圖書典藏及影音數位平台

水庫安全評估技術規範自民國97年公佈試行後，迄今已執行約5年時間，原規範擬定時，即預定辦理檢討工作，俾使未來規範執行時可更符合實際需求。

There are 94 posted reservoirs in Taiwan. It is important to maintain the existing reservoirs because of the difficulty of developing new reservoir. Reservoirs safety evaluation is one of the key practices to maintain the existing reservoirs. Reservoirs safety evaluation is following the regulation of "Approach for Hydraulic Structures Inspection and Safety Evaluation (2003)" and "Technical Guidelines for Hydraulic Structures Inspection and Safety Evaluation─Reservoir Construction and Water-Conveying Construction (2008)", and it has been practiced many years and accumulated much experience in Taiwan. Recently, several dam break accidents worldwide and Unite States of America, Canada, and mainland China have initiated reviewing the reservoirs safety evaluation regulation in order to lower the risk of dam break since the "standard-based" dam safety maintenance is not sufficient. In order to improve the reservoir safety evaluation regulation to be more complete and practical for future operation, this project reviewed the recent regulation and adapted the experience of reservoir operation in Taiwan and other countries. This project is scheduled to be completed in two years. The key items for the first year are followed:  Data collection and interview  Reviewing and correcting reservoirs construction safety operation procedure  Reviewing and correcting safety evaluation standard of hydraulic construction  Training Collected data and interview comments have been used for the reference of this study. This study has gotten 7 conclusions: 1. Standard related to “public safety” Safety evaluation procedures item #2 mentioned “related to public safety” should be applied to all reservoirs include the ones are not constructed or posted by authority. 2. Target of the safety evaluation procedures Safety evaluation procedures item #15 mentioned “conduct structures reach certain scale” should includes reservoir with smaller size but higher potential hazard ones. 3. Reservoir classification Reservoir classification should cover all kind of reservoir. Recommend to add one more classification for the smaller water construction such as ponds. In the same time, because the classification adapted by most countries is based on the potential hazard, and the scale of the reservoir has related consequence, it is recommended to classify reservoir by “type” and “dam break potential hazard”. 4. Evaluation frequency The evaluation frequency is recommended as once in 5 year, same as the recent requirement. It is due to the dense population and the high risk environment in Taiwan. In the case that previous evaluation shown good condition and no alert signal shown after, the reservoir evaluation can be postponed or waived once per authority approval. 5. Feasibility study for safety evaluation by class or by stage Recent hydraulic construction management law classified its target so that the reservoirs safety evaluation should be done by different classes. In the same time, some other countries’ two-stage safety evaluation shows better performance and more practical. It is recommended classifying the recent reservoirs to be 3 classes: class 1 and 2 represent dams and about 47% of all reservoirs when class 3 represents low risk potential reservoirs. Class 3 reservoirs can be practiced by staged safety evaluation and class 1 and 2 are still practiced by recent one-stage safety evaluation. 6. Design flood Compared with the standard used in other countries, design flood in recent safety evaluation regulation is still ok. However, the half of PMF might be smaller than the 200 years returned period flood, where PMF stands for probable maxima flood. Because the design flood for class 2 reservoirs should be larger than the 200 years returned period flood, it is necessary to modify recent design flood to be compiled with the proposed 3 classes’ classification procedure. In order to take a proper PMF, it is recommended that the data/relationship of the world's largest flood peak flow record envelope, Taiwan's largest peak flow record envelope, Taiwan's various reservoirs probable maximum flood envelope and other relationships, to be included in the technical specifications for reference. Per study “Existing Reservoir Safety Risk and Countermeasure of Singular Events under Climate Change”, Dec., 2012, the impaction from climate change is not obvious. It is recommended to hold modification due to climate change for more solid conclusion. 7. Design earthquake It is recommended to modify maximum design earthquake (MDE) per the recommended reservoirs classification. Because the definition of active fall may not be the same, it is recommended to have the technical specifications addendum in the safety evaluation prescribed: "geological data should be on the basis of competent authority". The technical specifications addendum should allow result from new technique such as Logic Tree or Deaggregation. As of the generation of respond spectrum, it is recommended to maintain the recent method, but list the “attenuation formula” as addendum in the safety evaluation.