Noda City, Japan -A little bit of thumping sound and you can hear an echo emanating from the immense underground discharge channel – an engineering marvel built to alleviate the rising of flood waters in the Naka and Ayase river basins.
It is the world's largest underground flood water diversion facility built in Kasukabe city in Saitama Prefecture, to mitigate overflowing of the city's major waterways and rivers during rain and typhoon seasons.
Over 30,000 homes are now protected from the rising flood waters, which has been devastated since early times due to its changed flow channel caused by flooding of the two rivers in the area.
This vast underground channel named, The Metropolitan Area Outer Underground Discharge Channel, is part of an extensive 5.2 miles that took 13 years and 4,450 cu. ft of concrete at a cost of 238 billion yen ($2 billion) to build. The system includes five huge water shafts 230 feet deep and has a radius of 100 feet that feeds to the pressure-adjusting water tank and pump system.
This enormous underground space is 256 feet wide and 72 feet meters deep. The 59 pillars, standing 59 feet high and each weighing 500 tons, hold up the ceiling of this underground temple. The entire system is situated north of Tokyo.
The Metropolitan Area Outer Underground Discharge Channel
This project completed in 2006 best captures how Japan’s advance engineering combined with its economic success have been directed to solve some of its longstanding problems, be it environmental or natural disasters.
It is a public infrastructure investment that the people and the community greatly benefit from.
Fortunately, Palauans have been spared from the occasional flood waters as residential areas are traditionally situated closer to the water than farther inland. However, that doesn’t mean that the population doesn’t experience flooding of some sort.
Urbanization has been the greatest cause of flooding in Palau. In Palau’s main commercial center of Koror where close to 70 percent of the population live are well aware of the problem. As the largest town, Koror’s main highway receives special treatment with attention on road resurfacing, street lights, and road signage but during rainstorm flooding occurs.
This is because the road drainage system – ditches and culverts have been blocked by debris with no constant maintenance. Large sections of the road become prone to flooding as storm water from building and homes collects into large pools making large sections of the road nearly impassable by vehicles or by foot.
Palau doesn’t need Japan’s technological prowess or large public financing to solve its road flooding problem but a simple maintenance schedule would do wonders than any engineering knowhow.
(Ongerung Kambes Kesolei was in Japan as part of the 2018 Pacific-Caribbean Journalists Program from Oct. 20-31. He participated in the program with senior journalists from Fiji, American Samoa,Trinidad & Tobago, and St. Vincent & The Grenadines.)