圖書典藏及影音數位平台

為因應北部地區未來水資源利用與調配問題，經濟部水利署(以下簡稱本署)前身經濟部水資源局於民國80～87年間，陸續辦理雙溪水庫初步規劃、可行性規劃及環境影響評估等工作。有鑑於近年來氣候變遷，再加上基隆地區水資源設施不足，使得缺水風險提高，因此於民國100及101年度陸續檢討前期可行性規劃成果，經評估淹沒區及集水區單純(位置詳附圖1)，壩址條件良好，值得積極推動。經檢討當雙溪水庫上場後與貢寮攔河堰聯合運用，將可滿足基隆地區中長程用水需求及備用水量、改善基隆地區公共給水供水水質、提高水庫下游雙溪地區防洪能力、提高台北及基隆地區雙向水源調度及備援能力、配合生態環境與地方特色，促進水庫及地方永續經營發展及增加水力發電綠色能源等功能，本年度將持續進行雙溪水庫可行性規劃工作，提供未來計畫推動政策擬定上之參考。

This report serves as one of the engineering special reports regarding the feasibility planning review (3) of Shuangxi Dam located at Taiwan’s northern district by conducting a planning review on the engineering of dam and subsidiary structure. The main projects include basic data collection, investigation and analysis, water resource usage review, dam and subsidiary engineering planning review, plan evaluation and other tasks. The geological concerns on another special report regarding “geological drilling and rock mechanic test analysis” that is coordinated this year should already been clarified. The original sheared zone is suggested to amend as shattered zone, and to ensure long-term stability of the dam base, the geological weakness zone should be taken care of. As there are already many domestic cases on relevant treatments, we have thus gathered considerable experience on this matter. Therefore, Shuangxi Dam can resume its previous plan and revision on the proposed dam type to construct a concrete arch dam. Under the premise of not affecting the planning functions, safety and sustainability, this plan should be approached in the direction of lowering the costs as much as possible and performing a feasibility planning review based on the previous planning and revision results. After excluding the geological doubt factors, the construction costs on arch dam project are considered to be the lowest as compared to other dam types as its aggregate transportation costs will cause lowest environmental impacts and its beautiful appearance is able to meet with energy saving and carbon reduction trend much better. After re-planning and reviewing the resource application, desilting strategy and engineering layout of Shuangxi Dam, and under the circumstances that more than half of the evaluation index results on dam sustainable management are in favor to excellent, the sustainability score of Shuangxi Dam is ranked “excellent” based on the sustainability classification of the dam. This indicates that the planning of this dam is deemed sustainable. The engineering costs of various projects of Shuangxi Dam (including hydroelectricity engineering) are $11.255 billions. Coupled with an interest of $1.392 billions throughout the construction period, the total construction costs will come to $12.647 billions. The annualized cost is estimated at approximately $632 millions, and the unit cost of raw water is $13.7 per cubic meter. Based on an alternative plan to provide a diversified water source through desalination, it is estimated that the price earning ratio of Shuangxi Dam is 1.44.