Extensive research has been undertaken to improve the robustness of runoff quantity predictions for urban catchments. However, equally robust predictions for runoff quality have yet to be attained. Past studies addressing this issue have typically been confined to the use of simple conceptual or empirical models which forgo the tedious steps of providing a physical representation of the actual system to be modelled. Consequently, even if the modelling results for the test catchments are satisfactory, the reliability and applicability of these models for other catchments remain uncertain. It is deemed that by employing process-based, deterministic models, many of these uncertainties can be eliminated. A lack of understanding of the hydrological processes occurring during storm events and the absence of good calibration data, however, hamper the advancement of such models and limit their use in the field. This research proposes that the development of a hydrologic model based on the kinematic wave equations linked to an advection-dispersion model that simulates pollutant detachment and transport will improve both runoff quantity and quality simulations and enhance the robustness of the predictions. At the very worst, a model of this type could still highlight the underlying issues that inhibit models from reproducing the recorded historical hydrographs and pollutographs. In actual fact, this approach has already been applied by various modellers to simulate the entrainment of pollutants from urban catchments. Also, the paradigm shift to using the Water Sensitive Urban Design (WSUD) approach in designing urban stormwater systems has prompted the need to differentiate the various sources of pollutants in urban catchments such as roads, roofs and other impervious surfaces. The primary objective of the study reported herein is to model runoff quantity and quality from small urban catchments, facilitated by the procurement of the necessary field data to calibrate and validate the model via implementation of a comprehensive field exercise based in Sydney. From a water quality perspective, trace metals were selected as the foci. The study outcomes include the formulation of a linkage of models capable of providing accurate and reliable runoff quantity and quality predictions for the study catchments by taking into consideration: - The different availability of pollutants from urban catchments, i.e. roads vs. roofs; - The build-up characteristics of pollutants on the distinct urban surfaces and their spatial distribution; - The contribution of rainwater to urban runoff pollution; - The partitioning of pollutants according to particulate bound and dissolved phases; - The respective role of rainfall and runoff in the detachment and entrainment of pollutants; - The influence of particle properties such as particle size distribution and density on pollutant transport; and - The relationship associating particulate bound metals to suspended solids. The simulation results obtained using the proposed model were found to be suitable for modelling the detachment and transport of pollutants for small urban catchments. Interpretation of these results reveals several key findings which could help to rectify shortcomings of existing modelling approaches. Even though the robustness of the model presented here may not translate into a significant improvement in the overall robustness of model predictions, the physical basis on which this process-based model was developed nevertheless provides the flexibility necessary for implementation at alternative sites. It is also shown that the availability of reliable runoff data is essential for implementation of the model for other similar urban catchments. In conclusion, the proposed model in this study will serve as a worthy tool in future urban catchment management studies.

Les vagues de surface générées par le vent, généralement appelées houle ou mer de vent, sont omniprésents à la surface de I'océan. Ils sont et ont des périodes variant entre 2 et 25 secondes et de longueur d'onde variant de quelques mètres à plusieurs centaines de mètres. Il existe aussi des ondes plus longues et, à plus basse fréquence appelés ondes infragravitaires (IG), qui sont associés aux vagues courtes, générées par le vent. Ces ondes ont des périodes dominantes comprise entre 30 secondes et 10 minutes et, quand ils se propagent librement, avec des longueurs d'ondes pouvant atteindre plusieurs dizaines de kilomètres. En dehors de la zone de surf, I'amplitude verticale de ces ondes infragravitaires est de I'ordre de 1 à 10 cm, tandis que I'amplitude des vagues courtes est de I'ordre de 1-10 m.Malgré leurs petites échelles d'amplitude, ces ondes infragravitaires peuvent avoir une importance non-négligeable dans certaines situations. Elles peuvent par exemple exciter des phénomènes de seiches dans les ports et mettre en résonance des structures en mer et des