濱水植生緩衝帶設計對營養鹽削減效益之研究

Implementation of Riparian Buffer Zone via the Effectiveness of Nutrient Reduction

王嘉君(Chai-Chun Wang)

指導教授 ： 朱子偉

國立臺北科技大學/工程學院/土木與防災研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00494

摘要

濱水植生緩衝帶(Riparian Buffer zone)，係指位於河溪兩側及湖泊或水庫陸地與水域交接地帶的植生區域。它具有減緩地表逕流、攔阻泥沙、削減營養鹽、維護棲地生態多樣性、及保育河川等功能。國內外的研究已證實緩衝帶可有效地削減非點源汙染，為有效的最佳管理措施(Best Management Practices, BMPs)之一，然而國內目前對於緩衝帶的劃設並沒有統一的標準。緩衝帶的長度、寬度、坡度、植生配置與配置地點的水文特性均會影響其汙染削減效益，再者緩衝帶的設置將會影響現有土地使用的經濟效益，另一方面若設計寬度不足則又無法達到汙染削減要求，因此本研究將應用濱水生態管理模式(Riparian Ecosystem Management Model, REMM)，設計翡翠水庫集水區內的濱水緩衝帶配置，期達到最經濟的汙染削減效果。
研究首先應用.Groundwater loading effects of agricultural management system(GLEAMS)模式模擬集水區內典型茶園耕作所產生之非點源汙染負荷，再以此為REMM模式的污染輸入，執行緩衝帶機制模擬。研究同時以集水區內沿濱水區的三種主要土系建立REMM檢定的模擬背景值，模式參數檢定則參考國內外相關緩衝帶實驗的削減效率做適當的參數調整。經調整後的背景值則依不同的坡度搭配緩衝帶不同的寬度與植生配置，以模擬不同情境下的汙染削減率，並以此為評估準則進行緩衝帶的最適設計。
研究結果顯示隨著坡度的增加，緩衝帶的汙染削減效率會遞減，然而當坡度增加至40%以上時，此遞減現象就開始趨緩。接著研究分別以5%和40%的坡度，探討緩衝帶寬度對削減率的影響。結果發現5%的坡度的大小並未對寬度與削減率的關係有顯著影響。模擬結果均顯示寬度在40公尺以上時，汙染削減率只呈現些許提升，而在寬度40公尺時即可獲至極佳的汙染削減效果；當坡度40%與寬度40公尺時對泥砂削減率可達69%，營養鹽也可獲得40%以上的削減率。最後研究再以翡翠水庫集水區的平均坡度(40%)和40公尺的緩衝帶寬度模擬14種不同的植生搭配方案。經過綜合評比結果顯示一年生草本搭配秋季落葉灌木與針葉喬木，可獲至最佳汙染削減效果。本研究結果可做為在翡翠水庫集水區設置濱水緩衝帶的規劃設計參考。

關鍵字

濱水緩衝帶 ； 濱水生態系統管理模式(REMM) ； 非點源污染 ； 營養鹽 ； 最佳管理措施

並列摘要

A riparian buffer zone is defined as a belt of trees, shrubs, and grasses located adjacent to and “up-slop” from a body of water. Essential to control nonpoint source pollution and create a healthy ecosystem for stream, these strips slow and filter sediments and nutrients out of surface runoff before they reach the water bodies. Moreover, the buffer zones stabilize streambanks and floodplains as well as provide habitat for wildlife and fish. The riparian buffer ecosystem has been recommended as one of the Best Management Practices (BMPs) to mitigate nonpoint source pollution effectively. However, the variations of pollution reduction efficiency depend on hydrologic conditions, soil types, sizes of buffer zones, vegetation characteristics, and biomass harvesting managements. In addition, implementation of buffer zone will sacrifice economic production of original landuse while insufficient area of buffer, on the other hand, could not reduce the pollution effectively. Therefore, this study aims to explore the appropriate design of riparian buffer according to the sufficient efficiency of pollution reduction in Feitsui Reservoir watershed by employing the Riparian Ecosystem Management Model (REMM).
First, the pollutant loadings generated from a typical tea farm operation were simulated by Groundwater Loading Effects of Agricultural Management Systems (GLEAMS) model. These outputs from tea garden then will be used as upland inputs to REMM model for pollution reduction evaluation. Three major soil series will then be applied to establish the background scenarios in REMM. Model calibration was performed on the experimental reduction rates adopted from published literatures. Finally, the calibrated backgrounds were used to assess the pollution reduction rate on varying slope, width, and vegetation combination of buffer. The appropriate buffer design will be ultimately obtained through comparison of reduction rates in accordance with different buffer scenarios.
The simulation results show that the pollution reduction efficiencies decrease with increasing slope. However, the decline of reduction rates significantly becomes tender when slope is over 40%. The slopes of 5% and 40% were then selected to further investigate the slope impact on the reduction efficiency controlled by buffer width. The results reveal that slope of 40% other than 5% has noticeable influence on the reduction rates which were resulting from varied buffer widths. Moreover, simulations also indicate that reduction rate only improve a little bit under the condition of 40 m width and over. In addition, the reduction rate could reach 69% and 40% for sediment and nutrient, respectively, with slope of 40% and buffer width of 40 m. Finally, 14 combinations of native vegetations based on the three zone scheme were evaluated for effectiveness of nutrient removal under the condition of 40% slope and 40 m buffer width. The best vegetation combination was found to be annual herbaceous, autumn leaf drop shrub and coniferous tree. The results of this study could be used as general guidelines for designing references for riparian buffer zone in FeiTsui reservoir watershed.

並列關鍵字

riparian buffer zone ； REMM model ； non-point source pollution ； Nutrient ； BMPs

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