Research on the micro landforms of the coastal and alluvial lowlands in relation to the Holocene geo-environment.

本研究旨在阐明晚全新世河流滨海平原微地貌的形成和演化与沉积环境的关系。对诺比平原的微地貌和沉积物进行了详细的分析。阐明了平原的演变与平原考古遗址分布的关系，阐明了平原地貌不是按照沉积面积的变化而是有序发展的，而是逐步发展的。还研究了河流河道和沉积面积的变化与亚哈吉河低地埋藏森林的关系。研究了柬埔寨湄公河三角洲上游详细的微地貌及其与洪水的关系。还研究了湄公河三角洲东北部的海岸变化和红树林的演化。在距今海岸线50~80公里处的内陆可见红树林泥炭，其年龄为6000~7000cal BP，河流沉积覆盖红树林，形成河流地貌。以2004年12月26日斯马特拉大地震引发的海啸灾害为例，研究了微地貌对洪灾和海啸灾害的影响。泰国南干沿海平原上冲和倒冲的海啸流明显不同。平原上厚厚的海啸沉积在凹陷中被视为山脊之间的燕子。

Objective of this research is to clarify the formation and evolution of micro landforms of the riverine coastal plains in relation to the sedimentary environments in late Holocene. Detail analysis of the micro landforms and the sediments were done on the Nobi plain. Evolution of the plain was clarified in relation to the distribution of archaeological sites in the plain, and it is clarified that the landforms of the plain developed not in order but step by step according to the change of deposition area. Change of the river course and deposition area was also studied in relation to the buried forest in the Yahagi river lowland.Detail micro landform and its relation to the flooding were studied in the upper stream of the Mekong River delta in Cambodia. Coastal change and evolution of mangroves were also studied in the northeastern Mekong River delta. Mangrove peat can be seen in the area around 50-80 km inland from the present coastline and the ages of them are 6000-7000 cal BR After 6000 cal BP, deposition of fluvial sediments covered mangroves and formed fluvial landforms in the area.Effects of the micro landforms to the flooding and tsunami disaster were also studied especially on the case of the tsunami disaster caused by the giant earthquake off Smatra on December 26, 2004. Run up and back wash tsunami flows were distinguished in the Nam Khem coastal plain, Thailand. Thick tsunami deposits in the plain are seen in the depression as swales between the ridges.