A river water level prediction system using virtual
reality technology of NILIM received the “BestIndustrial Practical Application Award”
February 10th, 2023⚫

At the time of disaster, there is an indication that residents do not evacuate by a normalcy
bias: an assumption that they will not suffer a disaster.

⚫

For that reason, NILIM has developed a river water level prediction system with 3Dviewer using virtual reality technology with the aim of communicating a sense of urgency
and realism of the disaster more clearly to residents and preventing delays in evacuation.

⚫

NILM received the "Best Industrial Practical Application Award" in SAT TechnologyShowcase 2023* held in Tsukuba on January 26th, 2023.

⚫

This award is given to a presentation that is recognized as advanced application toindustrial technology out of approximately 100 presentations.
The introduction movie of this technology can be watched at the following URL.
http://www.nilim.go.jp/lab/feg/index.htm* SAT Technology Showcase 2023 is an interdisciplinary exchange meeting for
researchers and engineers in the Tokyo metropolitan area and elsewhere to bring andshare their latest research results, ideas and technologies each other.
https://www.science-academy.jp/showcase/22/index.html

12023/2/20
The 9th International Conference on Flood Management

Developing a river water level
prediction system with 3D viewer
using virtual reality technology
National Institute for Land and Infrastructure Management
Department of Rivers, Water Cycle Division

Y. MOROOKA, S.TSUCHIYA and T. TAKESHITA

国土交通省Outline

国総研

1. Introduction
2. Developing technology notes
1. Operability
2. Visual effects
3. Accessibility
3. Developed technology

4. Summary
5. Future plans2

Introduction ~ Research Background~
Kanto-Tohoku torrential
rain disaster (2015)

Kinu river

About 4,300 people were rescued
due to the delay in evacuating※Quoted and added from the website of MLIT

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The Social Infrastructure
Improvement Council (2015)“Promotion of the technology development
for improving the accuracy of floodforecasting”

The Social Infrastructure
Improvement Council (2018)“To improve the sophistication of flood
forecasting and enhance provision of flood
forecasts and water level information”

Developed by NILIM“Flood Risk Line” (2019~)

Color-coded
Flood-Risk levels.

Water-level forecast information【Introduced Technologies】
・High accuracy river channel models
・Particle filters, etc.

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Introduction ~ Research Background~

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Flood risk line (Under improvement)
BeforeAfterUtilize JMA ensemble forecasts
Water level

Water level prediction considering inundation

6 h into
the future

36 h into
the future

81 h into
the future

Developing technologies for longer and more accurate forecast information
Cabinet Office’s study group (2022)
・Residents do not evacuate appropriately even if evacuation information isissued due to insufficient communication of a sense of urgency and realism of
the disaster.

・Flood Risk Line also needs to be improved to more clearly convey the sense ofurgency and realism of a disaster to residents in an easy-to-understand way.

・We developed technology for 3D displays of visualizing Flood Risk Line.
Confirm the validity and feasibility of the VR display

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Introduction ~Preliminary investigation~

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① Effectiveness of VR display of forecast information for evacuation
Example of a casePrevious researches

Kakimoto et al.（2020）

Installed webcams
in dangerous areas

・ Residents’ evacuation behavior wasfacilitated by a sense of urgency andrealism of the disaster situation atthe site.

Fujimura et al.（2019）※Quoted and added from the website of Cabinet Office・ Approximately 10,000 accesses/month
have been reported.

Residents want to check thevideo of the dangerous places.

・ There is an evacuation promotion effecton the visual recognition of flood byevacuation experiments using VR.

The 3D forecast information
leads to facilitation of evacuationand communicates the dangers
of disasters to residents.

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Introduction ~Preliminary investigation~② Examples of the use of VR technology
in the field of flood prevention
3D display ofhazard map andtopography

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③ Possibility of collecting 3D dataWeatherForecasting 3DDisplay

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Disaster Experience VR(※Including AR and MR)

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Total 30 cases
Classification of existing case studies
using VR to promote evacuation behavior

・ 3D display of forecast information is
only for the purpose of safe aircraft
operations.
No efforts have been seen to display riverwater level forecast information using VR.

