Major Disaster Surveys
1. Field survey on the slope failure on National Road No. 57. caused by torrential rains which fell in thenorthern part of Kyushu in July 2012.
The torrential rains which had fallen in the northern part of Kyushu from July 11th to 14th, 2012 caused 11 slopes
to fail on National Road No. 57 in the Sakanashi district of Ichinomiya town of Aso City, Kumamoto Prefecture,
resulting in the total closure of the road. In response to a request from the Kyushu Road Maintenance Bureau, theRoad Research Department conducted a field survey to assess the scale of the devastation.

The survey wasfocused on the failed slopes, which had inflicted the most severe damage. The Road Maintenance Bureau
confirmed the effect of spring conditions and the fragmented rocks caught by the damaged rope netting covering
the slope. They also provided technical support on measures to lift the temporary traffic closure in that area.
Kazuhiko Mizutani, Research Coordinator for Road Structure
Road Department.

2. On-site technical advice on the sediment disasters in Kimotsuki town, Kagoshima Prefecture
The torrential rains triggered by the rain front from June 27 to 28th, 2012 in the mountain areas of Kimotsuki town,
Kagoshima Prefecture, caused a number of debris flows and slope failures leaving many houses damaged andtraffic routes closed with some villages totally isolated. In response to a request to conduct disaster survey from
Kagoshima Prefecture, the Sediment Control Research Department conducted a field survey in Kimotsuki town, as
well as a survey via helicopter on June 30th. We provided technical advices to Kagoshima Prefecture andKimotsuki town on the safe traffic control on National Road No. 448, the evacuation system, as well as emergency
measures.
Yasuhiro Nomura, Researcher
Erosion and Sediment Control Division
Research Center for Disaster Management

3. On-site technical advice on sediment disasters in Yufuin town, Yufu City, Oita Prefecture.
The torrential rains triggered by the rain front on the evening of July 1st, 2012 caused debris flows in the Gakuhon
River, which is a water system of the Oita River in Yufuin Town of Yufu City in Oita prefecture, inflicting damage
on houses, causing flooding and debris flows in the hot spring town located in the downstream of the river. Inresponse to a request from Oita Prefecture, the Sediment Control Research Department conducted a field survey
and one via helicopter on July 5th and 6th. We provided technical advices on how debris flows occurred, theeffect of the existing erosion-control dams, future evacuation measures, and maintenance of erosion-control
facilities, including removal of gravel accumulated on the existing erosion-control dams.
Atsushi Okamoto, HeadErosion and Sediment Control Division
Research Center for Disaster Management

4. On-site technical advice on the sediment disasters caused by torrential rains in Kinki districtThe torrential rains which had fallen in the southern part of Kyoto and Shiga Prefectures from August 13th to 14th,
2012 caused many slopes failures, generating debris flows, floods, etc. in Otsu City and Uji City, as well as in thesurrounding mountainous areas. The torrential rains had inflicted large scale damage on houses and loss of human
lives, and leaving some villages totally isolated. In response to a request for a disaster survey from Shiga
Prefecture and the Regional Development Bureau of Kinki District, the Sediment Control Department conducted afield survey from August 16th to 17th. We focused on the site where debris flows had occurred in Otsu City andUji City, providing technical advices on the evacuation system, as well as emergency measures to those localgovernments.
Yasuhiro Nomura, Researcher
Erosion and Sediment Control Division
Research Center for Disaster Management

5. On-site technical advice on the sediment disasters in Saijyo City, Ehime Prefecture
The slope on the left bank of the Tonotanigawa River, which is a water system of the Kamo River in Saijyo City,Ehime Prefecture collapsed on September 4th, 2012. The river channel was closed due to the landslide and thebridge over the Tono River on the Tozai Line of the city road was stricken by the disaster.

In response to arequest to the disaster survey, the Sediment Control Research Department conducted a field survey, providing
on-site technical advice. We checked the condition of the collapsedslopes and the closed river channel, examining
the possibilities of further slope failure. We advised of the need to conduct continuous monitoring of the slope
conditions, as well as the river water level of the water channel. In addition, we emphasized the need toformulate future policies based on the comprehensive assessment of reconstruction of the road and the water
channel, as well as the measures for the slope.
Yuki Okuyama, Researcher
Erosion and Sediment Control Division
Research Center for Disaster Management2