC-RAS foram criados vários cenários de inundação com os tempos de retorno de 15, 25, 50 e 100 anos para a chuva de projeto; houve auxílio de um Sistema de Informações Geográficas, utilizando o programa ArcMap 10.0 a ortofoto do município de alta resolução e o MDT feito a partir de laser scanner aerotransportado, com esse material se extraiu a geometria da bacia hidrográfica. Na modelagem hidrodinâmica trabalhada o modelo foi executardo no regime não permanente, considerando a equação de Saint Venant completa. Além da modelagem hidrodinâmica foi realizada uma simulação no modelo simplificado HAND do INPE, onde se mostrou ser uma ferramenta barata, de fácil acesso e com resultados de qualidade. Com os resultados obtidos (hidrogramas de cheia e manchas de inundação referente aos diferentes tempos de retorno) foram mostradas áreas de inundação nos diferentes cenários criados, sendo possível compara-los. Os resultados mostraram que a mancha de inundação ao longo da bacia se tornaram significativamente maiores a medida que os tempos de retorno cresciam. Nos córregos urbanizados houve mudanças maiores do que as mudanças que ocorreram nos córregos afastados do perímetro urbano. Nos córregos que estão fora da área urbanizada foca o alerta, são córregos naturais e mostraram que não suportarão o volume de água resultante deste trabalho.

Expansion of cities and major infrastructure projects lead to changes in land use and river flows. The probability of flooding is expected to increase in the future as a result of these changes in combination with climate change. Hydraulic models can be used to obtain simulated water levels to investigate the risk of flooding and identify areas that might potentially be flooded due to climate change. Since a model is a simplification of the reality it is important to be aware of a model’s uncertainties. A part of this study is therefore aimed to perform a sensitivity analysis to determine which parameter has the largest impact on the model result and has to be treated more careful and accurately. In this study the 1-dimensional flow model Hydrologic Engineering Center-River Analysis System (HEC-RAS) were assed to simulate predicted water levels within the studied river. Topographic data was used to draw cross sections in Geographic Information Systems (GIS) with additional tools of HEC-GeoRAS, in order to get information about the streams geometry. The purpose of doing a sensitivity analysis was attained by investigating changes of the model results when changing different input parameters. This work is based on a reach along Mora river, in Södertälje, Sweden, as a case study. The sensitivity analysis indicate that the number of cross sections has a significant effect when simulating water levels of low flows and that the absolute error of simulated water levels increases as the average spacing between cross sections increases. The second part of the study aims to examine the effects of climate change and how it will affect water levels for the studied river. The results of the study showed that simulated water levels with flows of 100, 200 and 500 years return periods stay within the river channel and do not indicate flooded areas. The results also showed that a backwater effect due to sea level rise would affect the water levels in the stream up to a specific critical point along the studied reach. The lower reach indicated results to contain more uncertain region, where floodplain delineation changed easily as the number of cross section was changed. It is therefore important to identify the areas where uncertainties can be more critical for the results. Because of the uncertainties associated to the model used, it is important to notice that the results of this work correspond particularly to the case study in Mora River. / Studien genomförs inom Ostlänken, som är den första delsträckan av en ny höghastighetsjärnväg mellan Järna och Linköping. Bebyggelse och stora infrastrukturprojekt kommer förändra markanvändning och flöden i vattendrag. I följd av dessa förändringar, tillsammans med framtidens förändrade klimat, kommer risken för översvämningar kunna öka. För att undersöka riskerna för översvämningar och kartlägga områden som riskerar att översvämmas är en hydraulisk modell ett verktyg som kan användas. Då en modell endast är en förenkling av verkligheten och påverkas av flera olika parametrar är det viktigt att vara medveten om modellers osäkerheter. För att få modellen att efterlikna verkligheten så bra som möjligt kan det vara bra att veta vilka parametrar som har störst inverkan på modellens resultat och som bör bearbetas mer noggrant. Därmed är en del av studiens syfte att göra en känslighetsanalys för att utreda vilka modellparametrar och indata som påverkar modellresultaten, med fokus på att analysera simulerade vattennivåer. Känslighetsanalysen utförs genom en fallstudie över Moraån, där den endimensionella flödesmodellen HEC-RAS används för att beräkna vattendragets vattennivåer. Den andra delen av studiens syfte är att undersöka om hur framtidens klimatförändringar kommer kunna påverka det studerade området. En effekt av framtidens förändrade klimat är stigande havsnivåer som leder till ökad risk för översvämning vid kustnära områden. Till följd av dämningseffekter kommer de stigande havsnivåerna även ge ökade vattennivåer uppströms vattendragen, och beroende på vattendragens egenskaper och geometri kommer vattendrag längs med kusten att påverkas på olika sätt. För att undersöka riskerna för översvämningar i ett framtida klimat har modeller med olika klimatscenarios byggts upp där stigande havsnivåer kombinerats med flöden av varierande återkomsttider.

