A modelagem da dinâmica de solutos no solo tem se mostrado uma ferramenta essencial, pois permite simular cenários e prever impactos ao meio ambiente associados ao manejo inadequado de fertilizantes agrícolas. Na zona radicular das culturas a parametrização do transporte de solutos, bem como a parametrização física do solo, são de difícil determinação tornando a sua modelagem onerosa e imprecisa. Portanto, a presente pesquisa teve como objetivo avaliar a performance do modelo SWAP (Soil, Water, Atmosphere and Plant), em simular a extração da solução do solo pela cultura do milho, em ambiente protegido. O ambiente de estudo ficou restrito à rizosfera da cultura do milho ao longo de seu ciclo de desenvolvimento, mediante a aplicação de uma solução de nitrato de potássio via água de irrigação. Para isso, conduziu-se um experimento em ambiente protegido, cujo cultivo do milho foi feito em 18 lisímetros de drenagem de 500L com plantio de duas covas por lisímetro (plantio em 22/11/2014 e colheita em 22/02/2015). Os valores de umidade volumétrica do solo e de condutividade elétrica da solução do solo foram registrados pela TDR (Time Domain Reflectometry), sendo monitorados em 4 profundidades ao longo da secção transversal das raízes (5, 15, 25 e 35 cm). Também foram monitoradas variáveis agrometeorológicas a fim de se descrever as condições experimentais. Os valores simulados pelo modelo SWAP foram confrontados com os dados observados, registrados pela TDR. A avaliação da performance do modelo foi feita pelo emprego do índice de concordância (Id), índice de avaliação de modelos (E), raíz quadrada média do erro (RMSE) e coeficiente de determinação. Diante dos resultados obtidos, percebeu-se pelo monitoramento agrometeorológico que o ciclo da cultura se deu em condições de anomalias climáticas, isso de certa forma influenciou na extração de água pela cultura. A simulação da extração de água na rizosfera do milho pelo modelo SWAP demonstrou uma satisfatória performance do modelo, o qual apresentou resultado pelos índices de avaliação valores superiores a 0,7 e índices de concordância superiores a 0,9 para todas as camadas monitoradas. O erro quadrático médio foi inferior a 0,009 cm3 cm-3 para todas as camadas, apesar de ter nas camadas mais profundas uma atenuação qualitativa na simulação. O movimento da extração da solução do solo na rizosfera, em especial, nas camadas superficiais apresentaram resultados satisfatórios com índices de avaliação de modelos de 0,659 e 0,596 e índices de concordância de 0,913 e 0,834, respectivamente, para as camadas de 5 e 15 cm de profundidade. Já para as camadas mais profundas não se observou boa aderência do valor simulado aos dados. O coeficiente de extração relativa da solução do solo pelo milho apresentou valor de 16%. Assim, o modelo SWAP mostrou-se satisfatório na simulação do movimento da solução do solo na zona radicular da cultura do milho, mesmo sob condições atmosféricas extremas. Não obstante, seu desempenho foi prejudicado para as simulações em camadas inferiores, onde foi observada uma baixa variação do conteúdo de água e concentração de sais no solo. / The modeling of solute dynamics in soil is an essential tool for simulating scenarios and predicting environment impacts associated with inadequate management of fertilizers. Solute transport parameter and soil physical parameters in the vadose zone are difficult to determine, causing modeling to be expensive and imprecise. This research, therefore, was set up to evaluate the effectiveness of the SWAP (Soil, Water, Atmosphere and Plant) model to simulate soil solution uptake by corn under controlled environmental conditions. The study consisted of applying a potassium nitrate solution in irrigation water to maize rhizosphere throughout its development cycle. The experiment was conducted in a greenhouse, in which maize was planted on 11/22/2014 and harvested on 02/22/2015 in eighteen 500L drainage lysimeters.The soil moisture values and electrical conductivity of soil solution were registered by TDR (Time Domain Reflectometry) at four depths (5, 15, 25 and 35 cm) along the cross-section of the root. Environmental variables were also monitored in order to characterize the experimental conditions. Values simulated by the SWAP model were compared with observed data recorded by the TDR. Model performance was evaluated by the use of the Concordance Index (Id), the Model Assessment Index (E), Root Mean Square Error (RMSE), and Coefficient of Determination. As the experiment was conducted under controlled conditions, the water uptake patterns might not be reflective of uptake patterns under normal weather conditions. The simulation of water extraction in the rhizosphere of corn by SWAP model matched observed values, with indices greater than 0.7 and concordance rates of over 0.9, for all monitored layers. The RMSE was less than 0.009 cm3 cm-3 for all layers. The concentration of extracts of the soil solution in the rhizosphere, in particular in the top two layers, were satisfactorily simulated with model evaluation indexes of 0.659 and 0.596, and concordance rates of 0.913 and 0.834, respectively, for the 5 and 15 cm layers. For the deeper layers, there was little correlation between the observed and simulated value. The relative extraction coefficient of soil solution for corn was 16%. Thus, the SWAP model satisfactorily simulated soil solution movement in the upper layers of the vadose zone of maize, even under extreme weather conditions. However, the model did not perform as well in the lower layers performance was impaired for the simulations in lower layers, which had low variation in the observed water content and salt concentration in the soil.

