CTI Engineering Co., Ltd. has developed technology to analyze sediment deposition in rivers, using AI and aerial photographs.

CTI Engineering Co., Ltd., in collaboration with Yokohama City, has developed technology to automatically determine and analyze sediment deposition and vegetation overgrowth, using technologies including AI. Verification testing had been underway, with the goal of streamlining river management to reduce the risk of disasters occurring. Having recently concluded testing on September 27, 2023, CTI Engineering has released its results and launched a new service.

　

1. Development background

Yokohama City currently inspects sediment deposition and vegetation overgrowth by sending inspectors to sites to visually check conditions, in order to prevent inundation and overflow caused by flooding. During these inspections, personnel evaluate whether the downward flow section of the river is being maintained properly. However, there are so many rivers to manage, and these rivers are often very long. Inspecting them requires an enormous amount of work and time, and inspection results can vary depending on the skill and experience of the individual inspector.

　

2. Overview of results of verification testing using AI technology, etc.

In order to resolve these issues, we developed the following technologies and worked with Yokohama City to conduct verification testing.

(1) Automatically identify river areas with sediment deposition and vegetation overgrowth from aerial photographs with an accuracy of approximately 70%, utilizing AI image analysis technology

(2) Estimate sediment deposition with a measurement error of ±30%*1 by utilizing SfM*2 topography analysis technology and other technologies to generate 3D data of geographical features of rivers from aerial photographs*3

(3) Analyze amounts and changing trends in sediment deposition and vegetation overgrowth by using technologies (1) and (2) on current and past aerial photographs

　

*1. Evaluation in non-vegetation area (plant height must be excluded separately in vegetation areas)
*2. Structure from Motion: A means of reconstructing a 3D shape from images taken from multiple views
*3. Based on high-resolution aerial photographs with an overlap/sidelap ratio of 80% (provided by Yokohama City)

　

3. Obtained benefits

It was revealed that we were able to use existing aerial photographs*3 to quantitatively determine current sediment deposition and vegetation overgrowth conditions, as well as changes that have occurred over time. This new technology will also make it possible to determine unresolved issues that would prevent floodwater from flowing downstream safely and to identify areas that require urgent measures over a wide area, and should contribute significantly toward managing rivers more efficiently and effectively.

　

4. Future efforts

CTI Engineering is now expanding services all over Japan to automatically determine and analyze sediment deposition and vegetation overgrowth using this technology, in an effort to help bring river management to the next level.