圖書典藏及影音數位平台

頭前溪河口段受到外海波浪、潮汐、匯流段交會之水理輸砂影響，歷年來變遷頗為顯著。水利署水利規劃試驗所、第二河川局等單位自民國94年起，陸續辦理河口段之治理規劃檢討、物模試驗、數模研究及工程執行規劃等計畫，目前河口段相關工程已完工約一年，其中舊港島分流工、苦苓腳凹岸丁壩及河口段疏濬等之效益，值得持續評估探討與研究。此外，為了提升河川生態環境之維護與保育概念，結合水文、地文、人文、生物、空間利用，以頭前溪河口段為例，整合相關水利工程措施，營造浮覆地與生態棲地環境，並結合公眾參與，研擬頭前溪河口段生態水利整體規劃，作為未來國內河口治理規劃之參考。本計畫分兩年執行，藉由動床數模工具、生態與人文調查、公眾參與等，進行頭前溪河口段生態水利整體規劃，除了評估河口段舊港島分流工、相關工程措施之效益外，配合座談、說明會等各類型公眾參與型式，結合生態與人文基本調查資料與相關水利模擬分析，綜合呈現整體規劃意涵與風貌，以供相關治理規劃與決策參考。

Influenced by the flow and sediment transport among wave, tide and river’s discharge, the morphology of Touchien River’s estuary has been migrations dramatically in the past years. Several planning of Touchien River’s estuary had been managed by the Water Resources Planning Institute (WRPI), and the Second River Management Office since 2005, which included the Review Improvement Planning, physics experiments, mathematical tests, and engineering projects. The relative engineering projects of the estuary had been completed about two years; it presented that river bed started filling back, so the benefit of setting Jiugang Island diversion dikes, setting Kulingjiao concave bank dikes, and dredging the estuary prone should be assessed and investigated persistently. In addition, aiming at raising the concept of restoring and conserving ecological environment of rivers, both ecological environment and hydraulic engineering should be integrated into the overall planning of eco-hydraulics engineering of Touchien River’s estuary, which combines hydrology, geography, humanity, biology, and space utilization. This study is carried out in two years; in this (first) year, according to the sediment transport model, ecology investigation, and humanity investigation, after assessing the benefits of Jiugang Island diversion dike and other associated engineering, it would be a reference of overall planning of eco-hydraulic engineering of estuary. This planning included several parts: measuring supplementary cross sections of the riverbed, taking twice ecological census of indicator species, calibrating and verifying sediment transport model, investigating hydraulic and erosion mechanisms of Jiugang Island diversion dike, assessing the effectiveness of associated engineering measurements, doing surveying and holding seminars of residents. According to the treatment benefit assessment of Touchien River’s estuary; after Kulingjiao Dikes completed and experienced Soulik, and Trami Typhoons, it shaped bank revetments between each dike. Bank revetments could prevent the footing erosion and enhance safety of river control. In addition, as a well creature’s habitat, bank revetments have great benefit to ecological restoration. The results of numerical model also indicated that, Jiugang Island diversion dike raise 3% discharge of right channel divided by the island; this could balance both the water level and velocity between left and right channels of Jiugang Island; furthermore, the flow of upstream charged the head of Jiugang Island could be reduced, which could improve the efficiency of flood prevention. Simulations analysis of Jiugang Island stated that, under the situation with Bank protection around the island, Jiugang Island was protected by the bank protection; no flooding occurred under Q10. Besides, like other footpath, bank protection around Jiugang Island have fuction of recreation. Dredging estuary prone could reduce flood level and ensure the banks of not being flooding under the Q10; also, the gravel produced by dredging could be used for filling channel or be bade; economic or river preventative benefits would be obtained through dredging.