Arakawa River (getting all philosophical)
The Arakawa River is a mighty system that starts in the mountains of north western Saitama prefecture and ends in Tokyo Bay. It is one of the main rivers that people here have had to battle over the years, as it often floods when there are heavy rains and typhoons. The map from ARA shows the risk of severe flooding in major parts of Tokyo: Up to 2 meters is indicated by pink colour on the official map.
The worst recent flood was in 1947, which prompted those in charge to build concrete embankments to try to avoid damage and save lives. In fact, the entire river that flows through Tokyo (with branches called Sumida and Kanda) is manmade.
The photo from 1910 shows similar damage.
As millions of people live near this river today, it is also an important park and recreation area, and many festivals are held aroud the year. "River Day" will take place July 7 (Tanabata Festival - celebrating the stars) on the Arakawa River and feature lots of events including outings on boats.
You can also visit the massive flood gates and there are education programs about the river and its special environment.
My train line, Saikyo line, and the Shinkansen line to Nagano, pass over the large bridge just north of Akabane, and the green parks along the banks are a welcome sight for sore Swedish eyes after all the concrete...
What 15 million people in Tokyo and Saitama may be unaware of is that all our good tap water comes from this river, way up in the cleaner regions, near Chichibu. Arakawa, the flowing river that is both a life-giver and a destroyer. Oupps, I'm getting all philosophical here. Time to click on "Publish" and let you read on.
Large map from Arakawa-Joryu River Management Office website (English).
Comments
In Hawaii, such channeling (typical Army Corp of Engineers response to such things) has resulted in soil as well as chemical fertilizer run off being sent out into the ocean, creating algae blooms and destroying coral reefs.
From that website it looks like they are having some success in improving the situation along the Arakawa. Good news.