Eskilstuna har sedan länge varit en industristad vilket har inneburit utsläpp av främst metallföroreningar men även organiska ämnen till Eskilstunaån. Provtagningar har vid upprepade tillfällen gjorts och det har visats att sedimentet i ån innehåller höga halter av förorenande ämnen. Sediment förorenat av miljögifter utgör en risk för både miljön och människors hälsa. Beroende på vilka förhållanden som råder i vattendraget skiljer sig sedimentationshastigheten åt, dels mellan olika vattendrag men den kan också variera inom recipienten vilket gör att det kan finnas särskilda områden där sediment och föroreningar ackumuleras. Det kan vara av vikt att identifiera dessa platser för att minska risken för återsuspension av sedimentet, som sedan kan transporteras vidare nedströms, samt för eventuella framtida åtgärder.  I examensarbetet undersöktes föroreningsspridningen i Eskilstunaån och var ackumulationsbottnar kan förväntas ligga. En sedimenttransportmodell byggdes upp i programmet HEC-RAS med åns batymetri som utgångspunkt. Resultaten från modelleringar analyserades och tolkades med det geografiska informationssystemet ArcGIS och jämfördes med bottens hårdhet samt tidigare utförda sedimentprovtagningar. Sedimenttransportmodelleringen tyder på att området med mest ackumulation finns i Eskilstunaån där den passerar centrum och där åns botten är relativt mjuk. De högsta halterna för majoriteten av de undersökta metallföroreningarna påträffades trots detta längre nedströms där botten, sett till hela ån, inte var utmärkande mjuk men i jämförelse med närliggande platser var den däremot mjuk och relativt djup. En slutsats som kan dras ur detta är att vid lokalisering av ackumulationsbottnar bör vattendragets batymetri analyseras i kombination med bottens hårdhet och det bör göras på kortare sträckor. / Eskilstuna has been an industrial town for a long time which has caused emissions of mostly metal contaminants but also organic substances in to the Eskilstuna river. Samples from the sediment shows high content of some pollutants. Contaminated sediments can cause environmental and health hazards. Therefore, it is of importance to locate accumulation areas in the riverbed to avoid resuspension of the sediment, for preventing further transport downstream, and it may be of use if remediation measures becomes necessary.  In this thesis the distribution of metal contaminants in the Eskilstuna river were investigated and accumulation areas located. A sediment transport model, based on the bathymetry, was implemented in the river analysis system HEC-RAS. The results from the model were later analyzed in the geographical information system ArcGIS and compared to the riverbeds hardness and the sediment samples. The sediment transport model showed an accumulation area in the river where it flows through the city center and the riverbed is relatively soft. The highest concentrations of most pollutants were found further downstream where the riverbed has a higher relative hardness. However, if only the neighbouring areas are compared to this locations the accumulation area is soft with a relative large depth. As a conclusion, one may have to take both bathymetry and the riverbeds hardness into account when locating accumulation areas.

Potvynių problema pastaruoju metu tampa vis aktualesnė, ypač tai gerai matosi Europoje. Per paskutinį dešimtmetį kilę didžiausi potvyniai įtakos turėjau daugiau kaip 0,6 milijardo žmonių (EM-DAT, 2008). 2006 metai per potvynius, paralyžiavusius, kai kuriuos Austrijos, Čekijos, Vokietijos ir Slovakijos rajonus, žuvo mažiausiai 10 žmonių (Lietuvos, 2006). 2007 metais ES priimta potvynių rizikos valdymo direktyva 2007/60/EB (Lietuvos, 2007). Šiame darbe analizuojamas potvynio bangos modeliavimas konkrečioje vietovėje ir teritorijos užtvindymas jei įvyktų užtvankos avarija. Turint tikslą kuo geriau atskleisti ne tik lokalių potvynių problemą, darbe atlikta gan išsami literatūros analizė, kurioje aptarta potvynių susidarymo veiksniai. Pateikti duomenys apie didžiausius potvynius, klimato kaitos, kaip atskiro veiksnio įtaka potvynių susidarymui. Aptarta programinė įranga skirta užliejamai teritorijai nustatyti, užtvankų ir žemės nuošliaužų avarijoms modeliuoti. Siekiant įgyvendinti vieną iš pagrindinių darbo tikslų, su pasirinktu modeliu (HEC-RAS) atliktas Padvarių užtvankos avarijos modeliavimas ir nustatytos užliejamos teritorijos. Remiantis modeliavimo rezultatais ir sudarytu užliejamų teritorijų žemėlapiu pateiktos išvados ir pasiūlymai dėl teritorijos, gyventojų ir kitų objektų apsaugos. Sudarius užliejamos teritorijos žemėlapį pastebėta, kad Padvarių užtvankos avarijos atveju potvynio vandens užliejama teritorija viršija 1% tikimybės potvynio užliejamą teritoriją. Daugelis... [toliau žr. visą tekstą] / The problem of inundation becomes more and more relevant; especially it’s relevance is seen in Europe. There is a submergence of particular localities by inundation wave after the collapse of dam being analyzed in this paper. The aim is to reveal more than the problem of local inundations; in this paper there is a comprehensive literature analysis given as well; the factors of inundations are described. The information about the biggest inundations, the influence of climate change as a single factor causing inundations is presented. The software intended to estimate the affluent territory, to model the accidents of dams and slumps is discussed. Seeking to implement one of the main tasks, the Padvariai dam accident modeling using a chosen model (HEC-RAS) was performed and the affluent territories were estimated. According the results of the modeling and the map of the affluent territories, the conclusions and recommendations regarding the safety of territory, inhabitants and the other objects are presented. By examining created map of the affluent territory it was noticed that in case of the Padvariai dam accident the affluent territory would exceed 1% probability of affluent territory. Many bridges existing in the researched territory would be submerged and the risk of their stability would arise. The four situations analysis was performed and the data was used to present the conclusions regarding probability of the inundation arising in extreme situations, the... [to full text]

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.