臺灣西部海岸沙丘之地形學研究

Abstract

Coastal sand dunes are widely distributed along the western coast of Taiwan from Touchien Hsi to Erhjen Hsi. Based on maps work, airphoto interpretation, particle size analysis, field investigation, etc, the study results are summarized as follows: 1. The form and the magnitude of the western coastal sand dunes have close relationship with the source of 13 rivers' sand supply, alongshore current and wave action, power and direction of wind, terrains, rainfall, evaporation and vegetation. 2. The coastal dunes develop well on riversides of Chung Kang His, Holung Hsi, Choshui Hsi and offshore bars along Chianan coast. Two principal types of these dunefield may be distinguished, namely, active dunes and stabilized dunes. The two dunefield types contain a variety of dune features, such as transverse dunes, barchans, longitudinal dunes, and dome dune etc. 3. The grain sizes of beach and dune sand are quite uniform. The Md φ and δ φ on average of the dune sand is smaller than the beach sand. This shows that wave process is stronger than wind process. 4. Comparing the maps published in 1926 and 1984. the change of coastal dunes is clear. Because the dunefield was used as fishery or watermelon and sugarcane planting, most of the sand dunes were leveled off entirely. Some of the residual sand dune still exist at present fixed by windbreak forest. For sand dunes have the function of protecting coasts, they had better be well-planned and well-used so as to main-tain the sustainable utilization of land souces.