As the debate into a changing global climate continues, it is important that coastal engineers and scientists have the most advanced tools to quantify any resulting variation in the coastal environment. This will aid the creation and implementation of effective shoreline management plans to mitigate these changes. This thesis presents a new combined Statistical-Process based Approach (SPA) for modelling storm driven, cross-shore, beach profile variability at a medium-term (annual to decadal) timescale. The methodology presented involves combining the detailed statistical modelling of offshore storm data and a process based morphodynamic model (XBeach), to assess, and quantify, the medium-term morphodynamic response of cross-shore beach profiles. Up until now the use of process-based models has been curtailed at the storm event timescale. This approach allows inclusion of the post-storm recovery period, in addition to individual event impacts, thus allowing longer-term predictions. The use of a process-based model for simulating, both erosion and recovery, expands on previous work on the subject by allowing for the inclusion of antecedent beach profiles within the modelling framework. The XBeach model and the overall SPA procedure were calibrated and validated using measured wave and beach profile data from Narrabeen Beach, NSW, Australia. XBeach was shown to give a good prediction of the post-storm profile for four varying storm events. In addition, by accounting for the hydrodynamic processes that govern accretion, and calibrating parameters accordingly, XBeach was also shown to provide a good representation of berm accretion during recovery periods. The combination of the erosion and accretion models was shown to produce extremely encouraging results at an annual timescale, by successfully following the trends in beach volume and the position of the 0m and 2m beach contours. The simulation of a longer sequence provided comparable medium-term erosion return levels.

Processes and mechanisms of bank erosion on the non-tidal, navigable River Thames were identified and investigated using site specific monitoring and extensive geomorphic surveys. As a lowland, impounded river the Thames has little potential for bank erosion associated with reach-scale morphological channel adjustments. In fact, erosion is closely related to local conditions at the bank and significant processes and mechanisms include fluvial entrainment, slumping, and weakening and weathering of in situ bank material. Approximately 38.5km of eroding bankline was measured (-10% of the total length). Average rates of bank erosion monitored ranged from 0.05ni/yr to -0.5m/yr. The relative contribution to bank retreat of each process or mechanism depends on local conditions such as the use of the bank, the type of bank material and the bank geometry and the type of vegetation. Analysis of the causes of bank retreat at 147 sites along the River Thames revealed that erosion was generally influenced by a combination of factors. Navigation related activities contribute to the bank erosion at nearly all sites (-90%) but is solely responsible for erosion at only about 12%. Factors related to the use of the bank and adjacent land contribute to erosion along -65% of the total length of eroding bank but are the sole influence at only -5%. Channel planform and geometry contribute to -53% of observed bank erosion, but are the sole influence at less than <1% of the erosion sites. A review of selected of erosion control techniques applied on the River Thames suggested that solutions tend to be over-engineered and that strategies adopted were not necessarily appropriate for the causes and consequences of the bank erosion. Furthermore, whilst mitigation measures are often incorporated into the solutions, environmental enhancements are rarely included. Assessment of the causes and consequences of erosion has led to the development of a bank erosion management strategy for the River Thames based on geomorphological and sustainability principles. The strategy is presented as a transferable tool through which to achieve sustainable river management.

The development of modern sailing boats has been based almost entirely on the cooperative efforts of enthusiastic skippers, designers and sail-makers, with very little contribution from scientists and technologists and using just basic scientific principles. In recent times, urgent and strong requests for improved performance, mostly for racing yachts, have guided the interest and the attention of the scientific community in the optimisation of sail performance and design approach. Sailing performance depends on the sailboat velocity, aerodynamic and hydrodynamic characteristics. This thesis focuses on the importance of the quantitative evaluation of the sail loads and how this contributes to the improvement of the performance of a sailboat through the development of a system for aiding sail design and assisting mast design. The objective of this study is to provide an integrated design system, which supplies analysis method and design features via a user-friendly graphical interface of a single-sail configuration. The major achievement is the development of an integrating numerical method, which evaluates loads and their distribution and the consequent deformed sail-shape. It improves sail performance analyses and design of new sails. Summarising, the major achievements are: • efficacy of accurate performance analysis for each sail, for any given shape over all the possible sailing courses; • critical investigation of the sail behaviour in the above-mentioned cases; improved approach to an integrated sail design; improvements in mast design from the structural and aerodynamic point of view; limited design costs, in terms of time consumed and computational power employed; efficacy of the visualisation of novel designed sail and predicted performance, which reduces the number of possible design flaws. hi conclusion, the integrated sail analysis and design system presented has important margins of improvements and diversification: extensions to non-homogeneous and anisotropic sailcloth, to two-sail configuration, windsurfs and integration of the mast.

In this study underground dams are briefly described and detailed information about the design and construction aspects is provided. Since the material, of which dam wall is composed, is the main variable influencing the groundwater behavior, various types of dam wall are discussed. The use and usefulness of the underground dams as a means of sustainable development, and their performance in the management of groundwater resources are analyzed with the help of two example studies. In the first example a hypothetical idealized aquifer is considered, while in the second one, a real aquifer is selected. For the performance evaluation, and for the analysis of the impact of the underground dams on the groundwater behavior, numerical simulation is opted. For that purpose, a well-known computer code, MODFLOW, A Modular Three-Dimensional Finite Difference Groundwater Flow Model of U.S. Geological Survey, (McDonald and Harbaugh, 1988) is used.

