Research on geoenvironmental dynamics of coastal and alluvial lowlands

本文从自然灾害和环境变化的角度探讨了冲积海岸低地的演化和地质环境。冲积低地的地貌在冰期后随着海平面和气候的变化而发展。以津加鲁平原、努比平原和越后平原为目标平原，用10^3 ~ 10^2年的时间讨论了冲积低地的沉积速率和演化过程。结果发现，武和火山喷发对岩崎河及其支流形成的冲积平原的地质环境变化有很大的影响。Nobi和Tenryu平原的洪泛平原沉积是在全新世海侵高潮后进行的。在越后平原，沉积速率几乎与全新世海平面上升速率相当。Nobi平原天然堤防的沉降速率约为洪盆的10倍。对泰国和爪哇平原的洪泛区进行了洪水条件和微地貌研究。基于RADARSAT图像，分析了洪水水位与地形的关系。在此基础上，阐明了泰国中部洪泛区洪水条件与水稻种植格局的季节变化之间的良好关系。基于SRTM-DEM数据和卫星影像对越南中部土本冲积平原进行了地貌分类。利用地理信息系统阐明了平原地形与洪水状况之间的良好关系。此外，还对泰国中下游地区硫酸酸性土壤的形成进行了探讨。明确了全新世中期沿延伸海岸线发育的红树林与酸性硫酸盐土壤的分布有关。如上所述，本文阐明了冲积低地形成的时空动力学，揭示了冲积平原和滨海平原的地质环境动力学与低地自然灾害和人类居住等各种问题的关系。此外，本研究的几项研究是在东南亚地区进行的，其结果可能会对当地人民有所贡献。少

In this study, we discussed on the evolution and geo-environment of alluvial and coastal lowlands in relation to natural disasters and environmental change. The landforms of the alluvial lowlands have developed in response to sealevel and climate changes during the postglacial age.The Tsugaru, Noubi and Echigo plains were the target plains, and the sedimentation rate and the evolution process of the alluvial lowlands were discussed by 10^3 or 10^2 years.As a result, it was found that the eruption of Towada had a great influence on the geo-environmental change in the flood plain formed by the Iwaki river and its tributaties. The aggradation of flood plain sediments in the Nobi and Tenryu plains progressed after the culmination of the Holocene transgression. In the Echigo plain, the rate of the sedimentation is almost equivalent to the Holocene sealevel rise. The sedimentation rate of natural levees in the Nobi plain is about 10 times larger than that of the flood basin.Flood condition a … More nd micro-landforms of the flood plain were studied about in the plains of Thailand and Java. Flood level based on the images of RADARSAT was analyzed in relation to the topography. Based on the analysis, good relationship between flood condition and the seasonal variation of the paddy-rice planting pattern were clarified in the flood plain of central Thailand.Landform classification based on SRTM-DEM data and satellite images were done in the Thu Bon alluvial plain, central Vietnam. Good relationship between the flood condition and the topography of the plain were clarified and shown with GIS. Furthermore, formation of the acid sulfate acid soil in the Lower Central Plain, Thailand was discussed. And it was made clear that the distribution of acid sulfate soils is related to the distribution of mangrove forest which developed along the extended coastline during the middle Holocene embayment.As mentioned above, time and spatial dynamics in relation to the formation of alluvial lowland were clarified, and the relationship between the geo-environmental dynamics in alluvial and coastal plains and various issues as to natural disasters and human habitation in the lowlands were shown in this study. In addition, several researches for this study were done particularly in Southeastern Asian areas and the result may be able to contribute to the local people. Less