臺灣北部河口地區之地形學研究

Abstract

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 geomorphological, hydrological and sedimentary characteristics becomes a fundamental task. Since estuary is located on the interface of river and sea, its morphology 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 the factors from land, while the wind, current, wave and tide etc. are the factors from the sea. This study focuses on the 19 estuaries of the northern coast of Taiwan. According to the principal process of estuarine area, these estuaries can be classified as fluvial, tidal or wind wave dominated type. Based on the field observation, the depositional forms of these estuaries have significant seasonal change due to the seasonal differences of river discharge, wind, tidal range, wave and typhoon freqency. On the other hand, the result of the comparison of six sets of topographical maps from 1904 to 1989, shows that the seaward and landward migration of most estuaries is unstable.