序率水文模擬及二維水理輸砂模式於壩移除後 河川形貌變遷分析應用

The Analysis of Channel Evolution after Dam Removal Combining Two Dimensional Hydraulic Sediment Transport Model and Stochastic Hydrology Simulation

黃麗文(Li-Wen Huang)

指導教授 ： 游景雲

國立臺灣大學/工學院/土木工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.00501

摘要

壩體移除會造成一系列的地形，地貌、泥砂運移、深槽線等變化。在研究上，應用解析方法計算泥砂量，並且提供一個概念性預測地貌變化。現今電腦科技的發達，利用一維水理以及輸砂數值模式模擬拆壩後的反應已經廣泛被接受。但一維模式在模擬當中使用平均的概念以至於無法全面的了解地形的演變。故，本研究採用二維水理輸砂模式(SRH-2D)應用在七家灣溪拆壩案例上。SRH-2D是由美國墾務局開發的二維水理輸砂軟體，數值方法使用平均深度的二維聖凡那方程式，可以計算穩態、非穩態、總輸沙量，以及提供多種輸砂公式。本研究認為壩體移除後，河川地貌影響的主要控制因素為水文條件，因此由Shot noise model建立序率水文合成序列，並結合定率水理輸砂軟體，利用過去實測流量資料找出該區域之的水文特性，基於序率水文條件探討壩體移除後河相改變，以序率的形式描述來自水文不確定性下的河川地貌變化，結果討論短、長時間下平均深度、深槽線、土方量的變化，並且用超越機率表示地形的變化。

關鍵字

拆壩 ； 不確定性分析 ； SRH-2D ； 合成水文序列

並列摘要

Dam removal will result in a series of river terrain changes, migration of sediment and other changes in river morphology. In recent, with the state of the art, utilizing one-dimensional hydraulic and sediment transport model to simulate the response after dam removal is common and widely accepted. However, it is highly limited in the model assumption and capacity and not able to provide a comprehensive analysis of channel evolution. On the other hand, an important factor dominates geomorphology after dam removal is hydrologic condition, most time is the discharge in channel. In hydrology, the uncertainty exists naturally, so cannot ideally be determined. Uncertainty is usually caused from high variance of hydrological phenomena in space, and leads to difference between simulation and real situation.

This study applies stochastic hydrological simulation and 2-dimenisonal hydraulic and sediment transport model to analysis channel morphology after dam removal. This study not only makes effort to evaluate to possibility of application of SRH-2D in dam removal simulations, which is a two-dimensional hydraulic, sediment, temperature, and vegetation model for river systems under development at the Bureau of Reclamation. We also combine with deterministic two-dimension hydraulic, sediment model and stochastic synthetic hydrologic time series. Taking the removal of the Chichiawan NO.1 dam as a case study, this study aims to quantify uncertainty of flow condition and has a stochastic prediction with probability of physical response of channel. This research provided a method to stochastically describe channel evolution after dam removal. This method contributes a better understanding in hydrology uncertainty with quantify and probability. The result analysis are compared with filed data and in express of probability, it can extend to discuss uncertainty in dam removal for better decision making.

並列關鍵字

Dam removal ； Uncertainty ； SRH-2D ； Synthetic hydrologic sequences

參考文獻

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