The Sewer System Keeping Tokyo Dry

  • Tokyo
  • It’s well known that Japan’s population is gradually growing older, as the birth rate falls and the healthcare industry shifts to accommodate the aging population of the country. The country is also experiencing changes in population density, as the population of rural areas decline as people move to large city areas. Tokyo is no exception to this as one of the centers of economic activity in Japan. In addition to expanding and developing to accommodate a growing population, the metropolis is also preparing to accommodate the massive influx of visitors to the region for the 2020 Tokyo Olympics.

    The Greater Tokyo Area faces serious challenges when it comes to accommodating the needs of over 30 million people, and a large part of that has been dealing with the Japanese climate. In addition to the regular rainy season residents must endure every summer which can bring up to 16 centimeters of rainfall, Japan is frequently hit by typhoons as well. While most typhoons first form well to the south of Japan and don’t cause significant damage by the time they reach the Tokyo region, they do bring with them storm surges and bursts of rainfall to the metropolis. In the future as the Pacific rim is increasingly affected by climate change, the Tokyo area will be increasingly threatened by rising storm surges. Tokyo is a mostly urbanized region, meaning there are a lack of natural spaces where rainfall can be absorbed into the ground. This results in large amounts of water runoff, which needs a massive sewer system to service the Tokyo area. Learn about how Tokyo defends against flooding with this look at the massive infrastructure projects that serve this metropolis.

    Metropolitan Area Outer Underground Discharge Channel

    After the widespread damage caused throughout Japan by Typhoon Mireille in 1991, Japan’s storm system infrastructure was in need of major updates. The Tokyo region lies at the center of the Kanto Plain, a large flat region In the Mideast of Japan’s Honshu Island. Geographic tilts towards the Tokyo Bay result in the Tokyo region receiving a lot of water through river flows. Beginning in 1992, the Tokyo government underwent a massive construction project in the Saitama region to help stave off the threat of future flooding in the region. A series of massive underground tanks were constructed in order to store excess floodwater, which could then be pumped along a tunnel to drain out in the Edo river which runs along the Northeastern edge of the Tokyo Metropolitan Area. Nicknamed “G-Cans” this set of tanks which lie underground beneath the city of Kasukabe is a visually striking yet under-recognized part of the modern Tokyo cityscape.

    In spite of the imposing appearance of these storage tanks, the facility does offer tours to the public when conditions allow it. This can be a great opportunity to see another side of Tokyo that many people don’t get to see. Walking inside the cavernous interior of the main pressure-control tank, the sight can be quite thought-provoking as to just how large the solutions to common problems can be. While many people think of Tokyo as a massive city that is well-run and convenient to live in, it’s easy to take it all for granted without taking into account the works that support such a large city.

    You can learn more about how to reserve a tour of the the Underground Discharge Channel here.