圖書典藏及影音數位平台

花蓮溪水系位於台灣東部花蓮縣境內，為花蓮縣兩大主要河川之一，發源於中央山脈，主流全長約57.3公里，支流計約180公里，總流域面積達2670平方公里，屬中央管河川，並於78年辦理治理規劃，本水系於民國80公告治理計畫。由於原治理計畫規劃已久遠，原已公告之治理計畫已有不符因應集水區內地形地貌變更及氣候改變之需求之虞，爰此辦理花蓮溪水系治理計畫檢討。 其他重點工作項目尚還包括： 1.荖溪與花蓮溪匯流口左岸河川區域檢討 2.馬鞍溪光復堤防與光復1號堤防開口堤回淹及用地範圍線變更問題檢討。 3.光復溪造林種植區域檢討 4.全水系用地範圍線與河川區域線不符區段及需配合局變部份調查工作。 5.購買最新河川地籍圖相關資料（含重測）。

The Hualien River system hasn’t been reviewed since 1989. In these years, the condition of climatic and physiography already changed, the land-use drastic changed along the river, part of land-use range faced on change by public requested and so on. Whole structures prevent standard of The Hualien River system must be considered in the future. The range of plan includes Hualien River, Mugua River, Lao River, Shoufeng River, Wanli River, Matai’an River, Guangfu River, Mofo River and South Cingshuei River. The area of Hua-lien river basin is 1,507.09 square kilometers, which is one-third of the Hua-lien County area. The length of main stream is 57.28 kilometers, which is originated from Mt. Ba-zih in Da-fu district northwest, and runs into the Pacific Ocean in Gian Country. This project were according to principles of the report in the past, it chose 48 stations to carry on the analysis of the storm frequency. The probability distribution goodness of fit test is judged by chi-square test. Thus, the 1 day maximum storm of the best probability distribution is the Logarithm Pearson Type III. Then, it used the Rational Formula, the triangular unit hydrograph method, the Instantaneous unit hydrograph method, the motion wave-terrain unit hydrograph method, and actual measure data to calculated discharge. It proposes to continue using the original value of planning in 1989, because the flows of this computation are all smaller then it. The project performed one-dimensional hydraulic calculations for the Hualien River system by HEC-RAS. The program was developed by the US Department of Defense. It used the original discharge and the cross sections survey data of Hualien River in 2008 to model the hydraulics of water flow through natural rivers. According to the result of HEC-RAS Simulation, the flood drainage ability of Hualien River System approximately satisfies with 100 years recurrence interval flood stage. To analyses the scouring and silting of riverbed in past 20 years, we can found the bed scoured serious before 2008 because of the sandstone dredged. In recent years, the bed Presents scouring and silting balanced situation. Base on results, the intervals of Hualien River main stream and Wu-Li River outlet, the convergence with Guangfu River and South Cingshuei River, the Mofo stream between Bridge Ma-fou NO.3 to Bridge Mofo NO.4 are flood. Especially, the convergence with Guangfu River and South Cingshuei River is an important line of communications for Da- sing Village. The insufficient channels of Hualien River Mofo River many are grass-grown, but never disasters happened because of no protection targets around there. To get a grip on disasters, it collected present situations for the Hualien River system, also did site survey and questionnaire. By reviewing for the flood-prone areas, it also analyzed for the protection standard of branches, the variation of streams coursed and silted up, divergence and convergence for the upstream of Guangfu River, the site of sediment area and river dredging, connection with main stream and branches, river dredging between the road bridge and rail bridge of Mugua River, the subject of opening dike and drainage behind dike. keyword：The Hualien River system, maps telescoped, hydrologic analysis , hydraulic calculations, the present situations.