潮間帶濕地生態水理模式建置及量化之研究

Ecohydraulics model development and quantification of intertidal wetland

施上粟(Shang-Shu Shih)

指導教授 ： 李鴻源

國立臺灣大學/工學院/土木工程學研究所/博士(2005年)

https://doi.org/10.6342/NTU.2005.01132

摘要

本研究主要目標為進行潮間帶濕地生態水利特性量化探討（以關渡自然保留區為例），並據此建立潮間帶濕地經營管理概念模式（conceptual ecohydraulics model），包含：現場調查資料、歷年航照圖判釋、水理輸砂模式、非線性規劃模式及植群變遷預測模式，以底棲生物量、防洪、濕地陸域化及鳥類棲地多樣性為主要的考量因子，進行包括紅樹林疏伐案例的探討。
本論文共分六章，各章節之內容概要如下所述：
第一章 序論：利用5-W構想圖及濕地操作可行性矩陣表論述本文的研究緣起、目的，並針對與本文相關的水利、生態及生態水利研究進行文獻回顧。
第二章 研究架構及生態水利模式理論基礎：根據序論所提及的研究議題及遭遇困難，設計本文研究架構及流程，並據以提出生態水利模式（ecohydraulics model），以整合水利及生態相關的理論，本章並將模式分成數個模組，一一闡述各模組的理論基礎。
第三章 關渡濕地水利特性：進行相關關渡濕地相關水利特性文獻蒐集及現場調查，資料可作為第五章案例分析時之用，分析內容包括感潮特性、水質狀況、全潮測量及床型變化等，以釐清本區可能與生態衝擊直接相關的水利特性。
第四章 關渡濕地生態特性：進行關渡濕地生態相關文獻蒐及及現場調查，生態研究對象根據第一章5-W研究構想圖所述，包括植物（植群變遷）、底棲無脊椎動物及鳥類，以釐清本區之生態特性及其棲地需求，以釐清不同物種可能需要的相關環境因子（水利特性）。
第五章 關渡濕地案例分析：綜合上述各章節所述之資料蒐集及理論基礎，並具體應用於關渡自然保留區的生態水利分析，主要分析目的在於探討水筆仔紅樹林擴張可能造成的防洪衝擊、濕地陸域化及生態衝擊，利用本文所建立的生態水利模式進行相關植群變遷、生態統計分析、環境因子分析、鳥類棲地類型變遷分析及水利分析等，以綜合評估若進行紅樹林疏伐必須面對的生態、水利問題的得失利弊。
第六章 結論與建議：綜上結果，提出具體結論及後續研究建議。

