無人機空拍應用於土壤沖蝕觀測之可行性評估

泥岩是一種沉積岩，它由細小岩石碎屑組成，顆粒大小介於黏土與粉砂之間，泥岩風化剝蝕，主要決定表面、地下水、邊坡傾斜角、時間、當地氣侯和透水性等因素，泥岩土壤含可溶性鹽成份很高，土壤成分中的交換性鈉及鹽離子易引起土層分散作用，使土壤膠體懸浮於水中，每逢雨季時，土壤便會受到逕流影響其穩定度，促使沖蝕災害的增加，加上泥岩地區的山坡坡度較陡，在物理及化學作用同時進行下，使泥岩表層不斷的剝落、滑下，新的岩層又裸露出來，反覆持續進行著，致使泥岩組織、構造、工程特性受風化作用的影響，植物不易在泥岩坡面上生長，工程構造物施作及保固不易，當雨水打擊土壤表面時，容易形成蝕溝沖蝕，導致至地表強烈侵蝕，引致各種泥流、邊坡侵蝕等土砂災害的發生。本研究為觀測泥岩之土壤沖蝕變化，於月世界地質公園佈設40支土壤沖蝕針，觀測期間2020年2月至2020年12月平均沖蝕量為5.563公分，最高沖蝕量可達18.5公分cm，且土壤沖蝕深度與累積雨量R2高達0.8868。本研究以DJI Phantom 4 Pro空拍機(以下簡稱P4P空拍機)收集每3個月高雄月世界地質公園泥岩地形變化之正射影像，搭配Trimble R8s GNSS Receiver衛星定位儀(以下簡稱R8s RTK)對地面控制點(共40點)進行定位，再以現地佈設之沖蝕針和固定構造物相對高程差異進行驗證，對於試驗區的泥岩地形變化作全面性的觀測，應用Pix4Dmapper程式計算出P4P空拍機搭配R8s RTK的精度誤差，自2020年2月至2020年12月間共取得4次空拍成果，研究結果顯示地面採樣距離GSD為0.0261公尺至0.0274公尺，而觀測土壤沖蝕深度的Z軸平均誤差為0.083公尺，並以萃取後之DSM成果與現地實際觀測數據作高程差異的判釋，以瞭解空拍機對於土壤沖蝕及地形變化之測量的可行性。

關鍵字

空拍機；泥岩；沖蝕針；土壤沖蝕

並列摘要

Mudstone is a sedimentary rock, which composed of tiny rock fragments, and the particle size is between silty clay, shale weathering mainly determined surface, ground water, the inclination angle of the slope, time, factors such as local climate and water permeability, containing a soluble salt ingredients mudstone high soil, soil salts and exchangeable sodium ion component can lead to soil dispersion, soil colloids suspended in water, during the rainy season, soil will by runoff affect its stability, promote erosion disasters increase, coupled with slopes steeper slope mudstone area in physics and chemistry at the same time, the surface layer of mudstone constantly falling off, slide down and expose new rock, continued with repeated, resulting in mudstone organization, construction, engineering properties under the influence of weathering, plant growth is not easy in the shale slope, engineering structures and facilities for the warranty is not easy, when rain hit the soil surface, easy to form a gully erosion, leading to strong surface erosion, earth and sand disaster caused by the occurrence of a variety of mudslides, slope erosion. In this study, to observe the changes in soil erosion of mudstone, 40 soil erosion pins were deployed in the Moon World Geopark. During the observation period, the average erosion amount of 2020/02-2020/12 was 5.563 cm, the highest erosion amount could reach 18.5 cm, and the soil erosion depth and accumulated rainfall R2 were as high as 0.8868. In this study, using the drone DJI Phantom 4 Pro (hereinafter referred to as P4P) to collect the monthly orthoimage for change of the terrain mudstone in Tianliao Moon World Landscape park in Kaohsiung, with Trimble R8s GNSS Receiver satellite positioning system (hereinafter referred to as R8s RTK) to ground control points (total of 40 points) is positioned, then the relative difference in elevation of the erosion and the needle is now routed to the fixed structure to verify, for mudstone topographical variation test area for comprehensive observation, the software Pix4Dmapper to analyze the errors of drone and R8s RTK, and the current data are actually observed as Interpretable elevation difference. A total of 10 aerial auction results were obtained from February to December in 2020. The results of the study show that the ground sampling distance (GSD) is between 0.0261 m to 0.0274 m, while the Z-axis average error is at 0.083 m, for measuring the drone for feasibility of soil erosion and the change in the topography.