A modelagem da dinâmica de solutos no solo tem se mostrado uma ferramenta essencial, pois permite simular cenários e prever impactos ao meio ambiente associados ao manejo inadequado de fertilizantes agrícolas. Na zona radicular das culturas a parametrização do transporte de solutos, bem como a parametrização física do solo, são de difícil determinação tornando a sua modelagem onerosa e imprecisa. Portanto, a presente pesquisa teve como objetivo avaliar a performance do modelo SWAP (Soil, Water, Atmosphere and Plant), em simular a extração da solução do solo pela cultura do milho, em ambiente protegido. O ambiente de estudo ficou restrito à rizosfera da cultura do milho ao longo de seu ciclo de desenvolvimento, mediante a aplicação de uma solução de nitrato de potássio via água de irrigação. Para isso, conduziu-se um experimento em ambiente protegido, cujo cultivo do milho foi feito em 18 lisímetros de drenagem de 500L com plantio de duas covas por lisímetro (plantio em 22/11/2014 e colheita em 22/02/2015). Os valores de umidade volumétrica do solo e de condutividade elétrica da solução do solo foram registrados pela TDR (Time Domain Reflectometry), sendo monitorados em 4 profundidades ao longo da secção transversal das raízes (5, 15, 25 e 35 cm). Também foram monitoradas variáveis agrometeorológicas a fim de se descrever as condições experimentais. Os valores simulados pelo modelo SWAP foram confrontados com os dados observados, registrados pela TDR. A avaliação da performance do modelo foi feita pelo emprego do índice de concordância (Id), índice de avaliação de modelos (E), raíz quadrada média do erro (RMSE) e coeficiente de determinação. Diante dos resultados obtidos, percebeu-se pelo monitoramento agrometeorológico que o ciclo da cultura se deu em condições de anomalias climáticas, isso de certa forma influenciou na extração de água pela cultura. A simulação da extração de água na rizosfera do milho pelo modelo SWAP demonstrou uma satisfatória performance do modelo, o qual apresentou resultado pelos índices de avaliação valores superiores a 0,7 e índices de concordância superiores a 0,9 para todas as camadas monitoradas. O erro quadrático médio foi inferior a 0,009 cm3 cm-3 para todas as camadas, apesar de ter nas camadas mais profundas uma atenuação qualitativa na simulação. O movimento da extração da solução do solo na rizosfera, em especial, nas camadas superficiais apresentaram resultados satisfatórios com índices de avaliação de modelos de 0,659 e 0,596 e índices de concordância de 0,913 e 0,834, respectivamente, para as camadas de 5 e 15 cm de profundidade. Já para as camadas mais profundas não se observou boa aderência do valor simulado aos dados. O coeficiente de extração relativa da solução do solo pelo milho apresentou valor de 16%. Assim, o modelo SWAP mostrou-se satisfatório na simulação do movimento da solução do solo na zona radicular da cultura do milho, mesmo sob condições atmosféricas extremas. Não obstante, seu desempenho foi prejudicado para as simulações em camadas inferiores, onde foi observada uma baixa variação do conteúdo de água e concentração de sais no solo. / The modeling of solute dynamics in soil is an essential tool for simulating scenarios and predicting environment impacts associated with inadequate management of fertilizers. Solute transport parameter and soil physical parameters in the vadose zone are difficult to determine, causing modeling to be expensive and imprecise. This research, therefore, was set up to evaluate the effectiveness of the SWAP (Soil, Water, Atmosphere and Plant) model to simulate soil solution uptake by corn under controlled environmental conditions. The study consisted of applying a potassium nitrate solution in irrigation water to maize rhizosphere throughout its development cycle. The experiment was conducted in a greenhouse, in which maize was planted on 11/22/2014 and harvested on 02/22/2015 in eighteen 500L drainage lysimeters.The soil moisture values and electrical conductivity of soil solution were registered by TDR (Time Domain Reflectometry) at four depths (5, 15, 25 and 35 cm) along the cross-section of the root. Environmental variables were also monitored in order to characterize the experimental conditions. Values simulated by the SWAP model were compared with observed data recorded by the TDR. Model performance was evaluated by the use of the Concordance Index (Id), the Model Assessment Index (E), Root Mean Square Error (RMSE), and Coefficient of Determination. As the experiment was conducted under controlled conditions, the water uptake patterns might not be reflective