圖書典藏及影音數位平台

朴子溪支流獅子頭溪及濁水溪(含番子路科溪)治理基本計畫於民國83年公告，而清水溪(含頂埔溪)治理基本計畫則於民國81年公告，至今皆已逾30餘年。考量氣候變遷衝擊影響，過去治理計畫所定計畫洪水量與治理策略、治理工程亟待重新審視檢討，故辦理此治理規劃檢討。 本計畫旨在對朴子溪支流進行全面審查和分析，同時建立相關調查資料，確定總體規劃和管理方針，完成河流系統治理規劃審查工作，為後續的治理工程工作奠定基礎，保護居民免受洪災威脅，減少經濟損失，並緩解易澇地區的洪澇災害問題。 本次分析計算結果流量值大於前期報告分析中所採用的值。考慮到安全因素、近期降雨模式以及總體管理要求等，採納本次分析結果為水力分析中使用的峰值流量的基礎。 本次規劃檢討各河段現況兩岸河防建造物布設量相較於前期規劃而言已完備許多，因此在現況水理上無法滿足25年重現期距洪水位之斷面皆位於獅子頭溪，包含斷面27右岸、斷面35-1~37左岸、斷面35-1~37右岸、斷面42-2~斷面42-3兩岸、斷面45及46兩岸及斷面49及50兩岸等處，其中下游河段係受牛稠溪外水位影響導致溢淹，而中上游河段則因包括通水斷面不足、橋梁梁底高程不足造成水位壅高所致，其餘四條支流現況皆能滿足25年重現期距保護標準。 對於經河道整治後仍無法達到 25 年設計洪水位的河段（包括橫斷面 35-1 至 37 的兩岸，以及橫斷面 46 和 49 的兩岸）： 1. 橫斷面 35-1 至 37 的左岸，因其後方有一條道路，預計以建造擋土牆（堤壩）以抵禦洪水。 2. 橫斷面 35-1 至 37 的右岸，現有河道在彎道處過於突出，容易導致水流沖擊左岸的凹岸部分，須後移現有擋土牆以拓寬河道。 3. 橫斷面46及49斷面兩岸，現有擋土牆已存在，預計透過抬高擋土牆進行治理，抬高高度依本報告中之設計堰頂高程。 鑑於傳統的管理規劃僅根據河川溢流限值評估防洪結構的有效性，而忽略了預防因這些結構失效而引發的災害。本計畫納入了風險評估結果，以了解高風險河段的災害成因。考慮到現有的環境資源，將制定可行的應對措施和計劃，以實現減災目標。本計畫各河段的主要危險因子源自於河川彎曲或流速過大造成的結構侵蝕。為了減少水力侵蝕並提高結構基礎的安全性，未來的措施可能包括河道整治以加厚河岸平台，加強護岸/堤壩，或保護堤腳基礎以防止水流直接衝擊。

The regulation project of river management plans for the Puzi River tributaries (Shizitou Stream and Zhuoshui River, including Fanzi Road Ke Stream) were announced in 1994, while the fundamental river management plan for the Qingshui Stream (including Dingpu Stream) was announced in 1992. Both plans are now over 30 years old. Considering the impact of climate change, the design flood discharge, management strategies, and engineering works defined in the original management plans urgently need to be reviewed and reassessed. Therefore, this management planning review is being conducted. The purpose of this project is to conduct a comprehensive review and analysis of the Puzi River tributaries, concurrently establish relevant investigation data, determine the overall planning and management policies, and complete the work related to the river system management planning review. This serves as the basis for subsequent remediation engineering works, aiming to protect residents from flood threats, reduce financial losses, and alleviate the problem of areas prone to flooding. The results of this analysis show that the calculated flow values are greater than those adopted in the previous report's analysis. Based on factors such as safety considerations, recent rainfall patterns, and overall management requirements, the values from this current analysis are adopted as the basis for the peak flow rate used in the hydraulic analysis. The protection standard for all five tributaries in this project is set at a 25-year return period. Based on the current hydraulic analysis, the locations where the 25-year return period flood water level cannot be met are all situated along the Shizitou Stream. These include: the right bank of cross-section 27; the left and right banks of cross-sections 35-1 through 37; both banks of cross-sections 42-2 through 42-3; both banks of cross-sections 45 and 46; and both banks of cross-sections 49 and 50. The issues in the middle and upper reaches of this stream are primarily caused by insufficient flow cross-section area and insufficient bridge deck clearance (low girder elevation), leading to water level back-up. The remaining four tributaries are currently able to meet the 25-year return period protection standard. For sections where the 25-year return period design flood level still cannot be met even after river channel regularization (including both banks of cross-sections 35-1 to 37, and both banks of cross-sections 46 and 49): 1. For the left bank of cross-sections 35-1 to 37, there is an existing road behind, so construction of a retaining wall (levee) will be budgeted to resist the flood. 2. For the right bank of cross-sections 35-1 to 37, the existing channel is too prominent at the bend, which easily causes the flow to impact the concave section of the left bank. Therefore, the existing retaining wall must be set back to widen the river channel. 3. For the latter two locations (cross-sections 46 and 49, both banks), existing retaining walls are already in place, so the management will be carried out by raising the retaining walls. The height of the raising will be based on the design crest elevation determined in this study. Given that conventional management planning only assesses the adequacy of flood control structures based on river overflow limits, it neglects the prevention of disasters caused by the failure of these structures. This project incorporates the results of a risk assessment to understand the causes of disasters in high-risk river sections. Considering available environmental resources, feasible countermeasures and plans will be formulated to achieve the goal of disaster mitigation. The primary risk factors in the various river sections of this project stem from the erosion of structures caused by river sinuosity or excessive flow velocity. To reduce hydraulic erosion and enhance the safety of structure foundations, future measures may include river channel regularization to thicken the riparian bench, strengthening the revetment/levee, or protecting the foundation of the embankment toe to prevent direct water impact.