Close

At the heart of the remote sensing industry

Remote Sensing Technology Center of Japan

Japanese
公式Facebookページ公式Facebookページ

Our Business

Disaster

Minimizing Flood Damage by Ascertaining the Movement, Spread and Amount of Water

Aya Yamamoto, Disaster Team Leade

Around 70% of disasters around the world can be attributed to water, such as through flooding. For successful rescue operations and in mitigating secondary disasters, quick and accurate ascertainment of such situations is an absolute must. SAR images allow observation even at night or in rough weather, to understand the movement, spread and amount of water. This not only contributes to emergency responses, mitigation of disasters and restoration work, but it can also contribute to risk aversion in disasters and in business.

Capturing the Flood in 3D → Paving the Way to Recovery and Restoration

When areas are flooded or submerged as the result of tsunamis or other disasters, ascertaining the locations and amount of the floods, and whether areas are accessible on foot or by car can save lives. After the Great East Japan Earthquake, information on flooded areas gained from images was provided to the Prime Minister’s Office and disaster prevention administrative agencies, contributing to restoration work.

Obtaining information not only on the surface area, but also the depth of inundation, will enable a more accurate estimation of the number of drainage pumps required. Therefore, research is currently being carried out on ways to obtain three-dimensional information. This technology could be used not only in Japan, but also throughout Asia.

This is a diagram of the flooded area after the Great East Japan Earthquake – the flooded area is enclosed in yellow. This information was provided to the Prime Minister’s Office and disaster prevention administrative agencies, contributing decision-making for how many pumps were required to drain water from the inundated areas, which areas had to be prioritized, and the formulation of restoration plans.

Predicting Floods Downstream from Conditions in Catchment Areas

Major rivers flow through Southeast Asia and South Asia causing frequent floods. An industrial park on the outskirts of Bangkok in Thailand was hit hard by a flood in November 2011, resulting in huge economic damage. By monitoring rivers from space, it is possible to prepare for these types of floods.

In the case of Thailand, it has been estimated that rain in river headwaters takes three to four months to reach downstream areas. This means that if we could grasp the water movements in the upper and middle reaches of rivers and streams through survey images to predict floods, we would be able to implement countermeasures such as inventory management and early shipment. Furthermore, when a flood actually occurs, surrounding areas can be surveyed to aid emergency decision-making by identifying the locations of inaccessible road sections, securing evacuation routes, and other measures.

Near the Rojana Industrial Park in Ayutthaya before the flood on August 27
Zoom

Near the Rojana Industrial Park in Ayutthaya before the flood on August 27

At the time of the flood on November 13
Zoom

At the time of the flood on November 13

Magnified image of the area around the industrial park on October 13
Zoom

Magnified image of the area around the industrial park on October 13

The Chao Phraya River flood in Central Thailand in 2011 claimed around 800 lives, and according to estimates by the World Bank, it caused damage amounting to around 3.5 trillion yen. ©JSI Produced by RESTEC

For Designing Insurance and Calculating the Amount of Damage

Data from surveys has accumulated over many decades, so we have data on the history of flooding in various regions. This data can be used to decide on suitable locations to build industrial parks and other facilities.

There are major opportunities in the future for the data to be used in insurance. Satellite images offer objective data over extensive areas, which could be used when designing insurance plans. Alternately, when a disaster actually strikes, images taken before and after the disaster can be compared to ascertain the state of damaged houses. Satellite data, such as a map of the flooded area, can be superimposed onto geographical information, such as the distribution of residences, to estimate the extent of the damage.

Diagram showing the estimated amount of damage ascertained by comparing images taken before and after the disaster
Zoom

Diagram showing the estimated amount of damage ascertained by comparing images taken before and after the disaster. Comparing high resolution satellite images taken pre- and post-disaster allows confirmation of whether houses have been partially damaged or completely destroyed, and even the number of houses involved. The image shows damage caused by a typhoon in the Tacloban area of Leyte Island. DigitalGlobe, Inc. All Rights Reserved.

Localized heavy rain such as “guerrilla rainstorms” have been occurring with greater frequency in recent years, and water damage is expected to become an increasingly common occurrence in the future. In rescue operations, life expectancy plummets beyond 72 hours after a disaster strikes. In emergency situations in or near Japan, “DAICHI-2” can carry out a survey within 12 hours, and provide images approximately one hour after the survey. Great expectations are held for it as a satellite that will save people’s lives. Moving forward, research and development will be carried out making use of past data to help predict disasters, and contribute to minimizing the damage from them by allowing people to make preparations in advance.