In this study, a qualitative and comparative investigation on sediment transport equations used in prediction of rserevoir sedimentation is presented. 32 sediment transport equations, which are selected by literature review on sand and gravel size ranges, grouped according to the median particle sizes on which their derivation based. In order to compare these equations computer program DELTA, which is a one dimensional simulation program developed by Graf and Altinakar (1998) for the prediction of delta formation in resrvoirs, is used. Computer simulation is performed within each group of sediment transport equations in order to determine the most suitable equation for corresponding median diameter of sediment particles. 8 of the equations gave simulation results that are in good agreement with average values related to delta deposition extent, height and location in the reservoir. The effects of river slope change and median diameter change on delta deposition also investigated and simulation results are compared with previous model studies.

In the present study, possible scale effects on the formation of air-entraining vortices at horizontal intakes are studied experimentally. Basic dimensionless parameters that govern the onset of vortices at a horizontal intake in a model and a prototype are stated by dimensional analysis. Series of experiments are conducted on four intake pipes of different diameters located in a large reservoir. The relationship of critical submergence ratio with other dimensionless parameters is considered for a given Froude number and it is found out that the critical submergence ratio is affected by model length scale ratio and its natural result of side-wall clearance ratio and Reynolds number differences between model and prototypes. It is observed that, side-wall clearance ratio is not effective on the critical submergence ratio after it exceeds about 6. In addition to this, Reynolds number limit, beyond which viscous forces do not affect the vortex flow, is found out to be increasing with the increase in Froude number. An empirical relationship, which gives the critical submergence ratio as a function of Froude number, side-wall clearance ratio and Reynolds number is obtained by using data collected in the experiments.

In this thesis, a new computer model (tool) for the reliability-based design of rubble-mound coastal defense structures is developed in which design is carried out in a user frienly way giving outputs on time variant reliability for the predetermined lifetimes and damage levels. The model aims to perform the following steps: 1. Determine the sources of uncertainties in design parameters 2. Evaluate the damage risk of coastal structures which are at design stage and are recently constructed. 3. Study the sensitivity of limit state functions to the design parameters. Different from other reliability studies on coastal projects, a new design computer program is developed that can be easily used by everyone working in coastal engineering field.

Many river bridges fail or are seriously damaged due to excessive local scouring around piers and abutments. To protect a bridge from scour-induced failure, it should be designed properly against excessive scouring and its scour criticality should be checked regularly throughout the service life to take prompt action. The Federal Highway Administration of United States (FHWA) developed a program, HYRISK, as a basis for evaluation of existing scour failure risk of a bridge. It provides implementation of a risk-based model, which is used to calculate the annual risk of scour failure of a bridge or series of bridges in monetary values. A case study is carried out for a bridge crossing Fol Creek in Black Sea Region (close to Vakfikebir), for the illustration of this software. Besides, hydraulic analysis and scour depth computations of the bridge are carried out via HEC-RAS program. Also, a study is carried out to recommend scour countermeasures that can be applied to the aforementioned bridge.

Tyrolean type water-intake structures are widely used on mountain rivers to provide water to hydropower stations. The main concern encountered in these kinds of structures is the amount of water diverted from the main channel and sediment carried by this flow. The diverted flow should not be less than the design discharge of the hydropower station and the amount of the sediment entering the hydraulic system should be minimum. In this study a physical model of a Tyrolean weir was constructed at the Hydromechanics Laboratory and by varying the dimensions of the various components of this system / the length, the inclination angle of the rack and the distance between the rack bars, the amount of water and sediment entering the system were measured for a wide range of discharges. The experiments were conducted in two stages. In the first stage the tests were made with only water, and in the second stage, water and sediment having different gradation were used. Applying dimensional analysis to the related parameters of the system dimensionless terms were defined for water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel flow.

Demand for energy is constantly growing both in the world and in Turkey. Sustainable development being an important concept, development of small hydro power projects has been popular in recent years. Eastern Black Sea Basin in Turkey has a lot of small hydro power potential because of high amount of precipitation and existence of steep slopes. Since the amount of river runoff is the only parameter that is variable in order to determine the power potential, it is vital to estimate the project discharge in ungauged basins accurately that have hydro power potential. Projects discharges of hydro-power plants in ungauged basins have been calculated using conventional methods up to now. This study aims to introduce a statistical model in linear and multi-variate form using the topographical and morphological parameters derived from GIS and hydro-meteorological variables to estimate the specific flow duration curves of potential small hydro-power locations for the selected study areas in Eastern Black Sea Region namely Solakli and Karadere basins. As well as developing an annual regression model using the annual values of hydro-meteorological parameters / seasonal regression model (spring season) has also been developed by including the mean seasonal (spring) air temperature variable instead of snow covered area (SCA) in addition to basin parameters. By studying the spring model, effect of different variables from the annual model were tested and discussed with some recommendations for the future studies.

Wider awareness, proper preparedness and effective mitigation strategies need better understanding of tsunamis and tsunami hazard assessment. Tsunami assessment study covers the exchange and enhancement of available earthquake and tsunami data, development of bathymetric and topographic data in sufficient resolution, selection of possible or credible tsunami scenarios, selection and application of the valid and verified numerical tools for tsunami generation, propagation, coastal amplification, inundation and visualization. From this point of view, this thesis deals with all these components of tsunami hazards assessment. The database of 38 different seismic sources is generated and applied to Eastern Mediterranean Basin by using numerical code called NAMI DANCE. Furthermore, the simulation results are compared and discussed. In the thesis, the difficulties in defining seismic source parameters, the effect of dip and rake (slip) angle on seismic generated tsunamis are evaluated. Moreover, the performance of the numerical code, the accuracy of results, the efficiency of the numerical methods in the application to Mediterranean Basin Tsunamis and the comparisons of simulations in nested domains for Bodrum, Kas and Iskenderun are given as case studies. According to the study, north-west and south-west of Turkey may have tsunami risk more than other regions. The maximum wave amplitudes, which may be expected to occur near the shore, are found more than 4 m. However, maximum positive wave amplitude observed in history is approximately 8 m. The arrival time of first wave to hit the coasts vary in a range of 15 to 60 minutes depending on the closeness of the location to the sources&rsquo / epicenter.

Tyrolean type water-intake structures are commonly used on mountain rivers to supply water to hydropower stations. The amount of water to be diverted from the main channel is the major concern in these kind of structures and should not be less than the design discharge. In this study a physical model of a Tyrolean type water-intake structure was built at the laboratory and the diverted flow from the main channel through the intake structure having steel racks and perforated plates of different types were measured. The experiments were conducted in two stages. In the first stage the tests were carried out with only steel racks having three different bar openings and slopes, and in the second stage, perforated screens of three different circular openings and screen slopes were used. Applying dimensional analysis to the related parameters of the system the dimensionless terms were defined for the water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel discharge.

This study is an experimental research to formulate the discharge over sharp-crested rectangular weirs. Firstly, a series of measurements on different weir heights were conducted to find the minimum weir height for which channel bed friction has no effect on discharge capacity. After determining the appropriate weir height, weir width was reduced to collect data on discharge-water head over weir relationship for a variety of different weir openings. Then, the data was analyzed through regression analysis along with utilization of global optimization technique to reach the desired formulation for the discharge. By taking advantage of a newly-introduced &ldquo / weir velocity&rdquo / concept, a simple function was eventually detected for the discharge where no discharge coefficient was involved. The behavior of the weir velocity function obtained in the present study illustrates the transition between the fully contracted and partially contracted weirs. In addition, the proposed weir velocity formulation is simple and robust to calculate the discharge for full range of weir widths.

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.