### h. Measures Against Illegally Moored Vessels in Rivers

Vessels illegally moored in rivers hampers flood control measures (interfere with the implementation of river works, obstruction of the downward flow during floods, damage to river administration facilities, etc.) and other aspects of river administration (water contamination by fuel leakage, obstruction of river usage, etc.). Such illegally moored vessels are directed to move to legal mooring facilities or removed.

In May 2013, the “Promotion Plan for Comprehensive Measures for the Appropriate Management and Improvement of the Operation Environment of Pleasure Boats” was created to resolve the issue of abandoned vessels (illegally moored vessels). In December 2013 the River Law enforcement ordinance was amended and the act of abandoning ships and other vessels was made illegal.

### i. Road Submergence Measures

Road underpasses in Tochigi and Hiroshima Prefectures were submerged in water due to the concentrated heavy rainfall that occurred in August and September of 2008, causing vehicles to sink. To prevent such accidents, information concerning submergence risk locations is shared with road administrators, police agencies, fire departments, and other relevant authorities. The framework for information exchange and passage prohibition is established, and the development and installation of submergence alert systems and monitoring facilities, as well as the publication of submergence risk locations that are publicized on the website, Note are promoted.

## (2) Countermeasures against Sediment-related Disasters

Japan has a steep geography and vulnerable geology over a wide area. In addition, Japan has a low number of plains and development of residential land has extended to hills and piedmont slopes along with the development of economy as well as the increase in population. As a result, there are about 520,000 areas vulnerable to sediment-related disasters such as debris flows, landslides, and slope failures where a lot of people are forced to live cheek by jowl with a risk of sediment-related disasters. There have been 1,000 cases of sediment-related disaster caused by heavy rain and earthquake annually on average in the past 10 years (from 2005 to 2014). In 2014, there were 1,184 cases, causing great damages such as 81 deaths.

In order to prevent and mitigate the damages by sediment-related disasters, combination of non-structural and structural measures, such as construction of sediment-related disaster prevention facilities and improvement and enhancement of early warning and evacuation systems are

Figure II-7-2-4

Effect of Sediment Control Dams against Heavy Rain in August 2014

Omach No.7 sediment control dam H=9.0m, L=32.0m

Source) MLIT

being promoted. The heavy rainfall in August 2014 caused a lot of sediment-related disasters in Hiroshima City, Hiroshima Prefecture, accompany significant damages such as 74 deaths. In Omachi area, Asaminami-ward, the existing sediment control dams blocked debris flows, succeeding in protection of 32 houses and 80 families living in apartments from sediment-related disasters. In addition, existing constructed sediment-related disaster prevention facilities exerted effects in various parts of all over the country.