其中，第五章為利用前述章節進行關渡紅樹林濕地案例分析，依第二章建立之潮間帶生態水利模式進行GIS模組之植群變遷判釋、統計模組之底棲動物變化分析、棲地模組之鳥類棲地變化分析、水利模組之紅樹林擴張及疏伐分析及棲地類型變遷預測分析。
GIS模組利用1986、1997、1998、2001及2002年之航拍像片進行植群變遷分析，發現本區之水筆仔紅樹林由1986年的7.2公頃擴增至2002年的23.8公頃，覆蓋面積增加達231％；泥灘地則由1986年的18.1公頃降低至2002年的1.1公頃，覆蓋面積降低達94％，而關乎濕地生命週期的潮間溝則由1986年的6.9公頃降低至2002年的4.2公頃，覆蓋面積達39％，由此可知本區之棲地類型已由早期的草本植物（蘆葦、茳茳鹹草）及泥灘地類型轉變為今日的木本植物（水筆仔）之紅樹林沼澤地。
統計模組進行底棲無脊椎動物棲地環境因子分析，經由文獻回顧及現場調查資料進行分析，分別獲得貧毛類、多毛類、端腳類及蟹類之無因次迴歸式，採用之環境因子包括溶氧、土壤水鹽度、營養鹽濃度、底質平均粒徑及篩選係數等；並發現本區優勢種為環節動物門貧毛類，其喜好分佈於紅樹林潮間溝之裸灘地（關1測站），多毛類則喜好分佈於紅樹林、蘆葦混生區之裸灘地（關5測站），由此可知各底棲動物之分佈情形與當地之棲地類型有密切關係。
棲地模組進行鳥類喜好棲地類型之景觀變遷分析，結果發現本區Shannon多樣性指數由1986年的0.98降至2002年0.77；Shannon均勻度指數由1986年的0.77降至2002年的0.56；優勢度指標則由1986年的0.41升至2002年的0.62；由此可知，本區之植群覆蓋情形的確有單調化的趨勢（優勢度升高、多樣性降低）；而2001年及2002年之景觀指數值均相當接近，顯示此二年間之景觀類型變化不大；而鷸、鴴科水鳥偏好之棲地類型（泥灘地）則由1986年的18.1公頃降低至2002年的1.1公頃。
水利模組進行關渡濕地紅樹林擴張效應及疏伐影響分析，擴張效應發現：超過5年頻率之洪水事件，在曼寧n值增加（反應紅樹林擴張效應）10％時，右岸即發生溢堤現象；紅樹林疏伐分析則根據2年、5年、10年及20年頻率洪水分析在不同紅樹林疏伐度情況下，其水位下降情形，並計算在200年頻率洪水延時事件中，紅樹林疏伐可能降低之濕地陸域化問題，結果發現：就防洪及濕地陸域化觀點而言，建議紅樹林疏伐度可控制在10∼20％間，且疏伐對象以成林為優先考量，疏伐地點則可優先選擇西側及南側紅樹林。
就前述之底棲動物（水鳥主要食物來源）分佈棲地類型而言，本文建議紅樹林疏伐在初步階段可控制在10％，且疏伐對象應從西側成林開始，但在疏伐之初應進行表土沖刷監測，以防濕地面積降低；而疏伐之後，應設定生態監測計畫，每1年至少監測一次植物相變化、每季進行底棲動物採樣分析，而鳥類觀測則可考慮以繁殖季及非繁殖季為觀察時間考量，如此才能降低對生態的衝擊，並據此評估相關物種之生態復育課題（如底棲無脊椎動物）。

