三維模式應用於探討淡水流量對河口鹽分入侵之影響

Investigation the Effects of Freshwater Discharge on Saltwater Intrusion with Three-dimensional Model

陳偉柏(Wei-Bo Chen) ； 柳文成(Wen-Cheng Liu) ； 許銘熙(Ming-Hsi Hsu) ； 郭義雄(Albert Y. Kuo) ； 程大順(Ralph T. Cheng)

《農業工程學報》 52卷1期 (2006/03) Pp. 35-46

https://doi.org/10.29974/JTAE.200603.0004

摘要

河口位於河與海交界之通道，具有複雜的動力特性，鹽分入侵可以導致或多或少的鹽楔並伴隨著密度流。主要影響河口流況的因素有潮汐、隨季節變化的淡水流量與外海鹽水入侵。三維水動力與開分入侵模式計算潮差與鹽度與實測數據進行比較後，顯示模式的精確性。模式經過驗證後應用於探討淡水流量變化對淡水河口之鹽分入侵與環流之影響。結果顯示低流量(Q75)作用下之河口鹽分入侵距離較平均流量為長，此鹽分入侵的位置與觀測結果相近。本研究亦建立不同淡水流量與鹽分入侵的距離之關係。

關鍵字

三維數值模式 ； 河口 ； 鹽分入侵 ； 淡水流量 ； 環流

並列摘要

Estuaries, the confluence zones between river and sea, show a complex dynamic behavior. Saltwater intrusion can lead to a more or less well-defined salt wedge with associated with density current. The main factors that affect the flow conditions in an estuarine system are tides, varying of freshwater discharge with seasonal variation, and intrusion of saltwater from the ocean. The computed tidal ranges and time series salinity using the three-dimensional hydrodynamic and salinity model compare with observed data. The comparison results show that they are in good agreement. The validated model was then adopted to investigate the effects of different freshwater discharges on saltwater intrusion and circulation in the Danshuei River estuarine system. It shows that the distance of saltwater intrusion under low freshwater discharge (Q75 flow) is longer than that under mean freshwater discharge. Observed distances of saltwater intrusion match the simulated results. The relationships between the distance of saltwater intrusion and freshwater discharge were also established through the model prediction.

並列關鍵字

Three-dimensional numerical model ； Estuary ； Saltwater intrusion ； Freshwater discharge ； Circulation