Page 230 - Changing Living Spaces

Satoshi Murayama, Hiroko Nakamura, Noboru Higashi and Toru Terao

river extensions between 50 and 100 km include 42 river basins. There are
2,714 second-grade river basins, which include 7,081 rivers.7
According to the River Law, the second-grade basin system includes
rivers that are of public interest like the first-grade rivers, but these rivers
are administered by individual prefectures rather than by the Ministry.
The Takahama River, located in Takahama, Shimo-jima, one of the
Amakusa Islands in Kumamoto Prefecture, is a second-grade river located
only 3.5 km from its mountainous source. The Takahama is one of 81 ba-
sin systems, including 148 rivers managed and controlled by Kumamoto
Prefecture. The average length of the main rivers is 8.2 km; the longest
river is about 23 km long and the shortest is 1.6 km (Kumamoto Yearbook
2011). These small but diverse river systems, which exist in areas with
warmer climates in southwestern Japan, can help grow a variety of crops
and diverse vegetable cultivation cycles on a small scale throughout the
year (Tanaka 2010, 73).
Small-scale river management has never been thoroughly studied due
to the lack of historical material. However, our examination of the vil-
lage head’s records for the Takahama River uncovered rich material, such
as administrative diaries, pictorial maps depicting disaster damage, and
other original materials.
Regarding the 1803 flood (Kyowa 3), the village head’s historical sources
provide detailed information on heavy rains, the onset of heavy and per-
sistent rains that caused flooding, damage assessments, detailed pictorial
maps, and records of the reconstruction processes, including the number
of workers and their schedules in the two-year post-flood reconstruction
projects.

Flood, Drought, and Lack of Sunshine
Figure 5 shows the number of days on which rain-making rituals occurred
between 1793 and 1818 and the number of flooding events. Since there are
no records for five years (marked with an asterisk), we observed 21 years
of events. In only three of these 21 years were there neither rain-making
rituals nor flooding events. In 15 of the 21 years studied (71.4 percent),
prayer rituals for rain were performed almost every year. Water scarcity
appears to have been a major concern for Takahama residents. However,
water scarcity was often associated with flooding in 1801, 1804, and 1806

7 Ministry of Land, Infrastructure, Transport and Tourism Japan (n.d.-b). These
data were obtained on 30 April 2012.

228