Damage from flooding due to unexpectedly heavy rain is one of the risks that solar power plants near rivers in Japan face. In recent years, a number of regions in Japan have been hit one after another by torrential rains that are "the heaviest recorded" or "once in several hundred years." Rivers flooded and their levees collapsed due to the extreme weather conditions, damaging solar power plants in some cases.

Many rivers in the Tokachi region of Hokkaido were flooded on August 30 and 31 by Typhoon No. 10, which hit the Tohoku region and Hokkaido, and multiple mega (large-scale) solar power plants in the areas were damaged by the flooding.

The damage to a mega solar power plant in Nakajima Town of Obihiro City, one of such mega solar power plants, and the restoration carried out at the plant are covered in this article (Fig. 1).

Fig. 1: The power plant was damaged by Typhoon No. 10 in August 2016. A mega solar power plant in Nakajima Town, Obihiro City. The pictures were taken on September 6, 2016. (source: Nikkei BP)

Typhoon No. 10 brought heavy rain to a wide area of the Tokachi region including Obihiro City. Because of the rain, water levels of tributaries to the Tokachi River including the Satsunai, Tottabetsu, Sarubetsu, Toshibetsu, Otofuke, Memuro, Bisei, Pekerebetsu, Shin-Obihiro and Sahoro rivers as well as many other rivers exceeded the height of the levees, breaking them in some cases.

Muddy water flowed across the entire area, burying roads, houses and fields under mud. Bridges collapsed in some areas (Fig. 2). Because of the damage, many roads and railroads were blocked. In some areas, there was no running water for a long period because water pipes are routed under bridges.

Fig. 2: Many rivers including tributaries to the Tokachi River were flooded and many bridges collapsed. Railroads and many roads were blocked. The pictures were taken in September 2016 after the disaster. (source: Nikkei BP, excluding the picture on the top right, which was provided by a resident)

A large-scale slope failure occurred at the Nissho pass between the Tokachi region and the Hidaka region. The pass is on Route 274, a major route that connects central Hokkaido and eastern Hokkaido. The restoration work is still in progress. It is expected that traffic will be able to use the Nissho pass again by the end of October 2017.

The Tokachi region is one of the major agricultural areas in Japan, and vegetables produced in the region are delivered to all areas in Japan. Potatoes, onions, beets, red beans, etc were severely damaged by the typhoon.