圖書典藏及影音數位平台

近年來都市高度發展與氣候變遷導致水文量的變異加重，傳統水道拓寬或加高工程手段已無法因應種種環境變遷的衝擊，致洪災發生頻度更甚以往。經濟部水利署於民國108年2月19日公告「逕流分擔實施範圍與計畫之審定公告及執行辦法」，並再隔年5月21日頒布「逕流分擔技術手冊」。本案鑒於急水溪流域內於98年莫拉克颱風、107年0823豪雨及110年0801豪雨等降雨事件皆有嚴重積淹水情形，經淹水模擬分析且協調各主管機關達成逕流分擔，為此，本局依據水利法第八十三條之二規定及「逕流分擔實施範圍與計畫之審定公告及執行辦法」第四、五條規定，辦理逕流分擔評估作業。在治理工程完工後模型檢核之下，中央管之6條河川於各自保護標準下無溢淹情形；台南市管區域排水經整治改善後也無溢淹情形，以上均不納入目標河段。依據 SOBEK 模式歷史降雨事件及定量降雨事件情境模擬成果、歷年颱風淹水範圍、5位區長及6位村里長訪談諮詢、111.10.13向台南市政府水利局業務人員諮詢，目標低地初步計有12處，與台南市政府討論確認符合逕流分攤最優先推動的區域有3處，包括鹽水區孫厝里、柳營區士林里、學甲區秀昌里，以及次優先推動1處北門區玉港里，均以逕流抑制及逕流暫存兩項來進行初步規劃。依據目標區位涉及之集水分區內進行土地資源盤點，分類為公共設施用地、公有非公用土地及公營事業土地，依據本案採用之定量降雨情境中的大豪雨(350mm/24hr)情境為例，以目標區域內最大淹水深的淹水量，進行目標區位分擔需求量之估算，經計算4處推動目標低地之分擔需求量與潛能量，分擔潛能量均超過需求量體，因此透過篩選之可利用土地做為逕流抑制與暫存。惟初步盤點篩選之各逕流分擔土地仍待本計畫第二年度(民國112年)與土地目的事業主管機協商、討論，確認配合意願及各土地之開發期程及分擔量體，以研擬逕流分擔方案，供後續逕流分擔計畫參考。

In recent years, rapid urban development and climate change have led to more severe variations in hydrological quantities. Broadening channel widths and heightening embankment heights have been unable to deal with the impact of various environmental changes, causing floods to occur more frequently than in the past. In the Jishuei River Basin, there were serious floods, such as Typhoon Morakot in 1998, 0823 heavy rain in 2018, and 0801 heavy rain in 2021. To solve the flooding problem in densely populated areas, The 5th River Management Office of the Water Resources Department implement “The Planning of Runoff Allocation for Jishuei River Basin,” based on the “Water Act” and “Runoff Allocation Technical Handbook”, to assess the feasibility of promoting runoff allocation. After the regulation projects are completely implemented, the six rivers which are administered by the central government and drainages in Jishuei River Basin won’t overfall, therefore, there is no target reach.In addition to referring to the current flooding simulation map by SOBEK model , we also do some jobs through interviews and consultations with 5 district chiefs and 6 village chiefs, and consultation with Tainan City Government Water Conservancy Bureau staff on Oct. 13th, 2022. Preliminary screening of 12 large-scale flooded areas has become possible target lowlands. After using the allocation base model to simulate, there are four target locations that meet the law and need to do runoff allocation, including Suncuoli in Yanyan District, Shilinli in Liuying District, Xiuchangli in Xuejia District and Yugangli in Beimen District, both runoff suppression and runoff temporary storage were used for preliminary planning.Making inventories of a land resource based on the catchment area of target locations, and excluding the lands in environmentally sensitive areas, special public facilities, and special base conditions, to calculate the potential amounts of runoff allocation which are supplied by each land. Also calculating the potential flooding amount of each target location in the 350mm/24hr scenario to find out the relationship between the potential amount of flooding and the potential amounts of runoff allocation.After calculating the shared demand and potential energy of the four promotion target lowlands, the shared potential energy exceeds the demand volume, so the available land that passes the screening is used as runoff suppression and temporary storage. In the second year of this project, it is still necessary to negotiate and discuss with the competent authority of the land and to confirm the development schedule of each land to develop a runoff allocation plan.