Learn Japanese how to prevent floods

Rain in place, in small areas often causes only slight flooding, but rain in other areas, upstream and upstream areas are often the cause of serious flooding.

Picture 1 of Learn Japanese how to prevent floods
Illustration. (Internet source)

The water naturally spills due to the low elevation of the soil and also because the drainage canals and rivers are not in time. It is also possible that the water rises high above the dyke bank or the dike, water overflows into residential areas, farming areas, low lying areas near the river causing flooding. Overflowing water often flows quickly (such as floodwater, dams upstream, rainwater from upstream of mountains and forests .) not only causes flooding to obstruct traffic but also swept everything on the way of country. This phenomenon is called flood or flash flood.

To avoid flooding

1 - Find a way to drive water from other areas to follow the path, the designated escape route, avoid to flow through residential areas, farming areas, low-lying areas.

2 - Enhancing the drainage capacity of canals and rivers to meet unusual cases such as flood discharge, dam failure upstream, heavy rain, widespread rain or storms.

Floods occur due to the natural low elevation of the land, because the drainage system (particularly the river channel system) does not catch up with the water flow.

These two principles are well understood, but in fact, in Vietnam, the flow of water from other areas has not been fully implemented, and the existing river channel system has not been able to handle unusual situations. of weather. For example, the Central Delta almost always suffers from flooding due to flooding, upstream dam failure, because of Truong Son upstream rainwater, when it is free overflow (the river has not overflowed, the dyke has not broken) , when the water overflows or breaks the dyke.

Experience the water treatment of Japanese people

Mountains in Japan occupy 4/5 of the land area, very few large plains, all residential areas, cultivation and production areas are close to the foot of the mountain, between the basin areas or on the escape route of rainwater Upstream mountains come.

The Japanese have applied the following treatment methods: in the basin area, people often dig canals close to the foot of the mountain to collect rainwater from the hills and mountains, leading to the rivers to drain, not to overflow Free access to residential areas or farming areas.

Japanese drainage rivers have a structure that allows for a soft response to the erratic weather. The dry season, and the days without rain, the river has very little water, the flow is about 50m wide, about 1 meter deep because rainwater escapes very quickly after rain. When it rains or storms, the river water rises very fast but still drains out safely thanks to the dike structure that can expand immediately the aperture of drainage (the width of the flow) as shown in the figure. Through the drawing, we see that the drainage capacity of rivers in Japan is much larger than that of Vietnam.

Moreover, river banks are still used to cultivate short-term crops to avoid flooding (extremely fertile, alluvial soil) or to use it as football, shuttlecock and park grounds. concrete with deep foundation underneath, safe, inexpensive, free from landslides.

Can we learn the Japanese experience to avoid the central disaster? Of course, there will be many obstacles and difficulties for nature, people, finance, technology . but it can certainly be done, slowly, to make each region until it can actively prevent flood.

Update 16 December 2018