圖書典藏及影音數位平台

天然河川於颱洪事件過後，伴隨而來則是河道沖淤之變化，其中常有出現土石堆積狀況，近期尤以「莫拉克」颱洪災後造成河道嚴重淤積，因此為避免影響河道通洪能力，則需即時仰賴河川管理單位積極進行疏濬工程。由於傳統上河道沖刷可藉由沖刷磚或其他沖刷監測儀器埋設等方式來掌握河道沖刷情況，然而颱洪事件後河道淤積情況則需採測量技術，針對淤積土石部份河段辦理淤積及疏濬前、中、後河道變化之測量作業，而此等作業方式較為費時，而尚無有效方法可即時掌握河道淤積情況。 爰此，本計畫以濁水溪水流泥砂為研究範例，評估國內、外之現地人工主動式及自動化河道淤積觀測方法（如3D-LiDAR等方式），並結合不同時期影像判釋 (如福衛二號衛星影像與無人載具空拍影像)、地形沖淤變化量測等資料分析河床變化，並藉由數值模式進行河床穩定及沖淤特性分析，建立觀測值與河道淤積量之關係，以達到強化流域土砂移動監測，定期檢視河川淤砂，適時疏濬之目標。

The applicability and cost analysis of the measured methods for the river-bed elevation, which were applicated in Zhuoshui River, are the major purpose of this reaserch. Based on eight Principles, the Confluence region of the Chenyoulan River and Junken River was chosed for the field test area to analyze the applicability for Ground-based Lidar and four-rotary-wing aircraft. Whole the measured methods for the river-bed elevation are separated into two types: Remote sensing analysis methods and direct measured methods on ground. The best measured method is based on different requirement and field conditions such as the area, slop of eiver bed. The error of the elevation between measured results by Ground-based Lidar and field data could be smaller than 2 cm. The average error of the elevation between the analysed results by four-rotary-wing aircraft and field data was about 40 cm. It showed that the applicability of the UAVS to measured both the downstream (gentle slope) and upstream (deep slop) river bed. The Ground-based Lidar for the smaller area (<10km2) and Airbone Lidar for the large area (>10km2) were susgested both based on the cost consideration and precision requirement. Based on the consideration of the work time, the big UAV and four-rotary-wing aircraft were susgested for the river-bed elevation measured in a small rigion (<10km2) on the doenstream rivers and upstream rivers respectively. Using the airphoto imagery to analyze the river-bed elevation was susgested for the large area (>10km2) to minimize the work time. Four-rotary-wing aircraft could be used fro the tracffic-blocked and small area of the upstream river bed . The CCHE-2D model was used to simlulate the river-bed changing of the filed-tested river region during April 2008 to December 2008. Typhoon KALMAEGI, typhoon FUNG-WONG, typhoon SINLAKU and typhoon JANGMI were in this simulation period. The average error between the simulation results and field measured data was about 30 cm. It showed that the the parameters set in the model could be used to simulate the natural change of filed-tested river region without artificial dredge. Four easy-deposition areas of the Zhuoshui River were determined in this research. The Ground-based Lidar was susgested for the elevation measurement of cross-section of river bed to evaluate the river-bed changing conditions summarily between two bridges. If there was obvious deposition conditions between some cross sections, a suitable measured method for region-measurement would be chosed from whole methods in this research.