The main goal of the present study is to investigate the energy dissipation through inclined screens. Recent studies have shown that screens arranged vertically may dissipate more energy than a hydraulic jump does below small hydraulic structures. In the present study a series of laboratory experiments were performed in order to determine the effect of inclination of the screen on the energy dissipated by the screen. The porosity of the screen used in the experiments is 40%. Inclination angle, thickness of the screen, location of the screen, upstream flow depth, and the Froude number of the upstream flow are the major parameters for the laboratory experiments. Froude number of the upstream flow covered a range of 5 to 24. A screen was located up to a distance 100 times the undisturbed upstream flow depth from the gate and the thickness of the screen was changed in correlation with the depth of upstream flow. The results of the experiments show that the inclination parameter has an insignificant effect on the energy dissipated by the screen. Namely, inclination of the screen does not contribute much in reducing the energy of the flowing water further, compared to vertically placed screens.

The objective of this study is to determine the effect of different roughness types and arrangements on hydraulic jump characteristics in a rectangular channel. Three different types of roughness were used along experiments. All of them had rectangular prism shapes and that were placed normal to the flow direction. To avoid cavitation, height of roughness elements were arranged according to level of the channel inlet, so that the crests of roughness elements would not be protruding into the flow. The effects of roughness type and arrangement on hydraulic jump properties, i.e. energy dissipation, length of the jump and tail water depth were investigated. These properties were compared with the available data in literature and with the properties of hydraulic jump occurred on smooth bed.

ABSTRACT DESIGN OF WATER DISTRIBUTION SYSTEM BY OPTIMIZATION USING RELIABILITY CONSIDERATIONS Akdogan, Tevfik Department of Civil Engineering Supervisor : Assoc. Prof. Dr. Nuri Merzi April 2005, 91 pages In spite of a wide research, design of water distribution networks are not realized using optimization techniques. One reason for this fact is, design of water distribution networks is evaluated, mostly, as a least-cost optimization problem where pipe diameters being the only decision variables. The other motivation for preferring the traditional modeling practice is that, existing optimization algorithms are not presented to the user as friendly as it should be. In fact, water distribution systems are very complex systems such that it is not easy to obtain least-cost design systems considering other constraints such as reliability, in addition to classical constraints related to hydraulic feasibility, satisfaction of nodal demands and requirement of nodal pressures. This study presents a user-friendly package concerning the design of water distribution networks by optimization using reliability considerations / this works employs the algorithm proposed by Goulter and Coals (1986). At the end, a skeletonized network design is offered / various costs are estimated in regard to the degree of reliability.

ABSTRACT EXPERIMENTAL INVESTIGATION OF ENERGY DISSIPATION THROUGH TRIANGULAR SCREENS G&uuml / ng&ouml / r, Endam M.Sc., Department of Civil Engineering Supervisor: Assoc. Prof. Dr. Zafer BozkuS Co-Supervisor: Prof. Dr. Metin Ger May 2005, 82 pages For the present study, a series of experimental works are executed to dissipate energy through triangular screens. Recent studies have shown that the implementation of the screen for energy dissipation is an effective way to extract out the excessive energy of water downstream of small hydraulic structures located in rivers of relatively negligible sediment content. In the present study, double screen arrangement with a porosity of 40% is used. The inclination angle of the screens is opted as 60 degree. The major parameters for the present study are upstream flow depth, location of the screen together with the supercritical upstream flow Froude number for a range covering from 7.5 to 25.5. The gate opening simulating a hydraulic structure is adjusted with various heights of 1 cm, 1.25 cm, 1.6 cm, 1.7 cm, 2 cm, 2.5 cm, 2.7 cm, 3.2 cm and 3.3 cm during the study. The results of the experiments show that the triangular screen configuration with the same pore geometry has no significant additional contribution on the energy dissipation as compared to vertically placed screens. Keywords: Screen, energy dissipation, triangular configuration, porosity, hydraulic jump, supercritical flow.

Non-Darcian flow in a finite fractured aquifer is studied in this thesis. A stream bounds the aquifer at one side and an impervious stratum at the other. The aquifer consists of fractures capable of transmitting water rapidly and porous blocks which mainly store water. Unsteady flow in the aquifer due to a sudden or a gradual rise in the stream level is analysed by the double-porosity conceptual model. Governing equations for the flow in fractures and blocks are developed using the continuity equation. The fluid velocity in fractures is often too high for the linear Darcian flow so that the governing equation for fracture flow is modified by Forcheimer&rsquo / s equation which incorporates a nonlinear term. Governing equations are coupled by an interaction term that controls the quasi-steady state fracture-block interflow. Governing equations are solved numerically by the Crank-Nicolson implicit scheme. The numerical results are compared to the analytical results for the same problem which assumes Darcian flow both in fractures and blocks. Numerical and analytical solutions give same results when Reynold&rsquo / s number is less than 0.1. The effect of non-linearity on the flow appears when Reynold&rsquo / s number is greater than 0.1. The larger the piezometric head gradient, the higher the flow rate and, thus, higher the non-linearity is. The effect of aquifer parameters on the flow is also investigated. The proposed model and its numerical solution is a unique application of non-linear flow models to the fractured aquifers. It can be used in predicting water levels in fractured aquifers and evaluating time dependent flow rates in the analysis of recession hydrographs.

Siltation is becoming a big problem as the dams get older all over the world. Conservation and sustainable management of existing reservoirs is gaining more importance than constructing new dams. In this study the program RESCON, which is outcome of a World Bank sponsored project, has been used to examine sediment removal strategies (flushing, hydrosuction sediment removal, dredging and trucking) for four dams of Turkey namely &Ccedil / ubuk I Dam, Bayindir Dam, ivriz Dam and Bor&ccedil / ka Dam. Sediment measurements are made by governmental agencies in Turkey. In this study characteristics of these measurements will be presented for the future sediment related studies. Then sediment removal strategies which were used in RESCON will be introduced. Evaluation of RESCON results have been made and compared with previous studies for verification except Bor&ccedil / ka Dam, since it is under construction.