Characteristics of Irrigation of Reclaimed Land in the Early 19th Century on Fan Tableland: A Case of Kashobara, Southern Part of Saijo Basin, Central Hiroshima, SW Japan

This study clarified the characteristics of irrigation system of reclaimed land in the early 19th century on fan tableland in Kashobara, southern part of Saijo Basin, Hiroshima, SW Japan based on physical geographical and literature historical methods. The most important to open the reclaimed land on fan tableland for rice fields in those days was to obtain sufficient water for agriculture through a newly-built irrigation system. I identified the relationship the dirrigation system and landform using the 5m grid Digital Elevation Model, air photos and mapping of irrigation pattern by handy GPS. Descriptions of official documents relating the reclaimed land written by the chief of village, and information of detailed drawings of planning of the reclaimed land in those days, provided us to understand the then planner's intention to collect and distribute the waters to cultivated land on tableland. This fact contributed to development of transdisciplinary lesson between geography and Japanese history for school education

Detailed mapping on active fault in developing region and its significance : A case study of Nepal

In this paper, we introduce the detailed mapping on active fault in Nepal as a leading work on reduction for seismic hazard in developing region. Active faulting, is an origin of large earthquakes, causes tremendous damage for human life when it happens. However, developing countries have little understanding for nature of active fault and significance of the detailed active fault map for seismic hazard. We firstly show how to make the map. Then we enumerate two weak cases against faulting movement from the point of view of spatial relationship between the active fault and the infrastructures such as hydro-power station, the power lines and the bridge on the highway. Any infrastructure in Nepal is not considered to be located away from the fault. Some are too close to the fault to be dangerous if it moves. Judging from natural and social condition of Nepal, we propose significance of detailed active fault map for developing region. The map provides the precious location of the fault to keep the public infrastructure away from the fault. Because the number of infrastructure in developing resion is rarely and the function is subject to be concentrated at an existing infrastructure, if the fault moves, the damage hits not only the seismic area, but also its distant place extensively. As the map lets the local people to understand where the great earthquake is likely to happen, the map will be regards as a tool of the enlightenment of the seismic hazard

Mapping of an abandoned irrigation channel in the southern part of Saijo Basin, Higashi-Hiroshima city, Southwest Japan, and its significance

東広島市西条盆地南部に位置する柏原（かしょうばら）地区は，段丘面上に広がる近世後期の新田開発地である。柏原地区の農業用水を確保するために中の峠（たお）池（現深道池）が造築されたが，池の集水域が狭く慢性的に水不足であった。そのため，池の集水域と異なる小田山川の集水域内の山麓に用水路を築き，中の峠池に水をもたらしてきた。現在は別の導水トンネル（中の峠隧道）ができたため，この用水路は30 年以上前に放棄されている。本研究では，現地調査によって用水路の構造のマッピングを行い，さらに古文書の解読によって造築の経緯の一端を明らかにした。本研究は，郷土の発展の痕跡である歴史的な文化財を後世に伝えるだけでなく，今後増加すると考えられる放棄用水路のマッピングの先駆的な事例として意義があると考えられる。A village of Kashobara was established by new reclamation work for rice field in early 19th-century in the southern part of Saijo Basin, Higashi-Hiroshima City, Southwest Japan. Local villagers built a pond named "Nakanotao pond" for irrigation close to the village. Because its water was always little due to its too small catchment area, it was very difficult to crop rice properly. Then local villagers made an irrigation channel to put additional water into the pond from out of its catchment. As a newly tunnel for irrigation was made in 90 years ago, the channel has been abandoned over 30 years. The objects of this study are 1) mapping of the abandoned channel by geophysical field survey, and 2) analysis of historical record related the abandoned channel. This study contributes a record of local heritage of civil engineering, and is regarded as a pioneer study for mapping of abandoned channel, numbers of which will increase in Japan.本稿の内容の一部は，2018年度地理科学学会春季学術大会（2018年6月2日，於広島大学大学院文学研究科）にて口頭発表を行った