圖書典藏及影音數位平台

河川測量為治理與管理必要工作，測量業務中，大斷面測量更屬必須定期辦理之項目，並可用以了解河道通洪能力、現有堤防高程及河道變動情形等，遂擬訂本次「104年度後龍溪水系大斷面測量暨河川特性分析計畫」計畫。

This project range included The Ho-Lung River mainstream and 8 branches. Main work were cross-section survey, bed material sampling and analysis, investigation for river crossing and flood control structures, which can calculate the river sedimentation changes and review the structures safety. The peak flow of mainstream and 8 branches followed up the volume of regulation master plans. The protect standard of Ho-Lung River and Lao-Tian-Liao River are 100 recurrence return period flood level. Others are 25 recurrence return period flood level. According to results of Surface Hydrological Survey, Most of the banks of the rivers can meet protection standards, only part of the banks elevations are inadequate. Moreover, there are 25 bridges which elevations of girder bottoms lower than 25 or 100 recurrence return period flood level. The left bank elevations of The Ho-Lung River section 71 to section 73 are meet 100 recurrence return period flood level. However, there are private lands and buildings on current announcement River Reservation Zone. It regulated the line of River Reservation Zone to gutter of road keep away from private lands. The fixed length of line of River Reservation Zone is 355 meters.

本計畫為經濟部水利署第二河川局於104年度執行之「後龍溪水系大斷面測量暨河川特性分析計畫」，範圍涵蓋後龍溪主流及八條主要支流，總長約91.8公里。計畫內容包含斷面樁補埋設、坐標高程測量、河道大斷面測量、跨河及防洪構造物調查、河床質採樣分析、水理模式建置，以及恭敬橋至汶水溪匯流口段的用地範圍局部變更。 計畫成果顯示，大部分河段的防洪構造物能達到預期保護標準，但部分河段高程不足。另有25座橋梁的梁底標高低於保護標準。計畫也分析了河道沖淤變化，並針對恭敬橋至汶水溪匯流口段因應社會經濟發展，修正了用地範圍線。