沙丘性海岸環境資源保育與劣化土地復育研究---以宜蘭海岸為例---宜蘭海岸沙丘的劣化、復育與永續經營管理(III)
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2010/08-2011/07
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宜蘭沙丘型海岸段，位於蘭陽平原的頭城到蘇澳之間，因為坡降平緩，沙灘寬廣，再加上冬季盛行的強勁東北季節及蘭陽溪所提供的豐富沙源，因而有大規模的沙丘發育。然而近年來由於蘭陽溪輸沙來源的減少，使得這段沙岸的供沙失衡，多處海灘正逐漸縮小，甚而使許多沙丘在颱風事件中受到波浪的強烈侵蝕，形成沙丘侵蝕崖，崖面也逐年崩滑後退。此外近年來因為人口及經濟的發展，對於土地的需求日殷，許多海岸天然沙丘地也逐步被開發利用，部分沙丘脊被剷平，開闢成公路，而在沙丘脊中間的低窪濕地，也被開闢為魚塭及養鴨場，甚至有工業區的開發，造成整個沙丘環境轉趨劣化，破壞沙丘在海岸防禦中所扮演天然海堤功能，同時也破壞沙丘在生態棲地及地形景觀美學的價值。像這種因為對於海岸動態環境特色無知所造成的不當規劃，可能對脆弱、敏感的海岸沙丘環境造成致命的斲傷。不但生態機能盡失，沙丘自然的作用過程亦被阻斷，致使沙丘地貌逐漸消失，連帶引起周遭的環境災害，危及附近居民生命財產的安全。本研究擬將宜蘭沙丘型海岸各種環境如沙灘、沙丘、防風林、濕地等結合，透過對於環境自然作用及生物多樣性的研究，共同討論海岸資源保育與土地利用永續經營管理的問題。 在第一年的計畫成果中，即根據野外實地調查、監測及透過不同時期的地形圖、航照及衛星影像資料的比對分析，總共歸納宜蘭海岸地區沙丘的十一種破壞型態，並進一步據以討論適當的量化評估指標，例如沙丘崖線的後退量、植生覆蓋減損面積量、沙丘中道路分佈密度等，用以綜合評估整體沙丘環境的劣化狀況，提供相關環境永續經營規劃的重要參考。目前正在執行中的第二年計畫主要目標是宜蘭沙丘承載量及永續指標建構，以預防過度的人為不當開發使用造成無法回復的沙丘破壞。 本子計畫今年所提為延續性計畫原第三年計畫，研究重點是在宜蘭沙丘復育與永續經營策略研擬。在面臨未來環境自然變遷和人類活動侵入的雙重壓力下，本研究希望透過前兩年的環境變遷及生物多樣性調查，生態及遊憩觀光承載量與永續指標的建置，評估宜蘭海岸沙丘劣化狀況，並據以提出沙丘復育及永續經營管理的策略。以提供海岸經營管理者對於未來如何保育沙丘、維護自然環境生態、景觀資源及防治風砂災害等實際經營管理問題，作為決策的準則和依據。
The dune coast of Ilan extends from Touchern to Suao. With the help of abundant sand sources supplied from the Lanyang River and the strong northeastern winds blown onshore during winter, it has several rows of well-developed dunes extending at the landward side of the gentle and wide beaches. These dunes act as a buffer to extreme waves and winds, while providing habitats to plants and animals as well. In addition, the dunes shelter human communities on the land and assist the retention of freshwater tables against saltwater intrusion. The beach/dune complex of Ilan may have, however, been placed at risk of permanent deterioration because of recent developments, both natural and artificial. Many beaches are narrowed; erosion dune scarps are formed; and the recession of dune scarp continued. This may be due to the great reduction of sediment supply from the Lanyang River that resulted from illegal, rampant sand mining during the last two decades. Dunes have been removed artificially for the construction of new roads or industrial parks. Low dune slacks are reclaimed as fish- or duck-breeding ponds. The continuous and increased intensity of human use has resulted in extensive and irreparable damages on the dunes ecologically and morphologically. The fragmented management shared by various state agencies and local governments may also cause the environmental degradation. In order to set up the sustainable management principles, there is an urgent need for better understanding of the physical and ecological processes that are responsible for creating and maintaining coastal sand dunes. This integrated research project, through the establishment of a sustainability index table for the coastal dune system, will discuss and propose the appropriate and sustainable management strategies of maintaining both morphological stability and ecological diversity for the Ilan dune coast. Based on the field surveys and map comparisons in the first-year project, eleven types of dune degradation are identified. The results will be used to develop an index assessment scheme for dune degradation that will help in the third-year project for developing sustainable management strategies.
The dune coast of Ilan extends from Touchern to Suao. With the help of abundant sand sources supplied from the Lanyang River and the strong northeastern winds blown onshore during winter, it has several rows of well-developed dunes extending at the landward side of the gentle and wide beaches. These dunes act as a buffer to extreme waves and winds, while providing habitats to plants and animals as well. In addition, the dunes shelter human communities on the land and assist the retention of freshwater tables against saltwater intrusion. The beach/dune complex of Ilan may have, however, been placed at risk of permanent deterioration because of recent developments, both natural and artificial. Many beaches are narrowed; erosion dune scarps are formed; and the recession of dune scarp continued. This may be due to the great reduction of sediment supply from the Lanyang River that resulted from illegal, rampant sand mining during the last two decades. Dunes have been removed artificially for the construction of new roads or industrial parks. Low dune slacks are reclaimed as fish- or duck-breeding ponds. The continuous and increased intensity of human use has resulted in extensive and irreparable damages on the dunes ecologically and morphologically. The fragmented management shared by various state agencies and local governments may also cause the environmental degradation. In order to set up the sustainable management principles, there is an urgent need for better understanding of the physical and ecological processes that are responsible for creating and maintaining coastal sand dunes. This integrated research project, through the establishment of a sustainability index table for the coastal dune system, will discuss and propose the appropriate and sustainable management strategies of maintaining both morphological stability and ecological diversity for the Ilan dune coast. Based on the field surveys and map comparisons in the first-year project, eleven types of dune degradation are identified. The results will be used to develop an index assessment scheme for dune degradation that will help in the third-year project for developing sustainable management strategies.