Solar power plant on riverside washed away by flood
The disasters caused by the torrential rains in western Japan differed slightly between facilities in Hyogo and Hiroshima prefectures and those in Ehime and Okayama prefectures. The damage caused by the flooding of rivers, not landslides in mountains, was serious in Ehime and Okayama prefectures.
The Hijikawa River in Ehime Prefecture meanders along from upstream. Ozu Basin, situated at the middle of the river, tends to hold water, and the basin was also hit by flood disasters in the past.
The volume of water reached the capacity at Nomura Dam and Kanogawa Dam in the upstream part of the Hijikawa River due to the torrential rains in western Japan. An unprecedented amount of water flowed through the river downstream of the dams, because the water that flowed into the dams was released as an emergency measure. After the emergency release of the water, the Hijikawa River was flooded, resulting in major damage.
When we moved toward the upstream area from Ozu Basin, which was flooded across a wide area, we saw a large bridge (Taisei Bridge in Moriyama, Ozu City) that was destroyed by water and closed (Fig. 10). The bridge was supported by strong and large concrete foundations, but the foundations had fallen over or were broken. Parts of the iron bridge were scattered along the downstream area near the original location, indicating the power of the stream during the flood.
Along this area, roads and fields could be seen at elevations about 10m above the riverbed, and a small number of houses also stand in the area. There were traces of floodwaters having reached the high levels of the houses in these areas. Parts of the roads were eaten away along the riverside and destroyed.
There was a solar power plant that was destroyed by flowing water on the right side of the river in the upstream area near the bridge. The plant was also constructed on a site that is about 10m above the riverbed (Fig. 11).
The power plant was constructed on the site nearest the river in an area with higher elevation. A building that appears to be a warehouse and a house can be seen beside the plant. The buildings were being repaired.
The damaged solar power plant was a low-voltage plant for business use and three arrays were arranged in parallel to the river.
The arrays near the river did not retain their original forms and nearly all of the solar panels were gone, with only a few remaining on the mounting systems (Fig. 12). Some of the solar panels were pierced by their mounting systems, with large holes in them. It appears that the panels were torn off from the mounting systems and pierced due to the rapid flow of water caused by the flooding (Fig. 13).
However, the situation of the damage was different from solar power plants that were damaged by floods due to typhoons, such as the plants in Tokachi of Hokkaido and along the Kinugawa River in Ibaraki Prefecture. The equipment was nearly free from the adhesion of mud.
The mounting systems and solar panels at the low-voltage solar power plant for business use, which was constructed along the Hijikawa River and was damaged by the flood, were severely damaged, but there was nearly no mud adhered to them, nor was there a putrid smell. It looked like they had been washed by the water while being severely damaged by water pressure.
The fence was broken, but a yellow signboard was affixed to the mounting system. The signboard indicated that the power generation equipment was damaged and the parts were scattered, and prohibited approaching and touching the equipment. The signboard was put up after the disaster (Fig. 14).