lames de glaces dansI'Arctique ou I'Antarctique. Le champ d'ondes infragravitaires constituera probablement aussi une fraction significative du signal mesuré par la future mission du satellite Surface Water Ocean Topography (SWOT). Ce champ d'onde infragravitaire devra être caractérisé pour atteindre la précision attendue sur les mesures de hauteur de mer dynamiques. Il est probable que la précision visée ci-dessus ne soit pas possible pour les forts états de mer avec de longues houles. L'un des objectifs de cette thèse était de fournir une première quantification de ces incertitudes associées.Au-delà de la mission SWOT, la quantification du champ d'ondes IG est un problème clé pour la compréhension de plusieurs autres phénomènes géophysiques tels que la compréhension des microséismes. / Wind-generated surface gravity waves are ubiquitous at the ocean surface. Their period varies between 2 and 25 seconds, with wavelength varying between a few meters to several hundreds of meters. Longer and, lower frequency surface gravity waves, called infragravity (IG) waves, are associated to these short, high frequency wind-generated waves. These infragravity waves have dominant periods comprised between 30 seconds and 10 minutes, and, when they propagate freely, with horizontal wavelengths of up to tens of kilometres, as given by the linear surface gravity wave dispersion relation. Outside of surf zones, the vertical amplitude of these infragravity waves is of the order of 1-10 cm, while the amplitude of wind-generated waves is of the order of 1-10 m.Given the length scales of the infragravity wavelengths, and despite the fact that the infragravity wave field exhibits much smaller vertical amplitudes than the high frequency wind-driven waves, the infragravity wave field will be a significant fraction the signal measured by the future Surface Water Ocean Topography satellite (SWOT) mission. This infragravity wave field will have to be characterized in order to achieve the expected precision on dynamic height measurements. It appears likely that the above mentioned precision will not be feasible for high sea states and long and steep swells. One of the aims of this thesis was to provide a first quantification of these associated uncertainties. Beyond the SWOT mission, the quantification of the IG wave field is a key problem for the understanding of several geophysical phenomena, such as the understanding of microseisms and ice shelves break up.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第17869号 / 工博第3778号 / 新制||工||1578(附属図書館) / 30689 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 寶 馨, 教授 細田 尚, 准教授 立川 康人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Wave models are an integral part of coastal engineering due to their ability to quantify information that is either unobtainable or unavailable. However, these models rely heavily on the input of a directional wave spectrum that describes the variation of energy with frequency and direction. This study investigated how five methods for computing the directional wave spectrum perform within the nearshore spectral wave model, STWAVE. The results of the five experimental runs showed that overall, the greatest differences between spectra were observed in the significant wave height parameter. The mean wave direction showed greater differences at the offshore model domain boundary and lesser differences as the wave enters the nearshore; and the peak period had fewer differences at the boundary, but at the nearshore the differences were dependent upon the presence of wind forcing. Winds had a significant impact on observed differences between the spectra in the domain by dominating the wave field variation.

Wave heights and periods of surface waves in the Baltic Sea have been modelled for a two-year period (1999-2000) with the wave model Hypas on an 11x11-km grid scale. There is a clear seasonal variation with higher waves during winter and lower during summer. This is mainly a reflection of the wind climate in the area where the winters are windier than the summers. The largest waves are found in the Skagerrak and over the deeper, eastern areas in the Baltic Proper. In the Baltic Sea, the surface waves influence the bottom sediment by initiating resuspension down to 80 m depths. This process is dependent not only on the waves but also on the varying grain size diameters. Fine and medium sand resuspend more often than other sediment types, and these sediments cover together about 25% of the Baltic Proper area. On average sediment is here resuspended 4-5 times per month with a duration for each event of 22 hours. The highest resuspension frequencies are found on the eastern and southern side of the Baltic Proper. During resuspension sediment grains are lifted up into the water mass and matters earlier bound in the sediment can be released. This may stimulate both production and degradation of organic matter.

