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