親水性緩坡海堤最佳面坡及休憩功能之研究

Abstract

本研究主要目的為探討緩坡海堤堤面坡度對水理特性及建造成本之影響，藉以建構一完善合理之緩坡海堤最佳面坡模式；並經由問卷調查方式，瞭解一般民眾對海岸休閒遊憩活動的偏好與對海岸景觀設計及休閒設施的需求，融入未來緩坡海堤之設計規劃過程中，以期能創造海堤休閒遊憩之功能。 由研析結果顯示，緩坡海堤在面坡愈緩時，比較過去傳統海堤的興建，具有較優越之水理特性，然而亦須付出更高的建造成本代價。經考慮建造成本經濟性與水理特性之優點下，緩波海堤的最佳面坡為cota=5~6(傾斜角a)間，於該面坡範圍內設計建造海堤，除有較高效率之抑制波浪效果，且可兼具建造成本上的經濟效益。 另由問卷調查結果顯示，國人對海岸地區休閒遊憩活動的認定與喜好，大多是偏向於岸上的定點活動，且以較靜態的活動為主，而國人對海岸景觀設計及休閒設施的需求，大多是配合對海岸休閒遊憩活動的偏好而來，這將有利於海堤設施與休閒遊憩活動的相結合，因為這些休憩活動皆可藉由緩坡海堤上相關設施的提供來達成其親水目的。

A mild slope seawall with optimum geometry and multi-recreational functions was suggested to have economic and efficient face slope in this study. The hydrodynamic properties and construction cost ware examined to choose a suitable face slope. The preferred recreational activities and their corresponding to facilities were selected by using questionnaire investigation. From reviewing the previous literatures about hydrodynamic properties of waves on sloping seawalls, we found that a seawall with milder face slope can reduce more wave reflection coefficient, run-up, and overtopping than a traditional seawall with steep face slope. However, more construction cost will be paid for milder sloping seawalls than traditional seawalls under the consideration of the same construction conditions. The economically accepted face slope of seawalls was suggested to be cota=5~6 (bevel angle a) by balancing the increasing rate of construction cost and the reducing rate of hydrodynamic properties. The questionnaire investigation was carried out in His Chu area to indicate the public recreational activities in the beach and requested facilities for the people in Taiwan. The results show that the people in Taiwan are inclined to leisure activities, such as walking, coastalscape looking, but not to sport activities, like riding marine motors et al.. Therefore, some requested recreational facilities, such as chairs, plateform for sitting and corresponding to recreational activities are proposed on different mildly sloping seawalls. In the near future, mild slope seawalls will be built in Taiwan because of the increasing need of the people. The present results will provide a good ready reference for future constructing mild slope seawalls.