of uptake patterns under normal weather conditions. The simulation of water extraction in the rhizosphere of corn by SWAP model matched observed values, with indices greater than 0.7 and concordance rates of over 0.9, for all monitored layers. The RMSE was less than 0.009 cm3 cm-3 for all layers. The concentration of extracts of the soil solution in the rhizosphere, in particular in the top two layers, were satisfactorily simulated with model evaluation indexes of 0.659 and 0.596, and concordance rates of 0.913 and 0.834, respectively, for the 5 and 15 cm layers. For the deeper layers, there was little correlation between the observed and simulated value. The relative extraction coefficient of soil solution for corn was 16%. Thus, the SWAP model satisfactorily simulated soil solution movement in the upper layers of the vadose zone of maize, even under extreme weather conditions. However, the model did not perform as well in the lower layers performance was impaired for the simulations in lower layers, which had low variation in the observed water content and salt concentration in the soil.

No description available.

Streams and rivers are a vital part of our ecosystem. They are imperiled by human ecological activities such as urbanization, industrialization, and agriculture which discharge excess nitrate and other pollutants into our waterways. Here, this dissertation seeks to understand the physical and biogeochemical processes which attenuate pollutants in stream corridors. The focus is hyporheic zones which form the interface between surface water and groundwater below and adjacent to stream channels, and riparian zones which form the interface between channels and adjacent uplands, both of which can attenuate pollutants. In this context, soil-pipes can dominate subsurface hydraulics. This research first employed MODFLOW and MT3D-USGS to model transient hyporheic hydraulics and nitrate transport in a length of riparian/riverbank soil to probe the effects of soil pipes on hydraulics and denitrification due to peak flow events in the channel. Findings showed that inserting just one soil pipe 1.5 m in length caused a ~75% increase in both hyporheic exchange and denitrification. A rough upscaling showed soil pipes could remove up to ~3% of nitrate along a 1-km reach. Next, the ability of soil pipes to bypass the often championed ability of riparian buffers to remove nitrate migrating from uplands to the channel was evaluated. This effort also employed MODFLOW and MT3D-USGS to simulated hydraulics and nitrate removal along a length of riparian soil. Findings showed that soil pipes increased flow of nitrate to the banks by five orders of magnitude in some cases. We posited a non-dimension parameter which governs when nitrate bypass is significant. In addition to soil pipes, dune bedforms can also enhance hyporheic exchange, primarily in the stream/riverbed. Again employing MODFLOW but now pairing with the transport code SEAM3D to simulate microbially-mediated aerobic metabolism of dissolved organic carbon and dissolved oxygen, the combined effects of dune translation and microbial growth and death were explored. Major findings include that neglecting microbial growth can lead to inaccurate modeling of biogeochemistry, and that aerobic metabolism increased with celerity. The results herein bolster knowledge of natural pollutant attenuation in stream and river corridors, and have implications for pollutant mitigation strategy and stream credit allocation. / Doctor of Philosophy / Streams are a vital part of our ecosystem. They are imperiled by human ecological activities such as urbanization, industrialization, and agriculture which discharge nitrate and other pollutants into our waterways. Here, this dissertation seeks to understand the physical and biological processes which attenuate pollutants. The hyporheic zone is the interface between surface water and groundwater below the bed and adjacent to stream banks, and can attenuate pollutants. Transient peak flow events such as a storm or snow melt raise the stream water levels, causing the water pressure in the stream channel to temporarily outweigh the water pressure in the soil pore spaces adjacent to the stream channel. This drives water into the banks subjecting it to pollutant attenuation processes. Soil pipes (long cylindrical void spaces created by decayed plant roots) are prevalent along stream banks, and they dominate subsurface hydraulics. This dissertation implemented a numerical study on a chunk of riparian soil to probe the effects of soil pipes on hydraulics and denitrification. Findings