石門水庫集水區強降雨與水體濁度之關聯性研究

Relationship between heavy rainfall and water turbidity in the watershed of Shihmen Reservoir

林雅詩(Ya-Shih Lin)

指導教授 ： 蔡龍珆

國立中央大學/地球科學學院/應用地質研究所/碩士(2012年)

摘要

臺灣水庫集水區山勢陡峭，土石鬆軟，豪雨發生易沖刷地表土石或引發淺層崩塌，臺灣地區主要降雨大致可分為梅雨(3-5月)、颱風(7-9月)、東北季風(11-1月)均替臺灣帶來豐沛的雨量，尤其是颱風季節所夾帶的雨量又急又大，沖刷表土常造成集水區流域懸浮輸砂量激增，進而造成集水區水體的混濁。為瞭解強降雨期間集水區之水文變化趨勢，藉由經濟部水利署北區水資源局自動監測系統以及財團法人農業工程研究中心在颱風期間進行人工監測之水質檢測資料，針對2008至2010年降雨沖蝕地表導致石門水庫集水區之濁度變化進行分析，進而探討強降雨事件與濁度之關聯性，並探討豪雨發生時降雨型態影響河流輸砂量導致水庫水體混濁之差異因素。本研究選定2008年卡玫基、鳳凰、辛樂克、薔蜜颱風和2009年莫拉克颱風及2010年凡那比、梅姬颱風進行探討，結果顯示豪雨期間河流流域中之濁度會受豪雨發生時間、降雨型態及鄰近豪雨次數之影響，就單一事件各測站濁度變化之情形，受到崩塌區域之影響，集水區上游因距離崩塌沉積物來源近，故此區之濁度-流量圖常呈現順時針圈，顯示颱風初期之泥砂供應較颱風後期充足，但也會受颱風事件之不同降雨型態影響，也可能呈現逆時針圈或8字型。而下游測站因距離泥砂供應源遠，理論上泥砂應由上游帶來，於颱風初期上游未攜帶大量泥砂，直至颱風中後期泥砂開始供應，此時之濁度-流量圖應呈現逆時針圈，但受到雨場分布、降雨強度之影響，下游測站有時也會呈現順時針圈或8字型。針對不同雨型颱風事件的討論結果，將有助於未來強降雨導致水庫淤砂的防治工作。

關鍵字

強降雨 ； 懸浮泥砂 ； 濁度

並列摘要

The major portion of sediment yield in Shihmen reservoir was contributed from landslide caused by extreme storm events. Water turbidity of reservoir was often affected due to heavy rainfall that includes plum rain (March to May), typhoon (July to September), and northeast monsoon (November to January) in Taiwan. This study is focused on surface erosion after heavy rainfall in the past three years, so as to assess the relationship between heavy rainfall and water turbidity in the watershed of Shihmen Reservoir. Upper montane catchments of Shihmen Reservoir, from 2008 to 2010 were used to construct hydrological conditions and time series of turbidity. The effects of seven typhoon events namely Kalmaegi, Fung-Wong, Sinlaku, Jangmi, Morakot, Fanapi, and Megi were examined. It was found that the relationship between discharge and turbidity was related to the antecedent rainfall, rainfall characteristics, and the timing of the events in the typhoon season. In contrast, typhoons which took place right after others showed clockwise hysteretic loops in the upstream of catchment area, indicating signs of sediment depletion. Sometime the turbidity- discharge relations exhibit counterclockwise or figure eight attributed to different rainfall characteristics. On the other hand, typhoons showed counterclockwise hysteretic loops in the downstream of fully supplied catchment area, indicating signs of sediment supply. Furthermore, some of the turbidity- discharge relations exhibit clockwise or figure eight can be attributed to different rainfall characteristics. The correlation of hydrological conditions and turbidity is expected to be beneficial in the mitigation of sediment yield of Shihmen Reservoir for future typhoon events.

並列關鍵字

Heavy Rainfall ； Turbidity ； Suspended Sediment

參考文獻

﹝13﹞ 盧惠生，「蓮華池地區降雨－延時－頻率關係及不同降雨延時之設計雨型歷線」，臺灣林業科學，第14卷第1期，63~76頁，1999年。

﹝19﹞ 行政院農業委員會水土保持局，石門水庫及其集水區整治計畫可行性規劃報告，2006年。

﹝20﹞ 梁惠儀、許振崑、林伯勳、鄭錦桐和冀樹勇，「極端暴雨事件於石門水庫集水區之土壤沖蝕量估算及探討」，中興工程季刊．第106期， 5-15頁，2010年1月。

﹝23﹞ 朱怡亭和徐美玲，「玉峰集水區颱風事件河川流量和懸移質濃度關係之研究」，地理學報，第49期，1~22頁，2007年。

﹝37﹞ 許盈松、蔡俊鋒、魏綺瑪與黃宏莆，「水庫泥砂濁度與濃度率定關係研究-以石門水庫為例」，農業工程學報，第53卷第1期，62~71頁，2007年3月。