都市脆弱度的空間分析與能值評估-以台灣西海岸平原洪災為例

Spatial Analysis and Emergy Evaluation of Urban Vulnerability Assessment: A Case Study of Flooding in Taiwan’s Western Coastal Plain

張力方(Li-Fang Chang)

指導教授 ： 黃書禮

國立臺北大學/公共事務學院/都市計劃研究所/博士(2014年)

摘要

全世界超過50%以上的人口聚居在經濟活動與資產高度密集的都市地區。極端氣候事件日益增加所造成的大規模複合型災害，廣泛地影響人類聚居所(human settlement)的安全與財產損失。人類社會在有限的因應能力下，都市地區面對極端氣候事件的發生存在著脆弱性的特性。脆弱度評估為現階段在調適氣候變遷的重要研究議題。在許多氣候變遷對人類的衝擊中，洪災是台灣最立即需要正視的威脅。台灣有超過90%以上的人口聚集在高密度經濟產業軸帶的西海岸平原。由於都市發展的壓力，台灣西海岸平原主要都市與其週邊地區土地使用與地表覆蓋的改變，不僅影響生態系統服務的功能，也同時提高了洪災脆弱度。

脆弱度的觀念是必須考量複合生態與經濟系統間的關係與相互作用，但目前評估都市脆弱度所採用的方法與操作，大多欠缺考量研究地區自然作用、社經條件與都市因應機制系統性的相互作用。因此，本研究的主要目標是建立一個立基在生物物理系統觀，可以整合脆弱度三個組成分 - 暴露(exposure)、敏感度(sensitivity)與調適能力(adaptive capacity) - 間相互作用的評估架構，並對台灣西海岸平原進行都市洪災脆弱度(urban flooding vulnerability)的評估。為了達到這個目標，本研究以能值(emergy)觀念重新詮釋脆弱度的三個組成要素，並用共通性的能值單位來評估各組成要素的強度，再進一步建立都市洪災脆弱度的能值指數評估脆弱度。為了分析台灣西海岸平原各地區的洪災脆弱度差異，本研究利用土壤覆蓋組合法(Soil Cover Complex Method)與地理資訊系統的空間分析功能分析與討論台灣西海岸平原都市洪災脆弱度之空間性。

本研究依據暴露、敏感度與調適能力的能值評估結果進一步建立五個都市洪災脆弱度能值指數：潛在衝擊指數、都市系統的自我組織能力指數、自然與農業系統的自我組織能力指數、防護能力指數與都市洪災脆弱度指數。在指數研究分析成果中，本研究發現台灣西海岸平原中，潛在衝擊高的都市不必然有較高的都市洪災脆弱度，因這些都市有較佳的調適能力得以降低極端氣候事件所造成的脆弱度。然而像桃園、彰化、台中、台南與高雄地區的許多都市，有相對較高的潛在衝擊，卻沒有足夠的調適能力，因此最後的評估成果屬於高都市洪災脆弱度的地區。透過未來都市發展之情境評估，發現不斷成長與建設之都市，倘若調適能力沒有配合改進，則台灣西海岸平原將有更多的都市成為對洪災具有高潛在衝擊之都市。在評估洪災脆弱度的主題下，本研究所提出的能值方法得以有效地整合暴露、敏感度與調適能力的評估。

關鍵字

土壤覆蓋組合法 ； 台灣西海岸平原 ； 能值評估 ； 都市洪災 ； 脆弱度評估

並列摘要

Currently, more than 50% of world population resides in urban areas. The consequences of the increasing extreme climate events are having widespread and significant negative impacts on human settlement. The insufficient ability of human society to cope with climate change has caused the vulnerability of urban areas. Vulnerability assessment is an important research theme under the context of climate change adaption. Among all the other impacts caused by climate change, flooding is considered the most immediate threat to Taiwan. Currently, over 90% of the population of Taiwan is concentrated in western coastal plain. Owning to the stresses of urban development, land use and land cover change in peri-urban areas of the major cities of Taiwan not only affect biophysical processes and ecosystem services, but also result in the increase of flooding vulnerability of cities due to climate change. This research argues that the assessment of vulnerability should consider the interaction between components of the integrated ecological economic system. The methodologies and tools used by most vulnerability assessment researches do not take the interactions among natural process, social financial conditions, and urban response mechanism into account. The primary goal of this research is to develop a framework, which is based on the biophysical system perspective, for assessing the spatial vulnerability of Taiwan’s western coastal plain that incorporates the interaction of the three components of vulnerability- exposure, sensitivity, and adaptive capacity. To achieve this goal, this research interprets urban flooding vulnerability based on emergy concepts, develop emergy indices to assess urban flooding vulnerability, and use Soil Cover Complex Method and GIS to analyze and discuss the spatiality of urban flooding vulnerability. Based on the results of emergy evaluation of the three components of vulnerability, five emergy indices are developed to evaluate urban flooding vulnerability: the self-organization capability of urban system index; self-organization capability of natural and agricultural system index; potential impact index, preventing capability index; and urban flooding vulnerability index. As a result, cities with higher potential impact do not necessarily lead to higher vulnerability of urban flooding because the adaptive capacity also contribute to alleviate the vulnerability of cities to the extreme climate events. Several cities (e.g. Taoyuan, Taichung, Changhua, Tainan, and Kaohsiung) have lower adaptive capacity but with higher potential impact index and result in higher urban flooding vulnerability index. The results of scenario analysis indicate if the land use and land cover continue to convert to urban area without improving adaptive capacity at the same time, the urban flooding vulnerability of these cities will increase significantly. Using the framework developed by this research for assessing urban vulnerability, emergy concept can effectively provide a common measuring unit to evaluate exposure, sensitivity and adaptive capacity for the assessment of urban flooding vulnerability in Taiwan western coastal plain.

並列關鍵字

soil cover complex method ； Taiwan’s western coast plain ； emergy evaluation ； urban flooding ； vulnerability assessment

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