showed that inserting just one – 1.5 m soil pipe caused a ~75% increase in both water flow volume into the bank and nitrate removal. Riparian buffers are the vegetated strips adjacent to stream channels and have long been championed as stalwarts of pollutant removal. Soil pipes undermine this by acting as a bypass mechanism. A numerical study was again performed on a chunk of riparian soil to quantify the effects soil pipes on riparian bypass of nitrate. Findings showed that soil pipes increased flow of nitrate to the banks by five orders of magnitude in some cases. This means that a buffer enhancement strip with fine roots that prevent the formation of soil pipes should be installed along riparian buffers. In addition to soil pipes, dune bedforms can increase flowrate of water into the hyporheic zone. This dissertation modeled the combined effects of dune translation and microbial growth and death. Major findings include that neglecting microbial growth can lead to inaccurate modeling of biogeochemistry, and that biodegradation increases with increased dune velocity. The results herein bolster knowledge on natural pollutant attenuation in streams, and have implications in terms of pollutant mitigation strategy and stream credit allocation.

Submitted by Yane de Freitas da Silva null (yanefsilva@gmail.com) on 2018-01-31T21:39:19Z No. of bitstreams: 1 dissertacao_definitivo_rev1.pdf: 1799376 bytes, checksum: 8947ebad31af38685cffc48c54262414 (MD5) / Rejected by Karina Gimenes Fernandes null (karinagi@fcav.unesp.br), reason: Solicitamos que realize a correção na submissão seguindo as orientações abaixo: - Inserir certificado de aprovação e ficha catalográfica. Após a inserção desses itens obrigatórios, salve em pdf editável com um nome diferente do primeiro e refaça o autoarquivamento. Agradecemos a compreensão on 2018-02-02T13:13:02Z (GMT) / Submitted by Yane de Freitas da Silva null (yanefsilva@gmail.com) on 2018-02-05T16:23:48Z No. of bitstreams: 1 Yane_Freitas_Silva.pdf: 1871755 bytes, checksum: 04ff93edd037320b2085f330f1d6bea0 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-02-07T15:40:40Z (GMT) No. of bitstreams: 1 silva_yf_me_jabo.pdf: 1871755 bytes, checksum: 04ff93edd037320b2085f330f1d6bea0 (MD5) / Made available in DSpace on 2018-02-07T15:40:40Z (GMT). No. of bitstreams: 1 silva_yf_me_jabo.pdf: 1871755 bytes, checksum: 04ff93edd037320b2085f330f1d6bea0 (MD5) Previous issue date: 2018-01-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A soja é uma das culturas mais importante na economia mundial, originária de clima temperado, adapta-se bem em uma faixa de 20 a 35 ºC e a necessidade total de água para a cultura é em torno de 800 mm/ciclo, dependendo das condições climáticas, manejo da cultura e duração do ciclo. O conhecimento sobre a temperatura de superfície, o saldo de radiação e a evapotranspiração da cultura em cada fase fenológica é a base para o dimensionamento de sistemas de irrigação e gerenciamento eficiente da água. Desse modo, o objetivo do trabalho foi estimar o albedo de superfície, o NDVI, o saldo de radiação, a temperatura de superfície e a evapotranspiração real da soja, aplicando o algoritmo “Simple Algoritmo Model For Evapotranspiration Retrieving” - SAFER comparado com o método FAO 56, fazendo uso de técnicas de sensoriamento remoto e das variáveis climáticas obtidas em estação agrometeorológica. Constatou-se que o valor médio do albedo de superfície calculado pelo SAFER para todo o ciclo da soja foi de 18%. As áreas com valores de NDVI próximos a 0,8 espera-se maiores produtividades, podendo ser gerados mapas que auxiliarão de forma qualitativa. A temperatura de superfície estimada pelo SAFER apresentou valores bem próximos aos medidos pela estação agrometeorológica. Os maiores valores de saldo de radiação foram encontrados nas fases de pleno desenvolvimento, enquanto que os menores ocorreram em fase próxima a colheita e solo exposto. A ETr média estimada pelo SAFER apresentou redução de 1,91 mm dia-¹ comparada com o método FAO 56. / Soybean is one of the most important crops in the world economy, coming from temperate climate, well adapted in a range of 20 to 35 °C and the total water requirement for the crop is around 800 mm/cycle, depending on the climate conditions, crop management and cycle duration. Knowledge about surface temperature, radiation balance and evapotranspiration of the crop in each phenological phase are the basis for the operation of water efficient irrigation systems. Thus, the objective of this work was to estimate the surface albedo, the NDVI, the balance of radiation, the