Water Disaster Prevention Model In Japan

Japan has faced hard lessons throughout the centuries, with natural disaster increasing from earthquakes, landslides, cyclones, floods, drought, and tsunamis.

Developing best practices for water supply and sanitation (WSS) services through an adaptive management to handle such issues. With increasing natural disasters WSS facilities and infrastructure have been vulnerable, impacting communities triggering the domino effect across interconnected infrastructure systems including public health and fire services.

Tokyo Metropolitan area has numerous parks designated as “disaster prevention parks”. The Kasai Rinkai park is a waterfront park with the largest high-tide evacuation site at 81 ha. It is designed to accommodate 270,000 people. It is a base for large rescue which include cooking facilities, emergency toilets, solar power light, roads that can accommodate large emergency vehicles and landing pads for helicopters.

The population of the Greater Tokyo has been living with floods for centuries and learned many lessons. With the change in our climates it has added another layer of challenges to flood prevention that is becoming vital to the population.

With a population of about 36 million, 50 percent of that population is living in the lowlands. Greater Tokyo is located on the alluvial floodplain which is made up to eight major rivers that flow through the Tokyo Basin.

The region is at risk of severe flooding that could be cause if a levee of a river is damaged during an earthquake. Similarly, storm surges and drainage problems can also result in flooding, typhoon events can lead a breach of a levee.

Disaster prevention has been at the forefront of the Greater Tokyo. Billions of dollars have been invested in flood preparation over the last centuries. Development of green and grey infrastructures have come to light becoming the most advance in the world. Regulating systems like the Kandagawa River Ring Road No.7. An underground regulated reservoir is an example of a grey infrastructure. This massive infrastructure has been designed to store up to 540,000 cubic meters of excess water, which is nearly 22 Olympic swimming pools. Five similar regulating reservoirs are under construction like the Shirakogawa River and the Furukawa River.

Upon completion of the reservoirs the capacity for Greater Tokyo will be 3.3 million cubic meters.

A series of underground tunnels called the ‘Metropolitan Area Outer Underground Discharge Channel’ or simply ‘Ryu-Q-Can’ can store an excess of rainwater. It is located 50 meters underground of Kasukabe city, 28 miles (45 km) north of Tokyo. The tunnels discharge into the Edo River. The project was completed in 2006 the cost was $2 billion USD. This significant investment was justified during the floods in 2014 that saved not only infrastructures but primary lives.

Green infrastructures projects like the Watarase-yusuichi is an artificial wetland that supports rich wildlife and acts as a retarding basin. It is located at the center of the Kanto plain, its functionality its to store water and temporarily retains river overflow, by preventing flooding elsewhere in the basin.

Constant communication with the Greater Population of the risks and options available for disaster response have been an important part of the flood prevention infrastructure. Campaigns regarding emergency water supply stations have been created at ~1.5-mile (2 km) radius intervals throughout the city.  Evacuation routes and large land areas reserved for evacuation points has been created like the Tokyo Rinkai Disaster Prevention Park officially opened in 2011 and encompasses 13.2ha to hold thousands of evacuees. In the case of a large-scale disaster, the Park acts as a central base of operations for disaster prevention in the Tokyo Metropolitan Area. It houses emergency response and medical facilities.

Like Tokyo many cities across Japan have been proactive to protect their infrastructure but also focusing on Prevention disaster by building infrastructure that could redirect the water safely preventing loss of lives and assets destruction. Information has been the key to train the population on disaster prevention. We cannot control Mother Nature, but we can still learn for our past lessons, so we do not repeat them like Japan has been doing.