關鍵字

潮間帶濕地 ； 生態水利模式 ； 水筆仔紅樹林 ； 底棲無脊椎動物 ； 地理資訊系統 ； 景觀類型指數 ； 紅樹林疏伐 ； 生態復育

並列摘要

This study is to establish conceptual ecohydraulics model of intertidal wetland and quantify the characteristics of ecology and hydraulics. The Guandu Nature Reserve was taken as an example in this study. Besides, the fictitious case studies were also investigated and discussed which include density of invertebrate benthos, flooding impact, depositions of wetland and landscape index variations of waterbirds.
Six chapters were constructed and introduction of each chapter was described as follows:
Chp1: The 5-W hypothesis plot was represented to construct the main idea of this chapter. The operating matrix of nature, near-nature and manmade habitat was also brought up to concentrate on the topic and objective of this study. Meanwhile, some literature reviews were cited to support the point of issue and distinguish from the complicated problems in wetland.
Chp2: The theories of ecohydraulics model, including several modules, were constructed and discussed in this chapter. The flow chart and process of this study were also elaborated. The case study in chapter 5 could therefore persist as this chapter well-done.
Chp3: The investigations and collections of hydraulic characteristics, i.e. water surface elevation variations, flow velocity variations and water quality variations, were evaluated and discussed in this chapter. The results of this chapter were basis and foundation of case study in chapter 5.
Chp4: The investigations and collections of ecological characteristics, including landscape variations, benthos density variations, waterbird species variations, different flood surface elevation and sediment deposition variations, were calculated and discussed in this chapter. The results of this chapter were basis and foundation of case study in chapter 5.
Chp5: Several case studies were built up in this chapter to quantify some adverse effects after mangrove spread. Meanwhile, ecohydraulics model were calibrated and verified from different modules validation, i.e. hydraulic module, GIS module, multivariate statistical module, habitat module and assessment module. Moreover, mangrove removal effects were also evaluated in this chapter.
Chp6: Conclusions of above 5 chapters and some useful suggestions were also represented in further study.
Among above introductions of each chapter, several aerial photographs of 1986, 1997, 1998, 2001 and 2002 were differentiated and calculated in GIS module. The results reveal that the coverage area of Kandelia candel (L.) Druce mangrove increased from 7.2 hectare in 1986 to 23.8 hectare in 2002; coverage area of mudflat declined from 18.1 hectare in 1986 to 1.1 hectare in 2002 and coverage area of tidal creek declined from 6.9 hectare in 1986 to 4.2 hectare in 2002. It was thus concluded that the marsh habitats, dominated by Cyperus malaccensis Lam. and Phragmites communis (L.) Trin., have changed into a swamp habitat, dominated by Kandelia candel (L.) Druce.
The relationship between dimensionless density of invertebrate benthos (D’) and environmental factors affected the richness of benthos were analyzed and regressed in multivariate statistical module. Additionally, the environmental factors were investigated and found out as dissolved oxygen (DO), soil salinity (S), concentration of organic matter (TO), substrate size (D) and sieve coefficient (SC). The results show that different species of benthos was fond of different habitat types.
According to the habitat module analysis, the Shannon’s diversity index decreased from 0.98 in 1986 to 0.77 in 2002; the Shannon’s evenness index decreased from 0.77 in 1986 to 0.56 in 2002, and the dominant index increased from 0.41 in 1986 to 0.62 in 2002. It was therefore concluded that the landscape type became monotonous year by year. Furthermore, the preference habitat area of Family Charadriidae and Family Scolopacidae which were original dominant species in this wetland declined from 18.1 hectare in 1986 to 1.1 hectare.
Four cases with different removal ratios were investigated in hydraulic module and was found that the water surface elevation decreases as the removal ratio increases. When the removal ratio of Kandelia candel (L.) Druce reaches 20%, the variations of the water surface elevation in the wetland became insignificant. Significant sediment deposition occurs due to the extensive root network of Kandelia candel (L.) Druce. The average deposition is about 33 mm during a 200 years return period flood event. Removal of Kandelia candel (L.) Druce is able to reduce the sediment deposition rate. When the removal ratio reaches 20%, the reduction in sediment deposition is about 5 mm. Considering the factors of flood protection and sediment deposition, the optimal removal ratio is between 10% and 20%. It is also found that mangrove remove will improve the ecological restoration of Uca (Thalassuca) Formosensis Rathbun which is an endemic species of the fiddler crab in Taiwan.

並列關鍵字

Intertidal wetland ； ecohydraulics model ； Kandelia candel (L.) Druce mangrove ； benthos ； Geographic Information System (GIS) ； landscape type index ； mangrove removal ； ecological restoration

參考文獻

胡通哲、葉明峰，2002，基隆河員山子至八堵河段環境基流量之研究，中華水土保持學報 33 (3) ：241-247。

胡通哲、施上粟、李鴻源，2003，近自然工法水理數值分析之研究─以多望溪為例，中華水土保持學報，34（1）：95-100。

施上粟、李鴻源、胡通哲，2004，台中柳川應用生態工法於魚類棲地改善之研究，中華水土保持學報，35（3）：229-239。

Bai, T. J., T. Cottrell, D. Y. Hau and T.Te, R. J. Brozka, 1997. Multi-dimensional sphere model and instantaneous vegetation trend analysis Ecological Modeling 97, pp.75-86.

Baker, M. C. and E. M. Baker, 1973. Niche relationships among six species of shorebirds on their wintering and breeding ranges, Ecological Monographs 43:193-212.