The capability to observe ocean swell using spaceborne Synthetic Aperture Radar (SAR) has been demonstrated starting with ERS-1 mission in 1992. This dissertation shows how ocean swell properties can be used to combine swell observations of heterogeneous quality and acquired at various times and locations for the observation and forecast of ocean swell fieldsusing ASAR instrument on-board ENVISAT. The first section is a review of how ocean swell spectra can be derived from the SAR complex images of the ocean surface using a quasi-linear transformation. Then, significant swell heights, peak periods and peak directions from in situ measurements are used to assess the accuracy of the SAR observed swell spectra. Using linear propagation in deep ocean, a new swell field reconstruction methodologyis developed in order to gather SAR swell observations related to the same swell field. Propagated from their generation region, these observations render the spatio-temporal properties of the emanating ocean swell fields. Afterwards, a methodology is developed for the exclusion of outliers taking advantage of the swell field consistency. Also, using the irregularly sampled SAR observations, quality controlled estimations of swell field integral parameters are produced on a regular space-time grid. Validation against in situ measurements reveals the dramatic impact of the density of propagated observations on the integral parameters estimated accuracy. Specifically, this parameter is shown to be very dependent on the satellite orbit. Finally, comparisons with the numerical wave model WAVEWATCH-III prove it could potentially benefit from the SAR swell field estimates for assimilation purposes.

In this study, the evolution of the numerical water wave models with the theoretical background and the governing equations are briefly discussed and a numerical model MIKE21 BW which can be applied to wave problems in nearshore zone is presented. The numerical model is based on the numerical solution of the Boussinesq type equations formulated on time domain. Nonlinearity and frequency dispersion is included in the model. In order to make comparison between the results of nonlinear shallow water equations with Boussinesq terms, MIKE21 BW and NAMIDANCE are applied to the problem of wave propagation in the long distances and runup on simple and composite slopes. The numerical experiments are applied to Dat&ccedil / a Marina and the results are compared to the results of the physical experiments on wave disturbance in Dat&ccedil / a Marina. In these comparisons the reflection characteristics of different coastal boundaries in the harbor area are tested and the internal parameters in the model are calibrated accordingly. The numerical model MIKE21 BW is applied to skenderun harbor as a case study. The input wave parameters are selected from the wave climate study for Iskenderun Harbor. The model is set up and the agitation inside the harbor is computed according to four different incoming wave scenarios. The disturbance maps inside the harbor for different incoming wave scenarios are obtained. The critical regions v of the harbor according to disturbance under different wave conditions are presented and discussed.

L’imagerie satellite radar propose un point de vue intéressant pour l’étude et la compréhension des océans. Là où l’altimétrie, reconnue et utilisée mondialement, a su s’imposer comme une source de données majeure, les observations de houle issues du SAR (de l’anglais « Synthetic Aperture Radar ») restent encore largement sous exploitées. L’objet de cette thèse est de promouvoir l’utilisation de ces données en proposant un modèle pour l’analyse et la prévision de la houle à l’échelle du globe qui soit indépendant des modèles numériques classiques comme Wavewatch-III. Ce travail s’inscrit dans une logique de pérennisation de la mesure de houle depuis l’espace avec le lancement dans les trois années à venir des trois missions satellites Sentinel-1 A et B et CFOSAT. Un des principaux résultats de ce travail est la capacité de la méthode développée à fournir une information plus précise que celle des modèles existants. Cette méthode permet également une meilleure caractérisation des mesures utilisées en entrée et des pistes d’amélioration de ces dernières sont dégagées pour les futures activités de calibration/validation. Ces travaux ouvrent également des perspectives sur les possibilités d’assimilation des sorties de ce nouveau modèle dans les modèles numériques classiques. / The capability to observe ocean swell using spaceborne Synthetic Aperture Radar (SAR) has been demonstrated starting with ERS-1 mission in 1992. This dissertation shows how ocean swell properties can be used to combine swell observations of heterogeneous quality and acquired at various times and locations for the observation and forecast of ocean swell fieldsusing ASAR instrument on-board ENVISAT. The first section is a review of how ocean swell spectra can be derived from the SAR complex images of the ocean surface using a quasi-linear transformation. Then, significant swell heights, peak periods and peak directions from in situ measurements are used to assess the accuracy of the SAR observed swell spectra. Using linear propagation in deep ocean, a new swell field reconstruction methodologyis developed in order to gather SAR swell observations related to the same swell field. Propagated from their generation region, these observations render the spatio-temporal properties of the emanating ocean swell fields. Afterwards, a methodology is developed for the exclusion of outliers taking advantage of the swell field consistency. Also, using the irregularly sampled SAR observations, quality controlled estimations of swell field integral parameters are produced on a regular space-time grid. Validation against in situ measurements reveals the dramatic impact of the density of propagated observations on the integral parameters estimated accuracy. Specifically, this parameter is shown to be very dependent on the satellite orbit. Finally, comparisons with the numerical wave model WAVEWATCH-III prove it could potentially benefit from the SAR swell field estimates for assimilation purposes.

