地理研究

Now showing 1 - 4 of 4

臺灣東部河口地區之地形學研究
(地理學系, 1995-10-??) 石再添; 張瑞津; 林雪美; 張政亮; 劉明錡; 陳政典
The vincinity of the estuaries is one of the most populated area in the world. In order to ultilize the resources of this area more reasonably, the understanding of its geomorphological, hydrological and sedimentary characteristics becomes a main and basic task. Since estuary is located on the interface of river and sea, the morphology of estuary is influenced by the factors coming from both environments. The drainage basin area, shoreline length, shape factor, channel gradient, runoff, sediments and monthly discharge, etc. are factors coming from land, while the wind, current, wave and tide etc. coming from the sea. This study focuses on eleven estuaries of the eastern coast of Taiwan. Based on the stream slope, number of channels, discharge, etc., these estuaries can be divided into straight and braided pattern. The former has sandbars or spurs, such as Hualien Hsi, Hsiukuluan Hsi and Kangkou Hsi, while the latter have braided channels, sandy-gravel sediments and changeable sandbars, such as Hoping Hsi, Liwu Hsi and the estuaries in Taitung coastal area. The eastern coast is classified as wave-dominated type according to average wave height and tidal range. The wave impacting upon the area between Hoping Hsi and Hsiukuluan Hsi is severer. The forms of the estuaries in eastern Taiwan have significant seasonal change due to the seasonal differences of discharge, monsoon and typhoon. In the summer, the channels usually become wider and the sandbars are gentler and extended seaward for most estuaries. In the winter, however, these sandbars become narrower, steeper and extend toward right bank. The mouth of channels will be narrowed or even closed when typhoon coming. The forms of estuaries are stable in the long-term scale. Eleven estuaries have only slight change during the period from 1904 to 1989, moving back and forth within the distance of 250m. The channel migration of most estuaries, however, is obvious.
臺灣西南部河口地區之地形學研究
(地理學系, 1995-03-??) 石再添; 張瑞津; 林雪美; 張政亮; 劉明錡; 陳政典
The vincinity of the estuaries is one of the most populated area in the world. In order to ultilize the resource of this area more reasonably, the understanding of geomorphogical, hydrological and sedimentary characteristics becomes a main and basic task. Since estuary is located on the interface of river and sea, the morphology of estuary is influenced by the factors coming from both environments. The drainage basin area, shoreline length, shape factor, channel gradient, opening form, runoff, sediments, and monthly discharge etc. coming from the land. While the wind current, wave and tide etc. coming from the sea. This study area focuses on 20 estuaries of the south-western coast of Taiwan. The five of them are gravel estuaries and the rest are sandy. By correlation grain size of sandy estuaries has relationship with channel gradient below 100m, width of opening and shape factor. The forms of sand bar on estuaries are changed seasonly. Most of them has a tendency migrating southward due to northern moonsoon. The 20 estuaries can be classified into the wave dominated type, the tide dominated type and the runoff dominated type according average wave height, specific discharge and tidal range. Comparing the location of 20 estuaries during the period from 1904 to 1990(85 years). Most estuaries tend to migrate westward. The changes of estuaries are controlled by the intensity of wave and precipitation, the influence of reservior and hydraulic engineering and the changes of land use.
臺灣西部海岸沙丘之地形學研究
(地理學系, 1993-06-??) 石再添; 張瑞津; 張政亮; 林雪美; 連偵欽
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.
臺灣北部海岸沙丘之地形學研究
(地理學系, 1992-03-??) 石再添; 張瑞津; 林雪美; 張政亮; 連偵欽

地理研究

Browse

Filters

Settings

Sort By

Results per page

Search Results