surface temperature and actual evapotranspiration of soybean applying the algorithm “Simple Algorithm Model For Evapotranspiration Retrieving” - SAFER compared to model FAO 56, using remote sensing techniques and of the climatic variables obtained in agrometeorological station. It was observed the average value of the surface albedo calculated by SAFER for the entire soybean cycle was 18%. Areas with NDVI values close to 0.8 expected higher yields, and maps can be generated that will help in a qualitative way. The surface temperature estimated by SAFER was very close to that measured by the agrometeorological station. Analyzed only by phenological phases, the highest values of radiation balance were found in the phases of full development while the smaller ones, in the near phase the harvest and exposed soil. The mean ETr estimated by SAFER presented a reduction of 1.91 mm day¹ compared to the FAO 56 method. / CAPES 50100009

Syfte med examensarbetet har varit att upprätta en grundvattenmodell överEnköpingsåsen med hjälp av programvaran MODFLOW för att därefter försöka skattagrundvattenmagasinets parametrar. Parameterskattningen utfördes med detmodelloberoende programmet PEST. Parallellt med detta gjordes även enpumptestutvärdering av dessa parametrar där typkurvor passades till en tidigare utfördprovpumpning av akviferen. Därefter jämfördes dessa båda metoder. Vidare utfördesäven en känslighetsanalys av grundvattenmodellen i MODFLOW för att försökalokalisera nya undersökningsplatser.Grundvattenmodellen uppfördes över Enköpingsåsen i och kring Enköping. Där är åsenlokaliserad i nord sydlig riktning och strax söder om Enköpings centrala delar korsasåsen av Enköpingsån. Det råder osäkerhet angående grundvattenmagasinetsvattenbalans och var åsen får sitt tillskott av vatten ifrån. Enköpingsåsen fungerar somhuvudvattentäkt i Enköpings stad vilket gör att detta har ansetts viktigt att utreda.Grundvattenmodellen byggdes upp genom att främst använda redan insamlad data frångeotekniska, geofysiska och hydrogeologiska undersökningar utförda i området samtdata från SGU och SMHI. Därifrån togs data om områdets uppbyggnad och struktursamt dess yttre betingelser som till exempel nederbörd och Mälarens vattenstånd för attskapa en numerisk modell i MODFLOW.Resultaten visar på ett överensstämmande resultat mellan parameterskattningen gjord iMODFLOW och pumptestutvärderingen. Vidare tyder resultaten i MODFLOW på attde största osäkerheterna i modellen ligger kring Enköpingsån och är då beroende av omvattnet tillförs från grundvattenmagasinets laterala delar eller från Enköpingsån.Känslighetsanalysen tyder även på att för ytterligare undersökningar av åsenshydrogeologiska betingelser bör fokus ligga på förhållandena i Enköpingsåns sedimentoch dess genomsläpplighet. / The purpose of this thesis is to establish a groundwater model of the Enköping eskerusing MODFLOW simulation and then estimate groundwater parameters with themodel-independent program PEST. In parallel, a pump test evaluation of theseparameters where type curves are fitted to a previously performed pump test of theaquifer is done to estimate the aquifer parameters. Eventually, these two methods arecompared. Furthermore, a sensitivity analysis of the groundwater model is performed totry to locate additional measurement points.The groundwater model was built for the Enköping esker in and around Enköping. Theesker is located in the north-south direction and just south of Enköpings central partswhere Enköpingsån crosses the esker. There is uncertainty regarding the water balanceof the aquifer and where the esker recharges its water from. Enköping esker serves asthe main water source in Enköping city and this is why it is considered important toinvestigate.The groundwater model was constructed primarily by using already collected data fromgeotechnical, geophysical and hydrogeological studies conducted in the area as well asdata from the SGU and SMHI. The data on the area's composition and structure as wellas its external conditions is taken to create a numerical model in MODFLOW.The results show consistent outcomes between parameter estimates made withMODFLOW/PEST and the pump test evaluation.The results made with MODFLOW makes it possible to do further analysis. Resultsshow large model uncertainties around Enköpingsån and the esker is dependent onwater supplied from either the groundwater aquifer’s lateral parts or Enköpingsån. Thesensitivity analysis also suggests that further studies of the hydrogeological conditionsshould be concentrated to Enköpingsån’s sediments and its water penetration capacity.

