臺灣苗栗外海水下聲景量測分析研究

近年全球暖化以及空氣汙染議題日益被重視，臺灣政府以減少碳排放為目標，積極提高再生能源發電比例，其中以離岸風電為當今大力推動政策之一。但伴隨離岸風場的開發，海事工程巨大的水下噪音以及離岸風機的長期運轉噪音等，皆有可能對該海域之水下聲景造成改變，進而影響許多對聲音敏感之物種。對此，本研究使用被動式水下監測（Passive Acoustic Monitoring, PAM）於苗栗外海進行長時間之水下聲景量測，進而探討及分析苗栗外海水下聲景之時空變化。時間變化部分，本研究透過分析2014至2020年夏季（6至8月）之水下音訊，對海洋風場的建置前後的聲壓位準（Sound Pressure Level, SPL）及水下聲景數值模型進行研究，發現海洋風場建置完成後當地水下之聲壓位準確實有比未興建時大，且興建風場前後之水下聲景數值模型其相關性亦相對低落，證實海洋風場的興建確實對苗栗外海之水下聲景造成影響。而在魚叫聲偵測方面於苗栗外海發現兩種魚叫聲，分別為類型一及類型二，2016年後類型二之魚叫聲開始變得較不活躍，且類型一之魚叫聲伴隨風場建置，其魚叫聲之聲能漸漸變小，出沒時間也逐漸縮短。空間變化部分，本研究使用2014及2019年夏季（6至8月）於苗栗外海兩個不同點位之水下音訊，探討同一時間鄰近海域之水下聲景是否會有差異，研究發現同一時間兩點位之聲壓位準及水下聲景數值模型並無太大差異，依此結果日後在水下監測方面便可以單一點位之聲能基線代表整個風場，進而降低水下佈放之成本。

關鍵字

離岸風力發電；水下聲景；魚叫聲偵測

並列摘要

In recent years, global warming and air pollution have been increasingly concerned worldwide, hence, the Taiwan government has pursued and aimed to reduce carbon emission by promoting the development of renewable energy, especially the establishment of offshore wind farms. However, the development of offshore wind farms will result in elevated underwater noise levels due to the construction and the continual operational noise of the wind turbines, which may hinder the well-being of marine mammals. This research utilizes Passive Acoustic Monitoring (PAM) to monitor the long-term underwater noise levels of the Miaoli coastal with regard to the concern of increased underwater noise, furthermore, study the development of the underwater soundscape over time and space. This study analyzes the recorded underwater acoustic data during summer (June to August), from 2014 to 2020. Evaluating the Sound Pressure Level (SPL) and the numerical model of underwater soundscape before and after the construction of the offshore wind farm, it is found that the underwater sound levels after the wind farm construction are higher compared to prior the existence of the offshore wind farm construction. Further, the correlation coefficient of the before-and-after construction is shown relatively low from the numerical model of the underwater soundscape. It is then confirmed that the construction of the offshore wind farm has influenced the underwater soundscape of the Miaoli shore. In terms of fish chorus detection, it is found that there are two different chorusing types (Type 1 and Type 2) off Miaoli coastal, the type 2 fish chorus reduced in intensity gradually after 2016, and the type 1 fish chorus is found weaker in intensity and the duration is shown shortened after the offshore wind farm is constructed. The development is studied by exploring the variance of the PAM data from 2014 and 2019 between two different locations. The result shows that the average underwater sound levels and numerical model from both locations were similar. Thus, it is then verified that the sound level baseline of just a single location would be sufficient to represent the entire wind farm for future underwater monitoring in turn to reduce the cost of underwater deployment.

並列關鍵字

offshore wind farms ； underwater soundscapes ； detection of fish chorus

參考文獻

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國際替代計量

臺灣苗栗外海水下聲景量測分析研究

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