Great flood disaster and the change of land use in the upper basin of River Totsukawa, Nara Prefecture

Abstract

The extent of land use in the upper basin of River Totsukawa, Nara prefecture, has been considerably conditioned by the great flood in 1889. So, this paper tries to trace the damage of land use in 1889 and to discuss the factors of it by the analysis of this disaster's reports published in 1891, some topography maps and land registered maps of each hamlet.The results obtained are as follows:1) The damage of land use was concentrated to the areas along the river, especially northern part of this basin.2) The damage of it was mainly by the great flood caused by many large dams which were arised from many landslides occured around these areas, under a sudden copious rainfall.3) The distribution of landslide shows that it was mainly depended upon the geological conditions. But, behind it, excessive use of production of forest land which were used for the fertilizer of increased paddy fields to pay new land taxation had advanced all over this area, where many paddy fields had been exploiting.4) The height of the flood got to 55 meters in this area. So many paddy and ordinary fields, houses, roads and forest which were located on the river terrace and slopes along river were carried away. Thus, the level of river bed was raised near the height of flood. The type of damage of land use in each hamlet was due to the degree of influence of this flood.5) A rise of river bed and landslide reduced the extent of the former land use. Thereafter reclamation had developed, but it was impossible to restore the former extent of land use.