Internal waves (IWs) owe their existence to the stratification in the medium. These waves affect acoustic transmission greatly. Impact of these waves on acoustic transmission in deep water is fairly well understood due to better performance of well-celebrated Garrett-Munk (GM) model. However, in shallow waters, predicting these waves is not as easy, because of interactions with the bottom and surface. Hence two experiments, one during October 2002 and the other during October 2004 were conducted to characterize IWs in the shallow waters of northeastern Arabian Sea. The first experiment was carried out during October 2002 south of Gulf of Kutch (GOK) and the second experiment during October 2004 both south and north of GOK. During these experiments CTD moorings were deployed and temperature and salinity (TS) data were collected at 5 seconds interval. CTD Yo-Yo collected vertical profiles of TS at a sampling interval of 2.5 minutes for 3.5 hours during October 2002 and 1 hour during October 2004 experiment. In addition, during the first experiment, currents were measured using a vessel mounted Acoustic Doppler Current Profiler (ADCP), and in both experiments CTD TS profiles were taken from the ship. This data set has been used for characterizing internal waves in the northeastern Arabian Sea. Experiment conducted during October 2002, south of GOK has revealed large tidal ranges. The barotropic tidal range at the experimental site was 1.5m. Current observations made using the vessel mounted ADCP, along the shore and across the shore, showed signs of first mode (baroclinic) oscillations; currents in the top and bottom layers were in opposing directions. They were found to be southwesterly in the top layer and northeasterly in the bottom layer. Time - depth sections of TS profiles from CTD yo-yo data, revealed the presence of high frequency internal waves and solitons overriding on low frequency trend. Moored CTD time series of temperature records showed the presence of internal solitons, which caused a vertical displacement of about 8m in the isotherms, which is equivalent to 3OC change in temperature, in less than 10 minutes. Passage of internal solitons induced vertical mixing causing the mixed layer to deepen by about 10m and current speed increased by about 0.1 m/s. Internal solitons were traveling towards northwest and current vectors suggest that they were generated when the internal tide is reflected from the bottom. Vertical displacement spectra agreed well with GM spectra when solitons were not present. However, when the solitons were present the displacement spectra had higher energy levels compared to the GM spectra. Another experiment was done in October 2004, mainly aimed at characterizing internal solitons and to verify the consistency of the results obtained during October 2002 experiment. This experiment also showed that IWs of both high and low frequency along with internal solitons were present at the experimental site. It was found that internal solitons were more energetic during spring tide than the neap. The observed amplitudes of these solitons were around 12m and were not rank ordered suggesting that the experimental site is close to the generation point. It is believed that, generally, solitons get phase locked to the barotropic tide’s trough and travel. Such phase locking was not observed at the experimental site. They were observed riding on both troughs and crests of barotropic tide. One of the aims of this thesis is to develop a simulation model based on Garrett-Munk steady state internal wave spectrum. Hence, an internal wave model IWAVE was developed to simulate the sound speed structure due to internal waves. Sound speed structure is simulated instead of TS structure, because of their direct utility in sonar range prediction models. Since the GM model is a deep-water and mid-latitude model, it was calibrated to suite shallow-water tropical environment by incorporating the site and region specific parameters. EOFs and Dynamical modes estimated using TS profiles were used to identify the site-specific parameters of the GM model. Values for characteristic mode number and spectral slope used in the GM model are 3 and 2 respectively. However, it was found that they are different in the northeastern Arabian Sea. At this site, the characteristic mode number was found to be 1 and the spectral slope was found to be 3. The modified model was validated against the measured sound speed profiles. In the first case, the first sound speed profile (TS) of the CTD yo-yo data (20 October 2002) was used for predicting the remaining profiles and compared them with observations. This was done to verify the model’s ability to predict high frequency case (TS profiles are measured at every 2.5min.). In the second case, during October 2004, TS profiles collected at every one-hour for 24 hours were used. This gives an idea of the model’s performance for the low frequency case. The variances of the measured and simulated sound speed profiles matched well in both cases with the modified GM model.

