SAKIGAKE管理人 Introduction
On July 5, 2017, the Kyushu Northern Heavy Rains, centered on Asakura City and Tōhō Village in Fukuoka Prefecture and Hita City in Oita Prefecture, caused devastating damage — claiming 42 lives and leaving more than 1,000 homes completely or partially destroyed. What made this disaster exceptional, however, was not only the scale of the damage. What set it apart was the fact that “unprecedented rainfall,” which shattered meteorological observation records one after another, continued to fall with a speed and intensity that existing warning systems simply could not keep up with.
In this article, we look back at the reality of the Kyushu Northern Heavy Rains and consider how the lesson that “observation and technology could not keep pace” can be applied to modern corporate disaster prevention and disaster risk management.
Rainfall That Kept Breaking Records
The most shocking aspect of this disaster was the sheer ferocity of the rainfall. Asakura City recorded an hourly rainfall of 129.5mm — among the largest ever observed in Japan at the time. Six-hour rainfall totals exceeded 500mm, and the phrase “first time in recorded history” was used across multiple locations, reflecting rainfall that vastly exceeded all existing assumptions.
This “unprecedented rainfall” overturned the very premises of hazard maps and evacuation standards. The flood and landslide danger zones shown on hazard maps at the time had been created based on past observational data. Yet the actual damage unfolded outside the bounds of those assumptions — with witness after witness reporting that “the damage reached places that had been considered safe.”
The Reality That Warning Systems “Could Not Keep Up”
Another defining feature of the Kyushu Northern Heavy Rains was the sudden intensity and highly localized nature of the rainfall. In Asakura City, the situation changed completely within just a few hours. Although the Japan Meteorological Agency issued a heavy rain special warning in the afternoon, river flooding and landslides had already begun in many areas — a situation in which the issuance of warnings could not keep up with the onset of damage.
This is not a story of negligence on the part of the Japan Meteorological Agency. The fundamental issue was that “an event of this rainfall intensity, this localized, in this short a time” was itself beyond what observation systems had anticipated. The very process of collecting rainfall data, analyzing it, and issuing warnings had not yet fully adapted to the reality that climate change was rendering “the conventional wisdom” obsolete.
Climate Change Is Making “Assumptions” Obsolete
It is no longer possible to treat this disaster as a one-off event. Since 2017, the expressions “first time in recorded history” and “once in several decades” have been used year after year — through the 2018 West Japan Heavy Rains, the 2019 Typhoon Hagibis, and the 2020 Kumamoto Heavy Rains.
The Japan Meteorological Agency and many other research institutions have pointed out that the frequency of intense short-duration rainfall events (linear precipitation zones) is increasing due to climate change. In other words, the observation networks, hazard maps, and evacuation standards designed based on past data are becoming obsolete at this very moment.
Implications for Corporate Disaster Prevention and BCP
The lessons of the Kyushu Northern Heavy Rains offer important perspectives not only for local governments and residents, but also for corporate disaster prevention planning and BCP development.
First, do not rely solely on “past hazard maps” as a basis for risk assessment. Flood and landslide danger zones are updated periodically based on new observational data and advances in technology. Developing a habit of cross-referencing the risks of your own locations, business partners, and logistics routes against the latest hazard maps is essential.
Second, recognize that a BCP premised on “acting after a warning is issued” will not hold. As the Kyushu Northern Heavy Rains demonstrated, there are cases in which damage begins before warnings are even issued. What is needed is a shift away from “act when a warning is issued” toward “make decisions early, based on reading ahead with weather radar and meteorological data.”
Third, establish a real-time monitoring system. To compensate for the limitations of existing observation technology, it is effective to have the infrastructure to grasp conditions around your own locations and partner sites in real time.Systems that monitor river water levels, rainfall, and ground movement in real time — and detect early warning signs on the ground — have a significant impact on the quality of initial response.
Introducing a Related Solution
One of the lessons taught by the Kyushu Northern Heavy Rains is the reality that “before warnings were issued, anomalies had already begun at the scene.” How can we detect localized ground changes that existing observation networks cannot capture, at an early stage? As one answer to that question, we would like to introduce the following solution handled by SAKIGAKE JAPAN.
DIPPS Cloud | Portable Landslide Monitoring Stake System
“DIPPS Cloud” is a portable monitoring stake system that detects subtle ground movement in real time simply by inserting stakes into slopes or cliffs, and notifies the cloud wirelessly.
Even in mountainous areas and on steep slopes — like those affected by the Kyushu Northern Heavy Rains — where mobile signals are hard to reach, a monitoring network can be built using satellite communication and Starlink connectivity. Even at sites where specialized technicians cannot be stationed, continuous 24-hour remote monitoring is possible. When an anomaly is detected, the management screen changes from green to red and an instant email notification is sent to relevant parties — making it possible to get ahead of warning signs at the field level, without waiting for an official warning to be issued.
- Easy installation: Just insert the stake into the ground — no large-scale construction required
- Centralized cloud management: Monitor multiple locations on a single screen from a PC or smartphone
- Works even outside mobile coverage: Mountain areas covered via satellite communication and Starlink connectivity
- Approximately 2-year battery life: Continuous monitoring with minimal maintenance burden
Compensating for the past limitation that “observation technology could not keep up” with real-time monitoring at the field level — DIPPS Cloud is a practical solution for exactly that purpose.
For details and inquiries, see below:
DIPPS Cloud Product Page
Conclusion
The Kyushu Northern Heavy Rains delivered a harsh lesson at the cost of 42 lives: “what we assumed until now is no longer a valid assumption.” This disaster, in which observation technology could not keep pace, pressed society as a whole to “update its premises” for disaster prevention in the age of climate change.
The era in which we can feel reassured by reasoning such as “there has been no major damage here in the past” or “it’s not on the hazard map” is over. As professionals in corporate disaster prevention consulting and disaster risk management, SAKIGAKE JAPAN is fully committed to supporting your disaster preparedness and BCP development.