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以Mann-Kendall及Theil-Sen檢定法評估臺灣地區長期河川流量時空趨勢變化

Mann-Kendall Test and Theil-Sen Estimator for Long-Term Spatial and Temporal Trends of Streamflow in Taiwan

摘要


近年來全球受到氣候變遷影響使得降雨型態發生改變,造成降雨時空分佈不均,且逐漸出現降雨兩極化的現象。臺灣位於亞熱帶氣候區,屬乾濕季分明之地區,因此降雨兩極化的現象更加的明顯,而河川流量受到降雨量影響甚巨,使得河川流量於豐水期及枯水期流量的差異更加的擴大,因此對於流量的趨勢及變異性的探討是極為重要的。由於過去甚少針對臺灣地區河川流量進行趨勢特性分析之研究,因此本研究針對臺灣地區整體之趨勢特性進行評估,本研究挑選出臺灣地區四個水資源分區內,流量記錄時間達30年以上共34個河川流量站,以Mann-Kendall檢定法進行年平均流量的趨勢分析,並以Theil-Sen斜率推估法進行趨勢斜率的評估,推算各個河川流量站長時間之變化量。由臺灣四個分區結果顯示,南部區域並無顯著趨勢結果;北部地區8個流量站中僅蘭陽溪流域的西門橋站及淡水河流域的福山站具有顯著趨勢;中部地區6個流量站中,後龍溪流域的打鹿坑站及大甲溪流域的松茂站皆為顯著上升之趨勢;東部地區11個河川流量站中,知本溪流域的知本(3)站及花蓮溪流域的馬鞍溪站為顯著上升趨勢,而卑南溪流域的延平站為顯著下降趨勢。本研究之評估結果可以提供區域水文研究做為水資源規劃參考。

並列摘要


Climate changes have significantly altered the global precipitation pattern in recent years, resulting in uneven temporal and spatial distributions of precipitation, and even precipitation polarization. Taiwan, located in a subtropical climatic zone, experiences discernible dry and wet seasons, making the polarization of precipitation in the country much more obvious. Since stream flow is strongly influenced by precipitation, such polarization results in great stream flow differences between the wet and dry seasons. Thus, it is essential to investigate the trend and variability of stream flow. Little research has been done on trend characteristic analysis of annual average flow in the Taiwan area. This study focused on stream flow data gathered over 30 years at 34 stations located in 4 water resource districts of Taiwan. The Mann-Kendall test was employed in the trend analysis of annual average flow, while the trend slope was assessed using the Theil-Sen estimator, thereby calculating long-term variation in flow at every station. Our observations showed no remarkable flow trend variations in South Taiwan, while only two out of eight flow stations in north Taiwan exhibited significant trend oscillations, namely Ximen Bridge and Fu-Shan stations in Lanyang and Danshui rivers, respectively In central Taiwan, two out of six stations, i.e., Ta-Lu-keng and Sung-Mao stations in Houlong and Dajia rivers, respectively, showed markedly increasing trends. Among 11 flow stations in east Taiwan, Chih-Pen and Ma-An-Chi stations in Zhiben and Hualian rivers, respectively, demonstrated significant flow strengthening, whereas Yen-Ping station in Beinan river reflected the opposite behavior. The results of this study provide references for future water resource planning in hydrology studies at the regional scale.

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