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琳恩颱風對台灣北部降雨量分布之影響及基隆河水患防治之研究

A Study on the Precipitation Distribution of Northern Taiwan Effected by Typhoon Lynn and It's Flood Control along Kee-Lung River

摘要


本研究利用逐時降雨量、GMs衛星雲圖和傳統之地面和高空觀測資料,分析1987年10月23~26日台灣北部和東北部之降水分布,並探討導致台灣北部和東北部豪雨之天氣系統。結果顯示,琳恩颱風環流與東北季風匯合所造成的局部輻合,爲導致台灣北部和東北部豪雨之主要因素之一。雲線及對流雲系在降水分布上亦扮演相當重要的角色,因其移入可增強上述地區之降雨程度。然而,伴隨琳恩之850mb東風槽和高對流層(300 mb)颱風環流與太平洋高壓間之分流,則爲導歡此種對流雲形成與加強之可能機制。 結果又顯示,琳恩颱風影響期間,三個準持續性之多雨中心分別在大屯山區(竹子湖),基隆河上游(五堵)和蘭陽平原以西山區(牛鬥)。造成此三個多雨中心之因素,可能因東北風受山脈阻擋而改變風向而與來自北方海面之暖濕氣流匯合而造成局部輻合,以及地形舉升作用所致。10月24日在上述三區之降雨量分別佔各區四日之總降雨量之61.9%,56.2%及79.3%。導致該日最大豪雨量之雲系雲頂溫度在-41~-63℃,爲颱風影響期間發展最高(即雲頂溫度最低)之對流雲。顯見降雨量之多寡與雲系之雲頂溫度成反比。 基隆河源自台北縣平溪鄉薯榔村與石碇鄉交界分水崙地帶,經瑞芳、八堵、南港而入台北盆地,至關渡匯入淡水河出海。由於台北都會區發展迅速,諸多不當的人文活動與設施,如盲目的山坡地開發、土地利用不當,蓄洪平原闢爲耕地、住宅等,使水土保持敗壞,生態環境失去平衡,洪水乃愈演愈烈。 經由完整的雨量資料,所得的合理降水分析,進而由基隆河谷自然環境的特性及人文環境的影響,本研究擬出一套具有應變能力,且具生態風險分散效益的防洪措施,計包括: (1)加強河道的疏浚與拓寬。 (2)水土保持工作的落實。 (3)防洪頻率年之提高。 (4)基隆河上游員山子分洪道之闢建。 (5)截彎取直利弊之再評估。 (6)台北市中山橋之改建等步驟。 希望有助於減輕今後基隆河上游的洪水來源及利於中、下游洪水的宣洩,並提供台北區防洪治水單位之參考。

關鍵字

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並列摘要


This reasearch uses hourly rainfall data, GMS Satellite cloud charts, conventional surface and upper air obsercation data to analyze precipitation distribution Northern and Northeastern Taiwan during 23-26th October, 1987. In the meantime, the cause of N and NE Taiwan heavey rainfall weather system has been discussed. As a result it shows that the partial convergence which had gathered by Typhoon Lynn circulation and NE Monsoon has made one of main factors of heavy rainfall to N and NE Taiwan. Choud line and convective cloud system are also play the important roles for their moving into these areas strengthening precipitation intensity. But by accompaning with Typhoon Lynn's 850 mb easterlies through, 300 mb upper convective layer of typhoon circulation and among the seperated flows of the Pacific high are the most probable opportunities to forming and increasing convective clouds. It also shows the affected areas during the period of Typhoon Lynn. Three penecontinuous rainy centers are the Ta-turn Mountains, upper course of the Keelung River and westward mountains of Lay-yang plain. The elements of these three rainy centers are probably made by NE Monsoon which had jchanged its direction blocking by the mountains to meet with. ocean suface warm wet air from the north then to form partial convergence and by orographic uplifted. The percentages of the daily rainfa11 (24th, Oct.) to four days total amount rainfall in three centers are 61.9%, 56.2% and 79.3%. The temperature of cloud top is -41 to -61 C. The highest development of convective cloud appeared during the period of maximum daily rainfall. It is obviously that relations between the total amount of rainfall and the temperature of cloud top are negative. The Keelung River flows from its origin through Rueih-fong, Ba-du, Nan-kang into Taipei Basin gathers with Tam-shui River then runs into Taiwan Strait. Since in the rapid developing Taipei metropolitan, the living quality and facilities are deteriorated, such as the over-cultivated of hillslopes, misusing of the land, opening flood plain for crops and housing and so on. These really worsen the water and soil conservation, at last it distroyed the balance of ecology system and flood damages become serious in the whole area. Moreover, from the characterization of nature environment and impact of the human environment of Keelun River basin. This study provides a serics of measurement for flood control with ability of effect expediency and ecological risk dispersion efficiency. It includes: 1).To reinforce the works of deepening and widening Keelung River channel. 2).To do better works of water and soil conservation. 3).To raise the level flood control frequency. 4).To build Yuan-shan-tze flood branch channel into sea in upper course of the Keelung River. 5).To reassess advantages and disadvantages of Keelung River meander cut-off project. 6).To uplift and reconstruct the Chung-shan Bridge in Taipei City.

並列關鍵字

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