泥岩邊坡紋溝發育過程與機制

The Process and Mechanism of Rill Development on Mudstone Slope A Case Study in Taiwan

楊啟見(Ci-Jian Yang) ； 林俊全(Jiun-Chuan Lin) ； 鄭遠昌(Yuan-Chang Cheng)

《地理學報》 81期 (2016/06) Pp. 27-42

https://doi.org/10.6161/jgs.2016.81.02

摘要

本研究旨在模擬泥岩風化層的水力侵蝕過程，考量野外實驗難以模擬泥岩風化層的侵蝕過程，故於室內實驗設計沖蝕水槽，實驗樣本取自臺灣臺南市龍崎區牛埔水土保持教室，利用樣區所採集的泥岩風化層為材料，模擬地表逕流侵蝕，配合地面三維雷射掃描儀測繪，重建逐時變化的侵蝕過程與量測侵蝕量，由於地面光達可以提供高解析度的數值高程模型，因此可偵測到紋溝形成等微地形的變化，有助於討論泥岩風化層侵蝕地形的演育過程與機制。研究結果顯示：1. 泥岩邊坡風化層在逕流量固定下，侵蝕量呈非線性成長，原因在侵蝕型態轉變。侵蝕階段依照侵蝕型態與侵蝕量變化可分為四個階段，一、片狀侵蝕期；二、紋溝侵蝕期。三、崩塌期；四、穩定期。2. 泥裂在片狀侵蝕期能匯集逕流，泥裂發達的邊坡會可造成較高的侵蝕量與侵蝕速率。3. 泥裂會影響紋溝的發育時間與位置。4. 泥岩侵蝕具有穩定階段，此時侵蝕量與侵蝕速率均下降或持平，推測泥岩邊坡具有侵蝕限制。

關鍵字

泥岩 ； 地面三維雷射掃描儀 ； 水槽 ； 紋溝發育 ； 泥裂

並列摘要

This study observes the process and understands the influence of micromorphology by using laboratory flume experiments. The mudstone is sampled from the mudstone area in Long-Chi district, south western Taiwan, which is famous for the Gutinken formation. To obtain the volume of mudstone erosion and terrain changes during experiments, ground LIDAR is used to scan the sample flume surface several times. The ground LIDAR data provide high-resolution elevation values to demonstrate micromorphology change, assisting the understanding of the process and mechanism of water erosion on mudstone slopes. The following conclusions can be drawn from the analysical results. (1) Due to the change of erosion pattern, the erosive volume has non-linear growth, and even the runoff is fixed. Erosion can be classified into four types according to the erosion pattern and volume: (a) sheet erosion; (b) rill erosion; (c) failure; (d) stable. (2) Mudcracks can gather runoff in the of sheet erosion stage. Hence, slopes with mudcracks cause more soil loss than the non-mudcracked slopes. Furthermore, slopes with mudcracks cause more soil loss than the non-mudcracked slopes. (3) Mudcracks influence the spatial distribution and trigger time of the rill. (4) The erosive volume and rate decrease in the stable stage, indicating that a erosion limitation controls the evolution of mudstone slopes.

並列關鍵字

mudstone ； ground LIDAR ； flume ； rill development ； mudcracks

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