Topography Change near River Mouth according to Mid/Long-Term Change of Sea Level and River Sediment Discharge, and its Response to Tidal Flat Ecosystem

本研究由四个部分组成。一个是受全球变暖等影响，海水温度上升的研究，近年来日本海岸的海平面上升令人担忧。然后，根据潮汐资料和地壳运动资料考察了整个日本海岸的中长期海平面变化特征，了解到西日本海平面上升速度大。第二种是考察河口地形变化的因素。通过对国土交通部定期测量数据的EOF分析和河流地形变化的二维数值模拟，研究了河口地形的长期变化特征和河流泥沙特征。第三部分对莫诺贝河、有明海等河口及周边海域的一次流沙特征进行了详细的野外观测，提出了一种新的野外观测技术。在第四部分中，我们成功地建立了生境适宜度指数（HSI）模型，该模型通过几种物理环境特征来估计潮滩底栖动物的环境适宜度。

This research is composed of four researches. The one is a research that the seawater temperature rises by the influence such as global warming, and the rise of the sea level in a Japanese coast is feared in recent years. Then, it has been understood that the rising speed of the sea level of West Japan is large as a result of examining the characteristic of mid/long-term sea-level variation for the whole area of a Japanese coast based on the tide data and the diastrophism data. The second is the one that we examined the factor of the mouth of a river topography change. Long-term variation properties of river mouth topography and characteristics of river sediment were examined through the EOF analysis of the surveying data that had been regularly measured by the Ministry of Land, Infrastructure and Transport and a two-dimensional numerical simulation of a river topography change. In the third one, we executes detailed field observations for characteristics of a sand drift in the river mouth and the surrounding ocean area for the Monobe river and Ariake Sea, etc., and proposes a new field observation technique. In the fourth one, we succeeded in the development of the Habitat Suitability Index (HSI) model by which the suitability degree of environment for benthos in a tidal flat is estimated from several physical environmental characteristics.