河川束縮段滯洪區之水理分析

本文主要在發展一河川束縮段滯洪區之水理分析數值模式。台灣中上游河川束縮段，常由於斷面束縮而形成超臨界流，故河川束縮段附近之流況十分複雜，需考慮使用較精密之水理分析方法。目前國內河川束縮段之水理分析，通常以一維定量流模式爲計算之主要工具，但簡易的一維模式常無法反應複雜之水理現象，尤其是河川超臨界流束縮段附近引起斜震波所產生之水面壅高等情況。本文發展一河川束縮段滯洪區二維水理演算模式，並以苗栗縣後龍溪束縮段爲模式之應用對象，探討該河段之水理情況。模擬結果顯示束縮堤距後，使河川水位產生壅高。本文發展之水理模式可計算河川束縮段滯洪區之水理特性。

關鍵字

河川束縮；超臨界流；震波；數值模擬；全變量消去法

並列摘要

The main purpose of this paper is to develop a mathematical model for hydraulics analysis of flood-plain near river contractions. The supercritical flow always takes place at the upstream and midstream of the river in Taiwan due to the river contractions. Because of the complicated phenomena of the river flow, the advanced hydraulics analysis should be taken into consideration. At present, one-dimensional steady flow models are usually employed to calculate the water stage of the supercritical flow in river contractions. However, the simulated results from the simplified models can not response the complicated characteristics of the supercritical flow, such as water stage increasing caused by the contraction of river section or the oblique shock wave. This paper develops a two-dimensional river flow model which has been employed to simulate the flow field of the river contraction in Ho-Long creek. The simulated results show that the river stage increases with decreasing channel width. The mathematical model developed in this study can be used for simulating the flow characters of the river contractions.

並列關鍵字

River contractions ； Supercritical flow ； Shock wave ； Numerical simulation ； Total variation diminishing

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