Density functional theory is the most commonly used computational tool to study properties of solids and molecules. Self-interaction error, that arises due to improper cancellation of the self-Hartree and the self exchange correlation energy, has long been identified as a major limitation of practical density functional approximations. We develop and test the performance of different self-interaction corrected functionals in accurately predicting a wide range of properties. This work focuses on use of the Fermi-L\"{o}wdin orbital self-interaction correction (FLOSIC) method to study neutral water complexes and interaction of ions with water clusters. The strongly constrained and appropriately normed (SCAN) density functional approximation (DFA) has been found to give the correct energy ordering of low-lying isomers of water hexamers, resolves the density anomaly between water and ice, and improves the relative lattice energy of ice polymorphs and the infrared spectra of liquid water. However, SCAN is not without its drawbacks. The binding energies of water clusters and lattice energies of ice phases are overestimated by SCAN. We find that by explicitly removing the self-interaction error, the hydrogen-bond binding energy of water clusters can be significantly improved. In particular, self-interaction correction to the SCAN functional (FLOSIC-SCAN) improves binding energies without altering the correct energetic ordering of the low-lying water hexamers. So, orbital-by-orbital removal of self-interaction error applied on top of a proper DFA can lead to an improved description of water complexes. To gain further insight into the performance of different functionals on the relative stability of water clusters, we decompose the total interaction energy into many-body components. We see that the major portion of error in SCAN comes from the two-body interaction, and the FLOSIC-SCAN improves two-body interactions over SCAN and predicts higher-order many-body interactions with about the same accuracy as SCAN. The SCAN functional gives good account of monomer deformation energy (one-body energy), PBE estimated it too low and self-interaction corrected methods FLOSIC-PBE and FLOSIC-SCAN estimated too high monomer deformation energies. Improvement in the total interaction energy by FLOSIC-PBE and FLOSIC-SCAN is happening because of error cancellation by one-body interaction energy. Aqueous solutions of ions are of particular interest due to their profound applications in environmental chemistry, solvation mechanics, the desalination process, etc. This motivated us to study ion-water systems, which include hydronium ion-water clusters, hydroxyl ion-water clusters, halide ion-water clusters, and alkali ion-water clusters. The erroneous delocalization of the extra-electron in anions obtained with DFAs is basis-set dependent. DFAs like LSDA, PBE, or SCAN can bind only a fraction of the excess electron in the complete basis set limit, implying that a moderate-sized localized basis would be a good choice for them. But, accurate description of hydrogen bonds often requires a large basis with some extra diffuse functions. So, in negatively charged hydrogen-bonded systems like deprotonated water clusters, the suitable choice of basis-set is both difficult and ambiguous. We explore this issue systematically in this work. Further, we have found that the better performance by application of FLOSIC is seen in all systems that are connected at least with one hydrogen bond and the error in the binding energy decreases with increase in the size of an ion or equivalently decreases with the length of the hydrogen bond. Moreover, within the same ion-water system, error in the binding energy decreases with increase in the size of the cluster. Non-hydrogen-bonded water-alkali clusters are not affected by the self-interaction errors. / Physics

Ce travail porte sur les processus hydrodynamiques en zone littorale.Deux principaux thèmes sont abordés. Le premier concerne la couchelimite oscillante provoquée par l’interaction entre les vagues et le fondà l’approche des côtes. Le second traite de l’évolution de la circulationet la vorticité induite par la bathymétrie et/ou le forçage des vagues.Un modèle de couche limite turbulente a été élaboré et utilisé pourobserver l’évolution de la couche limite oscillante sous l’effet de vaguesnon-linéaires, en s’appuyant sur une modélisation physique menéedans le canal à houle du LEGI. Les profils expérimentaux de vitesseet positions du fond fixe instantanés permettent de définir l’évolutiondes non-linéarités induites par les vagues au sein de la couche limite.Le