人造感潮濕地水位調控機制探討及對棲地品質之影響

The Mechanism and Effect of Water Level Regulation of Created Tidal Wetland and its Influence on Habitat Quality

黃耀陞(Yao-Sheng Huang) ； 黃國文(Gwo-Wen Hwang)

《農業工程學報》 68卷2期 (2022/06) Pp. 45-58

https://doi.org/10.29974/JTAE.202206_68(2).0004

摘要

受環境意識與法規日漸提升之影響，許多濕地主管機關進行棲地營造工程，期望恢復或強化濕地生態功能，其方法之一即人造感潮水位調整系統（Controlled Reduced Tide system, CRT）之設置，在固有之堤防上埋設涵管，引入濕地外潮汐力，營造感潮濕地內棲地多樣性，惟相關工程成效如何，尚待驗證。慮及相關文獻中幾無建立人造濕地涵管特性與棲地品質之關係，本研究透過建立一維水理模式，以量化方式分析不同涵管開口大小、高程對於濕地內水位變化幅度之影響，再以棲地適合度指標（Habitat Suitability Index, HSI）進一步評估棲地品質。本研究以2020年甫竣工之桃園市許厝港人造感潮濕地區域為例，其連結濕地內外接壤處之涵管目前開口面積為4.05平方公尺、底高程約為0.54公尺，又考量其營造目標物種與臺灣常見候鳥種類，本研究以小水鴨（Common teals, Anas crecca）為目標物種建立浸淹超越機率HSI進行分析。研究成果指出，目前濕地內水位變化幅度不足，平均浸淹超越機率HSI僅為0.12，屬於不良棲地。將涵管開口面積加大至25.13平方公尺而固定底高程時，濕地內外最高水位有最小差異，本研究以「臨界面積」稱之，此時濕地平均HSI提升為0.15；將涵管底高程下降至-0.5公尺而開口面積固定時，濕地內外之最高及最低水位有最小差異，本研究以「臨界底高程」稱之，此時濕地平均HSI可提升為0.31。由上可知，涵管開口面積愈大及底高程愈低，將使濕地內外水位變化趨於一致，對於濕地內水位變化幅度亦有幫助，是以未來相關棲地營造工程應參酌濕地外潮汐特性並決定水位調控系統，就臨界情形加以討論，俾利濕地內更具棲地多樣性。

關鍵字

感潮濕地 ； 水位調控 ； 臨界面積 ； 臨界底高程 ； 水位變化 ； 棲地適合度指標

並列摘要

Affected by the increasing environmental awareness and laws, many wetland authorities have carried out habitat creation projects, hoping to restore or strengthen the ecological functions of wetlands. One of the methods is the Controlled Reduced Tide system (CRT). However, the effectiveness of the related projects remains to be verified. Considering that the relationship between the characteristics of created wetland culverts and habitat quality is rarely established in related literature. This study established a one-dimensional hydraulic model to quantitatively analyze the impact of different culvert opening sizes and elevations on the magnitude of water level changes in wetlands. And then use Habitat Suitability Index (HSI) to evaluate habitat quality. This study takes as an example the created wetland in Xucuogang Important Wetland, Taoyuan City, which was completed in 2020. The current opening area of the culvert connecting the inner and outer of the wetland is 4.05 square meters and the bottom elevation is about 0.54 meters. This study used the common teals (Anas crecca) as the target species to establish the HSI for the exceedance probability of submergence. The research results pointed out that the current water level variations in the wetland are insufficient, unlike the large tidal range outside the wetland, and the average HSI is only 0.12. When the culvert opening area is increased to 25.13 square meters and the bottom elevation is fixed, the variations of water level inside and outside of the wetland have the smallest difference. The culvert opening area is called the ＂critical area＂. At this time, the average HSI of the wetland is increased to 0.15. The bottom elevation of the culvert is increased when it drops to -0.5 meters and the opening area is fixed, there is the smallest difference between the highest and lowest water levels inside and outside the wetland. In this study, it is called ＂critical bottom elevation＂. At this time, the average HSI of the wetland can be increased to 0.31. The results were shown that the larger the opening area of the culvert and the lower the bottom elevation, the water level changes inside and outside the wetland will tend to be consistent, which is also helpful to increase variations for the water level changes in the wetland. Therefore, future related habitat restoration and construction projects should consider the tidal characteristics, and determine the water level regulation system, and discuss the critical situation, so as to benefit more habitat diversity in the wetland.

並列關鍵字

Tidal wetland ； Water level regulation ； Critical area ； Critical elevation ； Water level change ； Habitat suitability index

參考文獻

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