2014-05-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/681148摘要：水庫排洪減淤操作就泥砂連續的觀點而言，有助於河道回復至比較自然的狀態，也有助於防止河口及海岸線退縮的國土保育功能，國外研究亦發現適當排淤會加速河道底質粗化，有助於水棲昆蟲利用及魚類產卵利用；但排淤將增加洪汛時期的水體懸浮固體濃度，對敏感水生物會有一定的影響，長期而言對濕地也有加速陸化的風險，其間利弊與水文、水質、泥砂條件及生物特性、環境特色均有關，需深入探討。故掌握下游河道生態敏感區及指標物種，調查其受排砂的衝擊程度，為釐清排洪減淤對下游河道生態影響之主要關鍵。 本計畫提出淡水河生態敏感區位圖及淡水河指標物種分佈圖。這些生態敏感區不但有生態保育價值，且其棲地品質直接受到泥砂淤積的影響，水庫排砂或防淤工程實施後均可能產生直接衝擊，包括：淡水河挖子尾、關渡、竹圍、社子島等紅樹林濕地（前三者為自然保留區），疏洪道下游五股濕地（與關渡及社子島紅樹林濕地同屬關渡國家重要濕地範疇），華江濕地、新北濕地等雁鴨重要棲地（前者屬臺北市野雁保護區，兩者均屬大漢新店國家重要濕地範疇）。根據棲地適合度HSI分數（Habitat Suitability Index）預案分析結果，石門放淤後的確會加速華江及新北濕地陸化速度，小水鴨喜好的灘塗及潮溝的棲地適合度顯著降低，且因陸化影響，水筆仔紅樹林有向上游擴張的趨勢，下游紅樹林濕地則因陸化加劇，有逐步被陸生植物取代的潛勢，尤須特別注意近幾年於下游濕地大量生長的互花米草擴張問題（Sparitna alternifora Loisel），均有待進一步深入探討，並依本計畫提出的「水庫排砂評估及回饋模式」擬訂具體可行的因應對策。<br> Abstract: The sediment effluent form reservoirs not only can help restore the river to a more natural state, but also helps prevent the estuary and shoreline retreat of land conservation features on a continuous point of view. Previous studies found that the appropriate operation of sediment effluent would speed up coarsening the riverbed substrates and thus benefit aquatic insects and fish spawning habitat. However the reservoir sediment discharged into downstream will also increase the concentration of suspended solids during flood period. The sensitive aquatic organisms will have negative impacts in the long run to have accelerated continental wetlands of risk. Therefore the comprehensive understanding and appropriate investigation of sensitive areas and indicator species that might be influenced by the sediment effluent are critical. This study aims at evaluating the influences of ecological function and response of ecosystem through field survey of algae, fish, invertebrate, insect community and the habitat characteristics of mangrove Kandelia obovata and water bird Anas crecca in the Tanshui River system. The HSI model (Habitat Suitability Index) and neural network system model will also be conducted to assess the operation efficiency of the Shihmen Reservoir. The mitigation strategy for the downstream ecosystem from adapting the Shihmen Reservoir operation scheme will be presented accordingly as well.排砂石門水庫淡水河生態系統生態功能sediment effluentShihmen ReservoirTanshui Riverecosystemecological function