Shoreline response to submerged breakwaters is particularly influenced by the wave field behind the structure driven by coastal processes. The 2D aspects of wave transmission behind submerged breakwaters have been extensively studied by researchers. However, available 2D engineering design tools are inefficient in breakwater design due to not being able to provide any information on the spatial distribution of the nearshore wave field around the breakwater. There are very few studies considering 3D effects in the literature and consequently no reliable guidance for engineers. This encouraged the author to investigate this subject experimentally and numeri¬cally, with the aim of contributing to this important research topic. A comprehensive set of 2D and 3D experiments has been conducted in three wave tanks with different scales. A method has been prepared for predicting the waves transmitted behind the breakwaters based on the data-driven algorithms called Artificial Neural Networks (ANN) and using some of the experimental data collected. Multi-layer perceptron (MLP) and Radial basis function (RBF) models were designed and trained by the Levenberg-Marquardt learning algorithm (LM) and a derivative- based algorithm of gradient descent (GD) respectively. To verify the numerical model, wave simulation was also carried out using DHI MIKE 21 BW (2DH Boussinesq Wave module) based on the numerical solution of the time domain formulations of Boussinesq type equations. The spatial variations of wave energy and wave pattern around the breakwater were generally found to depend on incident wave climate and whether or not wave breaking occurred over the breakwater as well as degree of breaking, with different wave patterns observed for different wave conditions. In cases with waves breaking over the breakwater the lower wave heights were observed behind the breakwater crown on the shorewardside; for nonbreaking wave conditions passing over the submerged breakwater lower wave heights were observed in the gap between the end of the breakwater and the flume wall. Investigations illustrated that the dimensionless Cartesian coordinates x/L₀ and y/L₀ were the most significant parameter in the 3D wave field around the breakwater, with wave height and energy varying spatially around the structure. This confirms the importance of 3D effects on wave height prediction and highlights the inadequacy of 2D models that are unable to deal with spatial variation of wave height behind the breakwater. The RBF model trained by non-dimensional parameters was determined as the most appropriate tool and was proven to be more capable of handling wave transmission prediction comparing with other ANN models. Predictions from the proposed ANN model were found to be in very good agreement with new laboratory data never seen by the model before. The ANN model predictions have also been compared with results from the MIKE 21 BW model. The proposed ANN model was validated in three distinct cases of interpolation, extrapolation and larger scale tests. The model gave the most reliable and convincing predictions within a specific range of input parameters (interpolation) while outside this range (extrapolation) to some extent, reasonable results were still achieved. The proposed model was assessed under larger scale conditions with data collected in another wave tank with different laboratory facilities. Outputs under these conditions also showed good agreement. This shows that the performance of the model is not affected significantly by scale changes and the model has the potential to be used in real applications. The Boussinesq wave model was found to overestimate wave-induced breaking dissipation over the crest of the submerged breakwater leading to underprediction of wave transmission. The evaluations showed more consistency between the measured experimental data and predictions from the ANN model in comparison to those from the Boussinesq wave model. These demonstrate the accuracy and reliability of the model and its capability in predicting the wave field around submerged breakwaters. A simplified version of the numerical model and wave prediction scheme is provided in this thesis for practical applications. The proposed ANN model is a significant advance in that it can be used to predict 3D wave pattern around submerged breakwaters in the range of dimensionless Cartesian coordinate -0.26<x/L₀<O.54 and -O.29<y/L₀<1.7 whereas existing models in the literature are restricted to a 2D field only. The proposed model considers combined transmission and diffraction in a wide range of water depths and wave climates whereas existing models in the literature are restricted to calculating overtopping and diffraction coefficients separately and in a limited range of input parameters which make them less accurate and reliable with lower usefulness and applicability. The agreement with experimental data is encouraging and the evaluations show that the proposed model could be applied in practical applications by engineers and scientists as a more precise and dependable design tool than existing models.

The thesis develops optimisation and modelling techniques with the ultimate aim of control of water distribution systems to produce overall optimised operation. Typical system operating conditions are analysed to determine cost factors and control requirements and hence enable development of system performance criteria. The most significant costs are those for distribution pumping and a range of original optimisation techniques are investigated which will lead to operational improvements for a restricted class of systems. Application of these techntques to more complex systems . is shown to be dependent on development of simplified dynamic models. Suitable models are formulated and computer programs are developed to evaluate matching coefficients for very general systems. Combining the optimisation techniques and s;mrlifie.d models enables a computer algorithm to be devised which can be applied to give optimal control of complex systems taking account of all cost factors and operational constraints. The scheme incorporates a simulation of the overall dynamics of a water system, by means of a tailored computer program, which is initially used with historical operating data for validation purposes. The results confirm the theoretical predictions and show that benefits can be obtained from on-line computer controlled operations.

No description available.

No description available.

Part I deals with the investigation of the Black Esk River water supply scheme using a 1/30 scale model. In the design of hydraulic schemes of this nature, certain aspects of the problem are often not amenable to mathematical analysis and model testing is commonly resorted to. The Black Esk investigation was undertaken to prove the design generally and to provide answers to specific problems. A study of scale effect on bellmouth discharge using the method of dimensional analysis has also been included. PART II describes the experiments on the resistance to flow in open channel bends. These experiments were made to determine the important parameters involved in estimating the energy loss in semicircular bends. It also attempts to find simple equations for computing flow in open channels of non-linear alignment based on certain well established laws. In the laboratory testing of river models, vertical scale and bed slope exaggeration have often been found necessary to offset scale effects. Observations were made on bends, built to different scales, to examine the question of vertical scale and bed slope exaggeration. A dimensional analysis of the problem has made possible a clearer understanding of the experimental findings. Part III concerns the experiments on the action of progressive waves on a bed of sand. It has often been thought that the currents associated with progressive waves, as distinct from tidal currents, may be the cause of large movements of sand. These observations confirm that sand transportation in the direction of wave propagation can occur in considerable amounts. It also revealed that under certain conditions a large inversion of solid discharge in the opposite direction to wave propagation may also be possible.

