曾文溪上游十號崩坍地之研究

Study of the No. 10 Landslide in Tsengwen Watershed

張石角(S. C. Chang) ； 蔡金郎(C. L. Tsai)

《中華水土保持學報》 4卷1期 (1973/06) Pp. 1-19

https://doi.org/10.29417/JCSWC.197306_4(1).0001

並列摘要

The No. 10 Landslide is located on the right bank of Tsengwen River near Tapan, Chiayi-hsien. It is the largest in scale in the watershed concerned, taking a tadpole-like form, and producing a great amount of sediment which will eventually be transported into the Tsengwen Reservoir. The landslide occurs on a steep slope (fault scarp?) just on the boundary between Tapan Formation and Nanchuang Formation, both of them are of Miocene rocks. The main sediment-producing area is rectangular in shape, restricted by competent sandstone beds on both sides. Evidently, the development of this landslide has been under strict control of geological structure as well as the lithology of the affected terrain. Further enlargement is predicted to point toward north, namely, along the strike of the weak shale beds in between the two competent sandstone beds. Three types of slope-failure have been recognized, i. e. rockfall, rockslide, and debris avalanche. Their occurrence sare closely related to the relation between the attitudes of the rocks and the slope on which the slope failure takes place. Technically, this landslide is difficult to deal with. Yet, after the river condition between Tapan village and the toe of the landslide having been improved, effective measures may be designed to treat each of the above mentioned types of slope-failure. Two samplers have been installed on the Tsengwen river, they are so designed that river water samples of the upper-and down-stream of the landslide can automatically be taken at the time when the river floods to a certain height. Results have revealed that the subwatershed of the Tsengwen River above the No. 10 landslide ca n be ignored as far as the sediment-producing rate is concerned.