高空間解析度都市水足跡評估與低衝擊開發設施效益分析

Urban water footprint accounting with GIS-based high spatial resolution and low impact development (LID) performance analysis

莊雯凱(Wen-Kai Chuang)

指導教授 ： 闕蓓德

國立臺灣大學/工學院/環境工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801241

摘要

全球的水資源缺乏(water scarcity)議題正隨著氣候變遷、全球人口數與人口密度的增加，以及更多地區的都市化與工業化而日趨嚴重；而位於人口集中的都市地區，在未來更是水資源缺乏衝擊的首當其衝區域。也因此，都市地區的水資源管理甚為重要，並需要兼顧全面性以及細緻性的水資源評估指標，分析都市地區的水資源消耗情形，進而研擬應對水資源消耗的減量措施。其中，水足跡評估方法目前被廣泛地應用於集水區以及農產品等不同尺度之水資源消耗分析，提供不同水資源消耗者的水資源消耗量資訊；另一方面，低衝擊開發設施(Low impact development, LID)之技術則做為水資源消耗的新興減量策略，以低成本、低環境衝擊以及低耗能的方式攔截雨水資源並加以再利用。然而，目前水足跡分析的空間尺度多為集水區尺度，並較少以都市尺度進行分析，更無分析都市內部空間上的水資源消耗熱點與變異性之相關文獻；此外，目前的LID相關文獻僅針對小規模的實場，分析逕流削減的效益；都市水資源管理者在大規模設置LID時，也需要得知優先設置的地區以及評估設置後的逕流減量效益；目前也沒有以水資源評估指標分析LID在逕流削減過後，能夠為都市水資源消耗帶來的減量效益。
本研究針對臺北市地區建立高空間解析度之水足跡評估指標，以地理資訊系統軟體，根據內政部國土利用分類建立適宜水足跡評估之土地分類系統，藉以區分出都市內部不同的經濟型態，將都市水足跡的總量估算結果進行空間分析，建立以目前空間統計尺度最小的一級經濟發布區之水足跡評估方法，分析小尺度區塊內部的直接用水水足跡(包括藍水足跡、綠水足跡以及都市總體污水產生的灰水足跡)；並根據不同低衝擊開發設施之裝置特性以及合適設置的土地覆蓋種類，整合水足跡消耗熱點之空間分布結果，以地理資訊系統輔助判釋LID的可設置面積，並建立LID的空間設置準則與分析LID的優先設置點位，以大安區為示範區，透過SWMM (Stormwater management model)模式評估雨水回收系統、生物滯留系統，以及透水鋪面於都市降雨逕流的削減量與水足跡熱點的減量效益。
都市水足跡總體的估算結果顯示，三種水足跡的主要貢獻來源為都市人為污水所構成的灰水足跡，以及建築物的藍水足跡；其中又由住宅建築物構成了最大的水資源消耗量；另一方面，藍水降雨逕流量則為次於建築物藍水足跡之水資源消耗，顯示出臺北市地區仍有許多不透水面構成的降雨逕流可被回收與再利用。高空間解析度的建築物藍水足跡分析結果則顯示出，最大的6個水足跡消耗熱點由商業以及機關等用地所貢獻，而住宅建築物則構成了約41個水足跡消耗熱點，從高解析度的分析結果可以顯現不同經濟型態的水資源消耗程度、消耗密度以及都市水資源消耗的空間分布。低衝擊開發設施的減量模擬結果顯示，雨水回收系統具有最多的可設置面積，並能夠達到65%的逕流削減率以及48%的建築物藍水足跡取代率。另一方面，生物滯留系統與透水鋪面的可設置面積則約介於各一級經濟發布區的2%~12%之間，然而相對少量的設置面積之下最多則能夠分別削減32%的都市逕流灰水足跡以及15%的逕流量。藉由本研究所建立的高空間解析度都市水足跡評估、LID空間設置以及減量效益模擬方法，得以顯現都市水資源消耗空間特徵，並依據土地使用特性配置LID裝置，增加都市對於水資源缺乏衝擊的調適能力。

關鍵字

水資源管理 ； 都市水足跡 ； 高空間解析度 ； 低衝擊開發設施

並列摘要

Water scarcity has become one of the major concerned issue throughout the world, which is currently aggravated mainly due to climate change, global population growth, urbanization and industrialization. Among them, urban regions are the most densely populated area, which could be easily affected by water resource depletion impact relative to other regions. Therefore, water resource management can be crucial in solving urban water scarcity issues by identifying spatial hotspots of water consumption and formulating respond strategies in the corresponding hotspots. Urban water footprint (WF) accounting is an emerging method that provides comprehend information of urban water consumption by analyzing blue, green and gray water footprint of different water consumers. Moreover, emerging technology as Low Impact Development (LID) are claimed to be one of the promising technology to recycle and reuse urban rainwater.
However, urban scaled WF accounting couldn’t reveal the spatial variation of water consumption, preventing local water managers from identifying WF hotspots and prior location for water use reduction strategies. In addition, with efficiency and functionality of LIDs remain unknown, there is a need to simulate and assess the practicality of different LIDs implemented with city-wide scale through water consumption indicator. This study aims to establish 1) a bottom-up approached urban WF accounting framework and explore urban WF of Taipei city in 2016 with high spatial resolution characteristic by integrating land use map, spatially detailed water consumption data based on geographical information system (GIS) for the purpose of visualizing spatial pattern of water resource consumption, and therefore 2) establishing spatial installation criteria for LIDs according to spatial hotspots of WF, which are then integrated with 3) SWMM (Stormwater management model) modeling to simulate runoff reduction and WF reduction after implementing LIDs (rainwater harvesting system, bioretention system and permeable pavement) on the corresponding hotspots with Da’an district as a demonstration area.
The WF accounting results shows that 6 blue WF hotspots with the highest blue WF are found across the city contributed by commercial and institution buildings; while household tap water consumption resulted in the most hotspots. Moreover, considerable amount of grey WF of tap water indicates that WF of Taipei city is highly affected by the water quality of wastewater and ambient water quality regulation. Visualization of WF accounting result also reveals that many blue water runoff hotspots of rainwater could be recycled and reused to reduce tap water consumption in a sustainable way; hotspots of grey WF of rainwater also suggest that further treatment should be applied on urban runoff to ease the pollution load in the river. The relationship of spatial pattern of WF and socioeconomic factors is also discussed.
LID simulation result shows that rainwater harvesting system have the most available installation area, leading to substitution rate of blue WF of tap water up to 48%. However, due to limited data availability, the available area for the installation of bioretention system and permeable pavement are 1% to 12% of each hotspot area on average. Despite the low installation area, there are rather high reduction of gray WF of road up to 32% and runoff reduction up to 15%.
This study seeks to present an integrated urban water footprint assessment with an intuitive WF quantification method, and combining it with spatial characteristics to enhance the adaptability of the city faced with the impact of water resource depletion, and integrating LID performance analysis to assist existing resource management policies.

並列關鍵字

Water resource management ； Urban water footprint ； High spatial resolution ； Low impact development

參考文獻

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