圖書典藏及影音數位平台

淡水河系自78年禁止採砂後部分河段已有逐漸回淤之情況，部分河段亦因河道轉彎、支流匯入及灘地陸化等因素改變流路影響河防構造物安全，本計畫透過水理輸砂數值模式進行分析，了解淡水河系各河段之沖淤趨勢析，評估各河段的沖淤潛勢，以瞭解河道長期穩定程度與未來變動趨勢等河川特性，進而提出治理及疏濬對策，以供本局未來河川治理之參考。

Tamsui River System is made by three major tributaries - Xindian River, Dahan River and Keelung River. The Tamsui River basin have the largest hydraulic construction investment and flood control measures as well as the sphere of influence of the area rank first in Taiwan. The related projects have been implemented and the implementation period up to 30 years. Although sand mining at the Tamsui River System was originally an approved operation, sand mining has been banned since 1989 because of safety considerations regarding river embankment protection. Since the prohibited on sand mining until now, the siltation is currently observed in some parts of the river which poses a threat to the stability of the embankment structure such as the river turns, tributaries etc. Therefore, Ministry of Economic Affairs Water Resources Agency, tenth river management office was set up this project, it is desirable to plan a three-year period, through the one-dimensional and two-dimensional numerical model sand transport water management analyzed the river and the part of the river reach is easy to changes scouring and deposition. Further speculation stability and develop the river channel stability program. Finally, selected the soil-sand management measures and river dredging area, explored for the condition and assess the feasibility of dredging. The part of discharge rate and sediment load rate curve, this project is according to 1992 to 2013 hydrological annual report and sand transport measurement data. Regression analysis in each water flow measure station of Tamsui River System and suspended sediment load rate as a curve can show the result. According the regression analysis result, every monitoring station the coefficient of determination are more than 0.8 excepted the Quchi and Xiulang monitoring station. The result is similar to the earlier project analysis. In the part of river sediment load rate, follow-up will be obtained through a hydraulic calculation of hydraulic factor table and coordinate each river reach of riverbed sampling data. In Schoklitsh formula, update the river channel sediment transport capability. According to the “Tamsui River channel stability and Soil-sand management and response the measures to investigate and plan (1/3)” in 2014, had analyzed the location of each river reach siltation and regarding the aggregated related laws to choose the suitability of river dredging, after that proposed the follow up hydraulic sediment transport of two-dimensional river reach analysis of the recommendation. The analysis showed that it is recommended to start from, Dahan River flow junction to Fuchou Bridge, Dahan River Ganyuan Bridge to Sanying Bridge, Keelung River Shetzu Bridge to Zhoumei Bridge, Keelung River Minquan Bridge to Chenggong Bridge, Xindian River Yongfu Bridge to Sioulang Bridge, Xindian River Zhitan Yan to Quchi Yan, Sanxia River Sanxia Bridge to Baan Bridge and Sanxia River Daili Bridge to Wantan Zai etc. eight river reach to do the two-dimensional sediment transport analysis. The simulation is focus on dredged and additional protection to do the evaluation. Priority for Dahan River Ganyuan Bridge to Sanying Bridge, Xindian River Yongfu Bridge to Sioulang Bridge and Sanxia River Sanxia Bridge to Baan Bridge to do the dredging. The Vertical cross-sectional stability analysis show that Jingmei River, Sanxia River and Heng River compare with Tamsui River, Dahan River, Xindian River and Keelung River are more stable. The results showed that each river overall lateral variability remain relatively stable, and more to the upstream riparian relatively stable; as a sectional a comprehensive stability index(Φ) analysis, displayed the Keelung and Xindian River are the most stable and relatively Tamsui River and Dahan River unstable.