The dynamic wave model (the complete form of the saint-Venant equations), as applied to flow routing in irrigation canals or flood routing in natural channels, is associated with parameter and model uncertainties. The parameter uncertainty arises due to imprecision in the estimation of Manning’s n used for calculating the friction slope (sf) in the momentum equation of the dynamic wave model. Accurate estimation of n is difficult due to its dependence on several channel and flow characteristics. The model uncertainty of the dynamic wave model arises due to difficulty in applying the momentum equation to curved channels, as it is a vector equation. The one-dimensional form of the momentum equation is derived assuming that the longitudinal axis of the channel is a straight line, so that the net force vector is equal to the algebraic sum of the forces involved. Curved channel reaches have to be discretized into small straight sub-reaches while applying the momentum equation. Otherwise, two- or three-dimensional forms of the momentum equation need to be adopted. A main objective of the study presented in the thesis is to develop a fuzzy dynamic wave model (FDWM), which is capable of overcoming the parameter and model uncertainties of the dynamic wave model mentioned above, specifically for problems of flow routing in irrigation canals and flood routing in natural channels. It has been demonstrated earlier in literature that the problem of parameter uncertainty in infiltration models can be addressed by replacing the momentum equation by a fuzzy rule based model while retaining the continuity equation in its complete form. The FDWM is developed by adopting the same methodology: i.e. By replacing the momentum equation of the dynamic wave model by a fuzzy rule based model while retaining the continuity equation in its complete form. The fuzzy rule based model is developed based on fuzzification of a new equation for wave velocity, to account for the model uncertainty and backwater effects. A fuzzy dynamic wave routing model (FDWRM) is developed based on application of the FDWM to flow routing in irrigation canals. The fuzzy rule based model is developed based on the observation that inertia dominated gravity wave predominates in irrigation canal flows. Development of the FDWRM and the method of computation are explained. The FDWRM is tested by applying it to cases of hypothetical flow routing in a wide rectangular channel and also to a real case of flow routing in a field canal. For the cases of hypothetical flow routing in the wide rectangular channel, the FDWRM results match well with those of an implicit numerical model (INM), which solves the dynamic wave model; but the accuracy of the results reduces with increase in backwater effects. For the case of flow routing in the field canal, the FDWRM outputs match well with measured data and also are much better than those of the INM. A fuzzy dynamic flood routing model (FDFRM) is developed based on application of the FDWM to flood routing in natural channels. The fuzzy rule based model is developed based on the observation that monoclinal waves prevail during floods in natural channels. The natural channel reach is discredited into a number of approximately uniform sub-reaches and the fuzzy rule based model for each sub-reach is obtained using the discharge (q)–area (a) relationship at its mean section, based on the kleitz-seddon principle. Development of the FDFRM and the method of computation are explained. The FDFRM is tested by applying it to cases of flood routing in fictitious channels and to flood routing in a natural channel, which is described in the HEC-RAS (hydrologic engineering center – river analysis system) application guide. For the cases of flood routing in the fictitious channels, the FDFRM outputs match well with the INM results. For the case of flood routing in the natural channel, optimized fuzzy rule based models are derived using a neuro-fuzzy algorithm, to take the heterogeneity of the channel sub-reaches into account. The resulting FDFRM outputs are found to be comparable to the HEC-RAS outputs. Also, in literature, the dynamic wave model has been applied in the inverse direction for the development of centralized control algorithms for irrigation canals. In the present study, a centralized control algorithm based on inversion of the fuzzy dynamic wave model (FDWM) is developed to overcome the drawbacks of the existing centralized control algorithms. A fuzzy logic based dynamic wave model inversion algorithm (FDWMIA) is developed for this purpose, based on the inversion of the FDWM. The FDWMIA is tested by applying it to two canal control problems reported in literature: the first problem deals with water level control in a fictitious canal with a single pool and the second, with water level control in a real canal with a series of pools (ASCE Test Canal 2). In both cases, the FDWMIA results are comparable to those of the existing centralized control algorithms.