圖書典藏及影音數位平台

新店溪中上游段設有青潭、直潭、屈尺及桂山等堰壩，其操作方式影響上游水位甚鉅，又因新店溪中上游段之治理基本計畫考量維持該河段自然特性，故未計畫施作堤防保護，近年來數場颱洪事件均造成堰壩上游屈尺、廣興地區有淹水情事，因此擬透過本計畫了解青潭堰、直潭堰、粗坑壩及桂山壩平時及颱洪期間操作機制，建立一套河道及堰壩閘門操作之變量流模式，以了解各堰壩在不同操作方式對於重要聚落之洪水位影響，提供相關聚落防洪保護措施及因應策略。

This project hold for 2 years, conducting the analysis of influence of weir and dam operations on flood level of the upper and middle reaches of Xindian River. The result will provide a reference of weir and dam operations, and feasible flood defense strategies to the settlements and river bank areas in the project area. 2014 is the first year of this project, the primary work contents are: 1. Collection and analysis of the basic data 2. Collection of the operation guidance of Qingtan weir, Zhitan weir, Cukeng dam and Guisan dam 3. Simulation of upper and middle reaches runoff 4. Simulation of the unsteady flow induced by weir-dam gate operations The relevant outcomes are summarized as follows: 1. Collection and analysis of the basic data and the weir-dam operation guidance: Hydrological data, past river management and treatment outcomes, historical disaster records, flood protection object survey, current flood protection structures survey, major cross-section and riverbed data and water resource system survey in upper and middle reaches of Xindian River are collected; the operation guidance of Qingtan weir, Zhitan weir, Cukeng dam, Guisan dam and Feitsui reservoir and operation records in past typhoon and torrential events are analyzed. The conclusion can be drawn from the data analysis that the flood storage effect is significant in past typhoon and torrential events and the flexibility of the rule curve in the project area are limited, the lag time of the peak discharge is approximately 1 to 2 hours. 2. Simulation of upper and middle reaches runoff in Xindian River: The runoff simulations ran in this project are using double-layer tank model. The project area is devided to 9 sub-watersheds by considering the locations of the reach joints, weirs, dams and water gauges. The tank model parameters are calibrated using the rainfall and discharge observations in Saora (2014) typhoon event, and then verified by Xangsane (2000), Nari (2001), Krosa (2007) typhoons and the 10-June torrential rain events. The calculation result of the Xindian River runoff model match well to the observation. Be aware that the runoff model and the rainfall frequency analysis result used in this project are different to the previous year, wherefore the runoff result is different to the previous report. 3. Simulation of the unsteady flow induced by weir-dam gate operations: The relevant weir-dam hydraulic routings are using the NewC river model. Simulation module and specific input files are established for Kuisan dam, Ayu Dam and Luohao Dam to compute the water stage-discharge by gate opening degree relation. The dam module of Cukeng dam are established as a broad crested weir, the Qingtan weir and the Zhitan weir module is established as a combination of rating curve and the river model.The simulation result of water level calibrated by Saora typhoon event overlapping with the digital terrain model shows that the indicated overflows are matching recorded inundation areas. The weir-dam modules built in this project are capable of simulating different scenarios associated with given gate operations and rainfall intensities, when the discharge from the upstream exceeds the intake headwater, the stage-discharge relation will be applied.