Characteristics of heavy rainfall in Tochigi and Fukushima prefecture on August 26th to 31th, 1998

Motoyuki Ushiyama

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The local severe rain disaster by the local severe rain of Bai-u front occurred in August 26th to 31th, 1997, on Fukushima and Tochigi prefecture. We examined about the characteristic of this local severe rain by AMeDAS data(1978-1998). The total precipitation of this rainfall event(Aug.,26 to 31) was 1253 mm in Nasu and 656 mm in Shirakawa. These records were the highest records respectively within 21 years and 48 years. The distribution type of this case resembled an average distribution type in August. Therefore, this local severe rain didn't occur in the extraordinary place. The most intense rain occurred in the earlier about 12 hours compared with the flat area on the mountain area. It is possible that this thing caused being behind in the disaster countermeasures.

Key word: disaster of local severe rain, distribution of precipitation, continuous precipitation, Mt. Nasu.

Fig.1 Distribution of rainfall observation station of Japan Meteorological Agency around Shirakawa city
 is the position of rainfall observation station and station name
MapFan II(C)Increment P Corp.


Fig.2 Distribution of total precipitation from August 26th to August 31th


Fig.3 Distribution of mean monthly precipitation on August


Fig.4 Temporal variations in Nasu and Happogahara (Aug. 26, 1998 to Aug. 31)


Fig.5 Temporal variations in Shirakawa and Ootawara (Aug. 26, 1998 to Aug. 31)

Table 3 Extremes of daily precipitation and continuous precipitation in Shirakawa (1951-1998)
Ranking Date Daily
precipitation
(mm)		 Date Continuous
precipitation
(mm)
1 61/06/27 177.5 77/08/21 289.0
2 58/09/26 175.7 64/09/02 287.2
3 71/08/31 162.0 61/06.30 286.3
4 61/09/10 151.2 64/09/01 283.7
5 66/06/28 150.8 77/08/20 283.5
6 91/09/19 150.0 71/09/12 278.5
7 82/09/12 145.0 64/08/31 275.4
8 86/08/04 125.0 64/08/30 273.2
9 71/09/06 124.0 58/07/28 272.5
10 58/07/22 118.7 64/08/29 271.5
98/08/27 267.0 361.0
98/08/28 65.0 429.0
98/08/29 114.0 533.0
98/08/30 102.0 644.0
98/08/31 11.0 656.0

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