※Quoted from the website of the Arakawa
Karyu River Office, MLIT

3D jurisdiction map（Arakawa 12KP）
https://www.youtube.com/watch?v=Mvg0P6X
632o

・ This map and 3D urban model will be
developed for all government managedrivers.

3D data necessary for thistechnology development will be
prepared in the near future.

6Points to note when developing technology

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① Operability (speed of information display)② Visual effects (to enhance the sense of urgency and realism)③ Accessibility (accessible on various devices and operating systems)
3D terrain mesh createdDirectly from LP data

3D terrain meshafter retopology

The number ofpolygons was
reduced fromabout 10 million
to about 30,000
per 30 km2

Re-topology(reattachment of the surface to fit the shape)

The amount of data is reduced to 1/500, and thetime required to draw one screen is reduced fromabout 1 minute to about 0.1 of a second.

Move to one distancemarker to the rightabout 200m
about 400m

Duplicate data (red dots)
are not loaded again whenswitching screens.
Reduced display load7

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Points to note when developing technology

国総研① Operability (speed of information display)② Visual effects (to enhance the sense of urgency and realism)③ Accessibility (accessible on various devices and operating systems)

Before adding effects

Fujimura et al.(2019) VR experiment results：
Evacuation rate increased during times whenthe "river turbidity is remarkably" visible.

Effects related to the sense of realism

・Water surface turbidity
・Water surface oscillation
・Cloudy weather
・Rainfall etc.

After adding effects

Zoom
The dangerous water level
The water levelfor evacuation

Effects related to thesense of urgency
8国土交通省

Points to note when developing technology

国総研① Operability (speed of information display)② Visual effects (to enhance the sense of urgency and realism)③ Accessibility (accessible on various devices and operating systems)
Drone photographyBackground image

Laser Profiler data

3D water surface models
Created fromthe results ofFlood Risk Line

Input

OutputDevelop VR environment with “Unity”,
a multi-platform game engine

WebGL format (standard specification
for VR display in a web browser) 9国土交通省

Developed operation screen for VR display
Switching between left and right bank

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Move to upstream anddownstream distance markers
Current time

Change of viewpoint and zoom
in/out with mouse operation

Dangerous
water level
Water levelfor evacuation
Water level
18.3 mTop ofthe bank

16.2 m15.8 mSwitching display time(current time to 6 hours ahead )Time

CurrentDistanceMarkers

3 h into
the future

Move to another distance markers

13.1 m6 h into
the future10Demonstration video

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Advantages and issues of VR display

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① Advantages other than conveying a sense of urgency and realism
CCTV camera image

VR display image

Comparison at the same time at night（2022/9/19 0:00 Yamakuni river 26.8KP）・ Even if it is difficult to confirm the local situation by CCTV cameras,
the VR display enables visualization of the flood situation.
・ VR display can freely change the angle of view, zoom, and switch
display to areas where CCTV cameras are not installed.
12Advantages and issues of VR display

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② Visual effects of VR are not enough・ There are not enough effects in the VR simulation.
It is necessary to create effects for normal conditions (sunny, nospray, etc.) and switch effects between normal and flood conditions.

・ Visual effects on the sense of urgency and realism of the disaster areunclear.
Gathering opinions from local government and feedback on thistechnology to make new improvement.

Example of opinions”Hard to see how many hours
later the dangerous waterlevel will be exceeded”.

Sep.28, 2022

”We want to know how close tothe dangerous water level”.
13Advantages and issues of VR display

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③ Issues related to forecasting accuracy and risk communication during
disaster・ We can’t imagine easily what happens to residents when forecasts differ
significantly from actual conditions.

Limit the display to sections where a certain level prediction accuracy
can be confirmed.

・ Server downtime due to high network traffic during disaster.
Addition of function to output clipped video with limited data volume
and video duration.

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Summary

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We have developed a technology for 3D display of river water level
forecasts using VR technology.

The results of this study will be compiled into a draft specification
to enable the addition of a VR display function as an optional
function for Flood Risk Line.
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Future plans

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・ Implementation of improvements to current issues.
(For example, improving the quality of VR.)

Normal condition

Flood condition

・ Longer forecasting time (from 6 hours ahead to 36 hoursahead), etc.

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