modèle numérique couplé à une modélisation du mouvement dulit mobile est capable de reproduire l’évolution de ces non-linéarités,et explique que la diffusion verticale observée expérimentalementest principalement due au mouvement vertical du lit causé induitpar les vagues. Pour l’étude de la circulation et de la vorticité enzone côtière, un modèle numérique 2D moyenné sur la verticale detype Shallow Water est validé avec les données d’une expériencemenée dans le basin à vagues du Laboratoire Hydraulique de France(ARTELIA). La formation de courants sagittaux a été forcée parun front de vagues avec un déficit d’énergie au centre du bassin. Lemodèle numérique est validé par des mesures de surface libre, devitesse, ainsi que de circulation et vorticité. En utilisant ensuitel’équation de vorticité potentielle comme outil de diagnostic, avec unforçage monochromatique on prédit un équilibre entre la générationde vorticité et son advection par l’écoulement moyen. / This work is about the hydrodynamic processes in the nearshorezone. They are of great importance to estimate the overall dynamicsof the coastal zone. This thesis is divided into two main parts; thefirst one investigates the coastal bottom boundary layer induced bythe interaction of the waves and the bottom when approaching thecoast; the second one is about the evolution of the mean circulationand vorticity induced by an inhomogeneity in the bathymetry orthe wave forcing. A turbulent boundary layer numerical model hasbeen developed and used to simulate the evolution of the oscillatingboundary layers under non-linear waves, of a flume experiment at theLaboratoire des Ecoulements Géophysiques et Industriels (LEGI) inGrenoble, France. The experimental instantaneous velocity profilesand still bed positions, allow defining the non-linear velocity distributionsinduced by the waves within the boundary layer. The numericalmodel coupled with a ad-hoc modeling of the mobile bed motionis able to reproduce the vertical distribution of the non-linearities,and also indicates that the vertical diffusion observed experimentallyis mainly caused by the mobile bed motion induced by the passingwaves. A 2D depth-averaged nonlinear shallow water numericalmodel is used to study the circulation and vorticity in the nearshorezone. This model is validated on a mobile bed experiment in thewave basin of the Laboratoire Hydraulique de France (ARTELIA).The formation of rip currents is forced by a damped wave forcing inthe middle of the wave basin. The numerical model is validated withfree surface and velocity measurements, and by the circulation andvorticity. Using the potential vorticity balance as a diagnosis tooland with a monochromatic wave forcing, an equilibrium between thevorticity generation and advection is observed in the nearshore zone. / Este trabajo trata de los procesos hidrodinámicos en la zona litoral,de grande importancia para la dinámica global del flujo costero. Dostemas principales son estudiados. El primero trata de la capa límiteoscilante provocada por la interacción entre el oleaje y el fondo alacercarse a la costa. El segundo tema trata de la evolución de lacirculación y la vorticidad inducida por la batimetría y/o el oleaje.Un modelo de capa límite turbulenta ha sido elaborado y validadopara analizar la evolución de la capa límite oscilante bajo la influenciade oleaje no-lineal, apoyándose en una modelación física, realizada enel canal de olas del LEGI. Los perfiles experimentales instantáneos develocidad y posición del fondo fijo, permiten definir la evolución delas no-linealidades inducidas por las olas dentro de la capa límite. Elmodelo numérico acoplado a una modelación del movimiento del fondomóvil es capaz de reproducir la evolución de estas no-linealidades, yexplica también que la difusión vertical observada experimentalmentees principalmente debida al movimiento vertical del fondo inducidopor el oleaje. El estudio de la circulación y de la vorticidad en zonascosteras se hace mediante un modelo numérico 2D promediado enla vertical de tipo Shallow Water que es validado con los datos deuna experiencia llevada a cabo en la piscina de olas del LaboratoireHydraulique de France (ARTELIA). La formación de corrientes ripse realiza a través de frentes de olas con un déficit de energía en elmedio de la piscina. El modelo numérico es validado con medicionesde superficie libre, de velocidades, y de circulación y vorticidad.Utilizando la ecuación de vortcidad potencial como herramienta dediagnóstico, con un oleaje monocromático se predice un equilibrioentre la generación de vorticidad y su advección por las corrientes.