圖書典藏及影音數位平台

高雄海岸北起二仁溪河口與台南市相鄰，南至高屏溪河口與屏東縣為界，早期即有海岸方面之災害發生，但經多年海堤興建及消坡塊拋置保護，並逐年投入相當多經費興建離岸堤加以保護海岸，目前沿岸尚無重大災情傳出，可謂已達成防止海岸災害之階段性任務。由於離岸堤建構後部分海岸段固沙功效顯著，但在波浪與颱風浪連續作用下，部分海岸段呈現掏刷情形，在海岸侵淤不斷的消長變化下，離岸堤的建構工程常因地方民眾之要求而增建，形成離岸堤建構密度與長度缺乏一致性考量之情形，在新舊離岸堤層層疊疊、疏疏密密的情況下，除形成本海岸段特殊的景觀外，更影響各海岸段海岸保護的成效差異。本計畫主要針對高雄海岸監測調查及離岸堤沉陷原因進行分析，以取得對於整體海岸段較為一致性的保護，研究範圍為二仁溪口至典寶溪口與鳳鼻頭至高屏溪口兩段海岸，其研究目的係期望藉由海氣象等相關基本資料蒐集分析、海岸地形水深測量、灘線與底床質粒徑調查分析工作，進行海岸侵淤比較、離岸堤沉陷原因分析、改善方案及效益評估，作為日後海岸防護及環境營造計畫參考之依據。

The major analysis objects of this project were the investigation results of Kaohsiung coast and the causes of detached breakwater sinking. The analysis was performed for establishing more consistent protection along the coast sections under monitoring. The investigation ambits were from the mouth of Erren Stream to the mouth of Dian-Bao Stream, whose coastal length is about 23.5km and from Fongbitou to Kao-Ping Stream, whose coastal length is about 8km; the total coastal length is about 31.5km. For providing reference data to following coastal projects, this project compared coast erosion and deposition, analyzed the causes of detached breakwater sinking and drafted and evaluated plans for rectifying the effects of sinking. In order to collect the required data, this project collected and analyzed marine meterology data, performed coastal monitoring and analyzed the results of shoreline and bed load grain diameter sample survey.In this year, the project collected and organized the past data about tide level, waves, sea current, coastal sediment, hydrology, coastal ecosystems and coastal protection for analysis. For the measurement and examination of bathymetric condition, this project performed control survey on April 8~9, 2015; the bathymetric survey after winter wave effects were performed between May 28 and June 10; the bathymetric survey after summer wave effects were performed from October 6~16; the survey results and past bathymetric data collected were used to analyze coast erosion and deposition. The survey of shoreline and bed load grain samples were performed on March 18~23; the analysis of sediment samples was performed at the same time.For detached breakwater sinking cause analysis, the results of two airborne LiDAR measurements, which respectively performed on May 6 and October 7, 2015, not only provided detached breakwater level data in the investigated ambit but also were used to assess detached breakwater level changes in the investigated ambit between two measurements. For underwater photograph and scanning of the detached breakwater in the investigated ambit, the underwater sites of detached breakwater were surveyed with underwater cameras and side-scan sonar system. Hudson formula, which are usually used in designing dumped rock embankment, were used to find whether the weight of detached breakwater surface and foot-protection was sufficient for protection against wave effects.In order to assess the effect of detached breakwater on deposition, the comparison between current depositions behind the detached breakwater and the evaluation results of theory proposed by Pope& Dean (1986) was performed to examine the difference between current deposition and theory prediction. Besides, the run-up wave level of seawall in the investigated ambit affected by typhoon waves with return period of 50 years was calculated to assess the wave suppression performance of detached breakwater. For proposing new seawall improvement plans, the causes of detached breakwater sinking and data of current depositions behind the detached breakwater and run-up wave level of seawall were summed.