翡翠水庫集水區非點源污染削減效率評估與不確定性分析

Efficiency and associate uncertainty evaluation of Best Management Practices for nonpoint source pollution control in FeiTsui reservoir watershed

林育丞(Yu-Cheng Lin)

指導教授 ： 朱子偉

國立臺北科技大學/工程學院/材料及資源工程系研究所/碩士(2012年)

摘要

翡翠水庫供應大台北地區民生用水，供水的質與量和集水區的開發管理均受到相關嚴密控管。根據1998至2009年翡翠水庫監測資料顯示，在這10年間有10個月份的卡爾森指數呈現優養狀態。然而自2006年起，水質已有日漸改善的趨勢，但為了保護水庫水質與降低優養化風險，仍需針對污染源訂定削減方案，以達到永續健康水庫水質之目的。
本研究旨在應用不確定性分析理論以集水區模式SWAT(Soil Water Assessment Tool)模擬翡翠水庫集水區水文與水質傳輸並導入機率風險概念，推估集水區設置BMPs後優養化風險降低程度。研究收集集水區1998年至2009年氣象、地文及水文資料進行模式模擬，以1998至2003年坪林站與翡翠水庫大壩站的流量、泥砂和水質資料作為檢定，再以2004至2009年的資料驗證模式模擬集水區與水庫的結果。模擬結果顯示SWAT模式具有分析不同集水區管理作業下長期之水文暨水質反應變化的能力。
研究模擬五種最佳管理作業（Best Management Practices, BMPs）設置於農業用地的污染削減效率，分別為河岸穩定(Stream bank stabilization)、階段平台（Terrace）、田埂(Field border)、肥料管理(Nutrient Management)和作物殘株管理(Crop residue management)。集水區尺度下BMP模擬結果顯示削減率較好的為河岸穩定、階段平台與10m田埂，它們對總磷削減率分別達到6.04%、6.8%和10.4%。
研究中進一步應用蒙地卡羅結(MCS)合拉丁高階方塊取樣法(LHS)和矩形區塊法(OS)，分析19項輸入參數的不確定性對模擬結果之影響，再經由100次模擬求得集水區營養鹽負荷之機率分布，將總磷濃度機率分布應用於水庫水質優養化風險評估，並以甲類陸域水體為標準推估集水區總磷負荷門檻。
最後評估設置BMPs後，優養化與總磷負荷超門檻風險降低程度。模擬結果顯示五種BMPs(河岸穩定、階段平台、10M田埂、肥料管理和作物殘株管理)組合之複合式BMPs，可將世界經濟發展組織檢定優養風險從15%降低至1%；卡爾森指標優養風險可從15%降至2%；而集水區總磷負荷超門檻之風險則從78%降至43%。本研究以SWAT模式模擬結合不確定性分析所得之營養鹽機率分布以取代傳統定率性模式之單一負荷值，將可提供集水區管理者更充分的資訊做為決策分析參考，以利採取適合的污染削減策略，達到維護翡翠水庫水質之目的。

關鍵字

SWAT模式 ； 優養化 ； 非點源污染 ； 不確定性分析 ； 拉丁高階方塊取樣法 ； 營養鹽

並列摘要

The Feitsui reservoir is supply water for Taipei metropolitan area in Northern Taiwan. Water’s quality and quantity and basin development were managemented of Taipei Feitsul Reservoir Administration and Taipei Water Management Office, WRA. However, The monitoring data of the Feitsul Reservoir in 1998-2009 show the decade had ten month Carlson index showing the state of eutrophication, especially when Taipei-Ilan expressway was built and came to operate. However, since 2006, water quality has been day into the trend of improvement. But to protect water quality and reduce the eutrophication of risk. Still provider to control pollution program.
This study aims to apply uncertainty analysis import the probability of the concept of risk. Evaluate the hydrologic and water quality impacts resulting from mixed land uses and various management scenarios on FeiTsui reservoir and its watershed by employing the SWAT(Soil Water Assessment Tool) model. Twelve-year data (1998~2009) of weather, topography, hydrology, and water quality have been collected for model calibration (1998~2003) and validation (2004~2009). Overall, it is concluded that SWAT’s capacity of modeling hydrologic and water quality impacts from various management makes it a useful tool to evaluate appropriate watershed development and BMP efficiency for effective control of nonpoint source pouuution.
The BMP simulations indicate the best scenario, consisting of stream bank stabilization, Terrace, Filter strips, Nutrient Management, Crop residue management。BMPs were simulated individually watershed level impacts nice were stream bank stabilization, Terrace and Filter strips of 10m.Implementing individual BMPs reduced TP loads were 6.04%, 6.8%, and 10.4%.
. The effects of uncertainty in model input parameters will be evaluated by using constrained Monte Carlo simulations based on Latin hypercube sampling (LHS) scheme and Orthroing Samping. Each probability distributions for model output of interest results from 100 model simulations. The developed probability distributions will certainly provide information with desirable probability for specific model output. Finally, employed to the result of TP concentration probability distribution, to assess the eutrophic level of water quality and calculated based on the water quality standards of Category A water bodies work out the threshold of the catchment area of total phosphorus load. Moreover to evaluation implementation of BMPs.

並列關鍵字

SWAT model ； eutrophication ； nonpoint source pollution ； uncertainty analysis ； Latin hypercube sampling ； nutrient

參考文獻

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