Shimizu Corporation, which is involved in part of the Naka River embankment construction work damaged by Typhoon No. 19 in East Japan in 2028, has introduced "Weathernews for business," customized specifically for its river construction work sites, as a measure against flood damage. We asked Satoshi Tomiyama - san of Shimizu Corporation's Civil Engineering Tokyo Branch how the weather information is being used to improve safety measures and work efficiency at the river construction site.
We want to know in advance the rise in water levels around the site with accurate figures.
In order to carry out river embankment construction work safely and efficiently, it is important to accurately grasp the fluctuations of water levels in rivers as well as the weather. In principle, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) does not conduct river construction work during the flood season (June to October), when flood damage is most likely to occur. However, in light of recent advances in weather forecasting technology and other factors, we have placed orders for river construction projects in order to make construction possible even during periods of high water.
The area around the Koba district on the left bank of the Naka River, which will be the site of the embankment construction, has long seemed to be in the path of thunderstorms. Sudden rainfall increases the risk of rising water levels, which greatly affects the progress of the construction work. Therefore, in order to proceed with construction work while maintaining safety and improving efficiency, it was necessary to understand the risks with accurate figures, not just a sense of skin.
In particular, we had to watch out for rising water levels around the site due to rainfall upstream of the site. Rain falling outside the watershed does not affect the water level around the site, so it is very important to understand how much rain falls in the Naka River watershed. In the past, we used the website of the Ministry of Land, Infrastructure, Transport and Tourism and free weather forecast sites, but such detailed information is not available. In addition, there was a growing demand for not only live camera data, but also to consider how to respond based on forecasts of future changes, so we introduced "Weathernews for business," which specializes in river construction.
In addition, we had been aware of the frequent thunderstorms before the introduction of Weathernews for business, and the actual analysis of the data confirmed that many of the thunderstorms were coming from the Tochigi area. This allowed us to take concrete countermeasures," said Tomiyama - san.
Detecting the risk of rising water around the site by forecasting the average rainfall in the basin, which also takes into account rainfall upstream, and notifying the site supervisor to take immediate action to evacuate the site.
Weathernews for business, which is dedicated to river construction, provides "basin average rainfall" showing the amount of rainfall in the Naka River basin and "accumulated rainfall," which is the accumulated amount of average rainfall in the basin since the beginning of the rainfall. When the forecast exceeds the set value, the system notifies you with a "Caution" or "Warning" push notification.
I like to know how much the water level near the work site will rise in the coming hours, depending on rainfall tens of kilometers away," he said. It is dangerous if the water level exceeds the planned high water level set by the government, so we check to see if it has not. Basically, we try to be able to take evacuation action before the alert level is reached.
If there is a risk of heavy rain at night, we decide on a course of action, such as evacuating heavy equipment when the water level rises to this level, and inform the person in charge so that arrangements can be made even during the night. By deciding in advance, we can respond safely and quickly," says Tomiyama - san.
Not only Shimizu Construction's site supervisors, but also foremen for earthwork and frame work also use the system, and rain cloud radar and other data are used to coordinate daily work. They check the rain cloud radar on their smart phones and share information when there is a risk of rain. We sometimes issue instructions from a remote location, such as, 'It's going to rain in an hour, so let's stop construction and cover the site with a sheet right away.
In addition, when temperatures are high in the summer, we encourage workers to take a break once an hour in their tents to drink a sports drink to prevent heat stroke, and we check to see if anyone is feeling unwell. In winter, weather information is needed in addition to measures against heavy rain, such as using a sheet and heater when it is cold to prevent frost damage to fresh concrete during concrete placement.。
Deciding what to do based on highly accurate rain forecasts improves work efficiency and prevents construction schedule delays.
Shimizu Corporation has introduced "Weather News for Business" not only to strengthen safety measures, but also to improve work efficiency and reduce construction schedule delays. The company has also incorporated the system into its watershed timeline (disaster prevention action plan), which has given peace of mind to river construction clients. The ability to make decisions in advance about work to be done in the event of rain has helped to reduce wasteful work. For example, when it rains, the quality of the embankment goes down, and even if we continue with the work, we may have to redo it. This would reduce work efficiency and cost extra money. Now that construction can be suspended based on advance predictions, delays in the construction period can be minimized. Then, we are able to use the forecast of river flooding risk in our flood response timeline so that we can take appropriate disaster prevention measures. In general, small and medium-sized rivers with small catchment areas experience a rapid rise in water levels in a short period of time. In the case of the Naka River, there are numerous small rivers that flow into the Naka River, and it is very important to be able to forecast rainfall that covers them," said Tomiyama - san.
Potential Use of Meteorological Data for Underground Construction Work Involving Rainwater Inflow
Currently, "Weather News for Business" is used for river construction, but there is a possibility that it will be expanded to other fields in the future.
In the case of underground construction, sudden rainfall must have a significant impact on the work. Especially when working in deep locations, it is essential to avoid the risk of rainwater inflow from the surrounding area. If predictions can be made, it will be easier to take countermeasures in advance and improve safety.
Shimizu Corporation will continue to carry out river construction projects during the flood season with efficient construction planning based on weather data and appropriate safety management.