No description available.

Recent economic conditions and reduced funding, combined with the threat of climate change, mean that more innovative ways of protecting people and property from the impacts of flooding are needed, with current guidance seeking 'portfolios' of responses to flood risk. This thesis explores the evolving flood risk management system and the role of non-structural approaches to reducing risk by developing a conceptual model that incorporates a broad range of structural and non-structural responses, the linkages between them and the way they contribute to managing flood risk. The model enables coherent conversations about components of the flood risk management system with a joint understanding of how different options interact, to allow better decision-making and more effective communication of those decisions and the reasons behind them. Activities with no direct benefit play a vital role in this system by enabling or increasing the effectiveness of other responses. One such activity, the visualisation of flood risk, is explored through the development of a flood incident management visualisation tool. Using the model, high- level methodologies are developed to quantify the benefits of property-level responses (including resistance and resilience measures and the movement of possessions) and of Flood Incident Management enabling asset operation. These generic approaches are applied to specific national and local case studies, which identify scale-appropriate methods for deriving input data. These methods and the wider context that the conceptual model provides provide a useful step towards a consistent approach to quantifying the benefits of non-structural responses in a way that allows future work to build on that foundation.

No description available.

This study examines both the short and long-term impacts a tidal barrage would have on sediment transport, under combined waves and tidal conditions in the Mersey Estuary and Liverpool Bay, and thus the corresponding morphological changes. The TELEMAC model suite is used for the numerical prediction, including the 2D hydrodynamic module (TELEMAC-2D) coupled with the sediment transport model (SISYPHE) and the wave propagation model (TOMA WAC). A new scheme has been developed to simulate the operation of a barrage within the Mersey Estuary, with comprehensive hydrodynamic calibration using the most recent field data. Model results indicate that the construction of a tidal barrage across the Mersey Estuary (under ebb mode energy generation) significantly alters the natural movement of the tide; effectively reducing the tidal range and increasing the low water level upstream of the structure. Due to the strong flows in the vicinity of the barrage, increased erosion is expected in the Narrows. Barrage operation procedures are predicted to alter the siltation rate under the complex spring-neap tidal cycle. Total-load transport residuals for non-cohesive sediments identify that under the present hydrodynamic regime, the Mersey Estuary is a net exporter of sediments, thus resulting in a noticeable increase of the tidal volume capacity in recent years. However, model results have identified that the implementation of a barrage within the estuary would reverse the net sediment pathway, with there being significant accretion upstream of the barrage. Under the new morphodynamic regime created through the implementation of the barrage, it is likely that sediments would continue to accrete within the impoundment area of the scheme for the entirety of its operational lifetime. With the Mersey Estuary potentially becoming a substantial sink for sediment, it would be feasible to assume that the coastline to the north of the estuary would experience a reduction in its source of marine sediment. Various factors influencing the long-term morphological changes in the Mersey Estuary are also reviewed based on the model results presented in this research. Furthermore, the impacts of a tidal barrage on the coastline, and the possible combined influences of sea level rise and the barrage structure are also explored

Looking to a future where the structural stability of single concrete armour layers is based upon numerical investigation, this thesis addresses the first major task, which is the representation of real structures. Coastal structures armoured with concrete units are created in prototype dimensions in a numerical model with satisfied realism for first time. The available 3D computer model based on FEMDEM (the combined finite-discrete element method), which has the capability for multi-body simulation of complex shaped objects, was used. A major challenge was to develop a methodology for the numerical creation of concrete armour layers that would satisfy the stringent criteria required by the designers of breakwater units for on-site constructed 'random' and 'interlocking' systems. A novel feature to obtain realistically tight systems is the use of four initial types of regular orientations of units, which are sequenced appropriately on a pre-defined positioning pattern grid. This new methodology enables different armour layer models to be built, characterised and examined. The scope of the study is limited to dry conditions and performance under oscillatory loading is investigated by means of vibration. Design variables such as initial packing density, underlayer roughness and number of rows are evaluated and the technical criteria are challenged. The use of a different type of unit shape is also examined to show the potential of the developed technology. A set of analysis tools including accurate calculation of packing density on a local and global basis and the distribution of unit displacements after disturbance were developed to evaluate designs. It is confirmed that the packing density is the most important parameter, which influences the performance of armour layers; the tighter the packs, the less are the displacements of units under disturbance. A single armour layer with low number of rows of units also proved to be stable. It is easier for units placed on a relatively smooth underlayer to find tighter positions, causing higher values of total average packing density. But when disturbed, armour layers placed on a rough underlayer are more stable. The use of a different type of unit shape is also examined in this thesis, with the purpose to present the potential of the developed technology to such applications. Results may be considered to have limited applicability to the real behavior of structures under wave action. However, they provide some insights into how such complex coastal structures behave. This research constitutes a stepping stone on the way to models that accommodate wave action and will may one day improve the engineering design and understanding of movement of these concrete armour units.