圖書典藏及影音數位平台

嘉義海堤因興建年代較為久遠，部分海堤構造物長期經日曬雨淋現已產生老化、劣化等現象，另加上地層下陷及潮汐變化沖刷潛在因素，更加危及海堤之結構安全性，影響當地民眾生命財產安全，故有必要針對海堤構造物進行調查及檢測。鑑此，經濟部水利署第五河川局為詳細瞭解嘉義海堤內、外堤身現況及受損情形，並擬定完整評估修復對策，以利掌握整體海岸防護，俾保障堤內民眾生命財產安全，進而提供未來海岸整建規劃設計與環境營造之參考應用，是故辦理本計畫。本案調查內容以外業目視調查及堤頂高程測量、並搭配透地雷達等非破壞檢測等方式，針對嘉義海堤進行全面性安全檢測。其中完成計畫區海堤目視調查及堤頂高測量約14.9公里，另透地雷達完成施測計13,000公尺，並經交叉比對完成驗證，成果大致吻合。另經本案建立之綜合指標評估系統，進行海堤整體安全性評估，評估結果除東石海堤(新吉段)0K+600~0K+800、東石海堤(塭港段)0K+200~0K+400及0K+800~1K+000列入「注意改善」之範疇，其餘堤段則尚屬「計畫改善」。經本計畫詳細調查分析及評估後如列為「計畫改善」層級以上海堤建請能寬籌經費修復，俾免既有破壞點繼續擴大危及海堤安全。

The seawall structure is easily corroded by soil salination. Also, erosion caused by tide, wave and soil seepage make the bottom of the seawall scoured and having piping effect. Moreover, the seawall is further vacated inside. The safety of seawall structure is endangered especially at Chiayi coastal area because of soil settlement and sea level rise. To obtain the inner structural condition of the seawalls and to ensure life and property safety of the public, it is necessary to conduct surveys and inspections for those seawalls. Therefore, Fifth River Management Office, WRA, MOEA performed site inspections and nondestructive ground penetrating radar (GPR) testing to examine inner structural condition and damages of the seawalls, including internal and external cracks, voids, water containing condition and seepage, etc. Thus, this plan is funded to make improvement methods and strategy for future Seawall maintenance and management. This plan accomplished visual inspections of 8 seawalls at Chiayi coastal area. According to the investigation category and descriptions mentioned in section 3-1-2 conclusion, it was suggested to be repaired in first priority to avoid further failure caused by seepage when it was categorized as noted for improvement. The nondestructive testing results showed Dongshih seawall (Shihgi section) at 0k+600~0k+800, Dongshih seawall (Wengang section) at 0k+400~0k+600 and 1k+200~1k+358.5, White-Lake seawall at K+000~2K+200 had larger voids. Although no immediately danger appeared, those seawalls should be tracked and inspected continuously. They should be included in the repair plan when the budget is allowed.Since the location of the plan had settlement, it had problems of drainage, seawater overflows, seawater intrusion and seawater salinization. Because some seawall sections almost reached critical seawall standard and lacked of sufficient height (Wangliao Seawall at 0K+000~0K+200, Wangliao sea at 3K+750~4K+000, Budai salt field Seawall at 1K+200~1K+400), it was necessary to increase the height of seawalls. It is also suggested to prepare sufficient funds to improve the height of seawalls. The following seawalls within this plan scope were evaluated as “noted for improvement” and should be watched intently: Dongshih seawall (Shihgi section) at 0K+600~0K+800, Dongshih Seawall (Wengang section) at 0K+200~0K+400 and 0K+800~1K+000. Others were planned for improvement as suggested to be inspected periodically and at selected time for their safety to avoid flooding and damage.