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Summary of IOT Publications
| Title | The assessments of harbor entrance siltation and adjacent beach erosion induced by the inshore harbor configurations in the eastern coasts of Taiwan. |
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| Dept | Transportation Technology Research Center |
| Year | 2020 |
| Month | 2 |
| Price | 300 |
| Summary | In this study, the inshore harbors indicate that the harbors are located inside the surf zone and could be further implied to the fishery ports of which the depth at entrance is less than -6.0 m. Due to the sediment is highly activated in surf zone, most of the entrance as well as the navigation channel of the inshore harbors have encountered serious silt problems. The purpose of this study therefore focused on investigating the decisive causes associated with proposing the control countermeasures. Applying the Google Earth and reviewing the history images of inshore harbors in Taiwan, we find that the entrance layouts of inshore harbors, which required to defend both of the monsoon and typhoon waves and to ensure superior shelter basins, could be roughly divided into two categories: one is the groins configuration located on the western coast, the other is the detached breakwater configuration located on the eastern coast. With further reviewing the possible impact factors from marine environments and analyzing the erosion and deposition characteristics presented on the shorelines adjacent to inshore harbors, we conclude that the critical causes related to the entrance silts include: (1) the inconsistent impacts from storm tides and high monsoon waves, (2) the flexible beach slopes and nonstationary wave breaking so as to the breaker types, and (3) the special lee side deposition effects derived from the groin and the detached breakwater configuration. Among the critical causes, the detached breakwater effect is worth special mention. For in the shielding zone behind a detached breakwater a salient and even tombolo could be generated. So when the outer breakwater layout of inshore harbors that were planned or extended to be with the configuration of a detached breakwater, serious silt up at entrance should occur. To reduce and to reconcile the serious silt up status occurred at entrance, the proposed crucial control countermeasures are paying highly attention and keeping serious concern on both of the “groin effects” and the “detached breakwater effects” during the stages of planning, extending, and even ordinary maintaining. The decisive strategies raised in this study are: (1) investigating the inshore topography in detail and adapting the beach slope effects as well as the breaker types to fully master the various wave breaking impacts, (2) altering straight and right angle configuration of the shoreline-vertical outer breaker and adopting circular layouts to reduce and reconcile the groin effects, (3) limiting the length of the shoreline-paralleling outer breaker to confine and diminish the detach breakwater effects, (4) executing the reduction engineering to the outer breakers which has been over extended to be the configuration of detached breakwater. |
| Post date | 2020-04-24 |
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