應用數值模式評估丁壩工於蘭陽溪水鳥保護區魚類棲地改善效益

On Ecological Assessment for the Fish Habitat Improvement with Numerical Models and Consturcted Spur Dikes

施上粟(Shang-Shu Shih) ； 李鴻源(Hong-Yuan Lee) ； 胡通哲(Tong-Jear Hu)

《中國土木水利工程學刊》 20卷3期 (2008/09) Pp. 331-339

https://doi.org/10.6652/JoCICHE.200809_20(3).0005

摘要

本文利用NETSTARS及TABS-2數值模式，模擬蘭陽溪下游段配置丁壩工與否，對魚類可用棲地面積的影響，以量化評估丁壩工的生態效益。定床結果發現：設置丁壩工，有效棲地面積增加幅度約38.4~435.8%，分別發生在Q1.0及Q0.4，顯見高流量時能產生較佳的棲地增大效益。另由動床模擬，發現丁壩後方的緩流區底床有逐漸淤高的趨勢，因而造成棲地面積逐漸減小，模擬結果顯示WUA減少了約7.2%。因此就長期而言，丁壩工掛淤造岸特性反而不利魚類棲息，建議應建立棲地維護機制。本文並根據240組定床及27組動床數值實驗結果，建立短期（定床）及長期（動床）之丁壩工生態效益迴歸公式，可做為工程師實際設計規劃河川復育時之參考，動床迴歸式也可作為丁壩工後方緩流區定期清淤機制建立的參考。

關鍵字

丁壩工 ； 魚類棲地改善 ； 數值模式

並列摘要

A quasi-two-dimensional numerical model, NETSTARS, and a horizontal two-dimensional model, TABS-2, were employed to simulate the hydraulic characteristics, such as water depth, flow velocity and the sediment transport capability of the Lanyang Estuary, in the presence and absence of the constructed spur dikes. These results were used to calculate the weighted usable area (WUA) of Hemimyzon formosanum (Homalopteridae).
The WUA increases 38.4-435.8% after constructing spur dikes. The effects of sediment transport were taken into account as well in the mobile case and compared the results to those obtained from the fixed bed simulation. It is found that WUA of Hemimyzon formosanum (Homalopteridae) decreased 7.2%. Deposition of sediment reduced the habitat area of the fish, which fact is very important to management of their habitat over the long term. Dimensional analysis was also applied and usable regression equations for WUA were obtained from 240 fixed bed cases and 27 mobile-bed cases and can be practiced for engineers for river restorations designation usage.

並列關鍵字

constructed spur dikes ； fish habitat improvement ； numerical model