Taiwan is surrounded by the ocean. Her coastal plains are the centers of urbanization and economic developments, where various activities have taken place frequently in the regions abundant in natural resources. Having been benefited by the martial law reinforced until 1988, the natural ecology, landscapes and historical relics in many coastal areas were preserved without large scale development. After the abolition of the martial law, many sensitive and vulnerable coastal areas have been affected by over exploitation or improper shore protection schemes undertaken by public and private sectors without due consideration of their consequence, thus resulting in large scale nearshore reclamations for industrial zones and seawalls incorporating precast armor units to replace the coastal strips that were once beautiful sandy beaches. The engineering works associated with these developments not only have spoiled the natural coastal landscapes but also have caused severe beach erosion, in addition to the adverse impact on sensitive and fragile ecological systems. Located in the west of Kaohsiung city, Sizihwan is not only the facade of the gateway of Kaohsiung international harbor, but also a major attraction for the people living in Kaohsiung to gain intimacy with the sea. The sandy sea shore at Sizihwan, bounded between the rocky hills and the northern breakwater to the Kaohsiung First Harbor, is the precious property of Kaohsiung City. The length of the sandy beach of Sizihwan, about one kilometer originally, was halved resulting from the reestablishment of the National Sun Yat-sen University soon after 1980 for land reclamation to make space for her College of Marine Sciences. Due to increasing number of visitors in recent time under the policy of tourism promotion, it has become vital to recover Sizihwan beach to its past glory. For this reason, the Kaohsiung City Government has determined to undertake this project with a comprehensive investigation, in the hope of making Sizihwan a model of scenic and ecological restoration in Taiwan. This thesis reports in details the process of how the Kaohsiung City Government in carrying out the Sizihwan restoration project since 2005, It consists the complete events from planning, tendering, extra funding to engineering implementation, to serve as the first technical literature in Taiwan for the construction of an artificial headland-bay beach with nourishment. With the support from people in various government authorities, engineering consultants, construction industries and coastal experts in Taiwan, the promotion of beach recovery at Sizihwan has gained sufficient momentum since 2005, aiming to install two artificial headlands incorporating beach nourishment for the provision of a stable sandy bay beach. The author of this report has had the honor in participating in this unique beach restoration project at Sizihwan, as part of his administration duty while serving himself in the Kaohsiung City Government.

About the software of numerical model, countries to develop model must be base on their main local coast. And the parameters of the software will be built to fit their local coast. But coast are different from every countries. If use the parameters to simulation in Taiwan, the result may be wrong. The study of this paper use SMC(coastal modeling system). To match up different kind of parameters, such as wave¡Bperiod¡Btide to simulate. Search and collect the data on the study of local area over the years. Although first to confer the change of bathymetry on Sizihwan, which influence on the wave of typhoon and monsoon. To understand the bathymetry influence on different type of waves. Then simulate the change of the sea bed by the module of SMC ' Mopla. And compare the result of simulate and the measurement, to probe into the change of bathymetry. The influence of the waves of southwest monsoon on Sizihwan, the characteristic was erosion close-shore and accretion off-shore on the beach. The influence of the waves of northwest monsoon, the characteristic was wave induce the berm. There are best result of simulate the waves of southwest monsoon, but bad at the waves of northwest monsoon.

none

With the changing perceptions in coastal engineering in recent time, creation of bay beach for recreation by combining artificial headlands with nourishment has become one of the favorable options for mitigating erosion and shore protection in several foreign countries advanced in coastal engineering. To achieve this goal, hydraulic model tests and numerical simulations have been applied for the planning and design of stable bay beaches. While using the latter approach, numerical computation includes four major components, these being the waves, topography changes, flow field and sediment transport. This study utilizes the so-called Modified Hsu3D model developed by Serizawa et al. (1996) and Kumada et al. (2002) in Japan for the bathymetry within a static equilibrium bay beach defined by Hsu and Evans (1989). This model enables the direct calculation of bottom bathymetry within a static bay without using not only iterative numerical steps for wave transformation and current distribution, but also the continuity equation for total sediment transport. The results of this simplified approach can be used to estimate the distribution of erosion and accretion within a static bay, hence, suitable for pre-assessment of an artificial beach nourishment project. Prior to applying the Modified Hsu3D model to a bay beach undertaken in this study, sensitivity tests are performed on the setting of several key parameters associated with this model, such as limiting slope on land , limiting slope in the water , height of the berm , alignment angle at downdrift of the bay beach, and wave incident angle . The verification results are then adopted to compare with that reported in Serizawa et al. (2000), as well as to investigate the effects of each parameters on the accuracy of the modeling, in order to enhance the reliability of this model and the setting of the parameters. Finally, the Modified Hsu3D model is applied to simulate the changes in the shoreline and bathymetry for the Sizihwan Bay in Kaohsiung, under the action of normal incident waves during summer monsoon. This study also takes the advantage of the Modified Hsu3D model to explore the effect of oblique wave incidence on the deviation of downdrift control point of a static bay, in order to assist the prediction of downdrift control point for beach changes on an artificially nourished bay beach. The results reveal that the downdrift control point does not shift, under normal incident waves with different for the breaker. On the other hand, under oblique wave action within from the external boundary line of 20 m depth offshore of a bay beach comprising sediment 0.2~0.5 mm, the offset of point (i.e., and coordinates from the original origin) versus wave incident angle can be established. By establishing a regression equation between and versus , the result can be used to assist the determination, more precisely without guess work, on locating the downdrift control point of a bay beach, while working on the MEPBAY (Klein, et al., 2003) on computer screen to assess its stability.