CTI Engineering has developed the Sediment Trapping Screen, a new erosion-control facility that reduces flood damage: a new measure for responding to sediment runoff likely to be caused by light or moderate rainfall following heavy rainfall disasters

To help prevent disasters due to fine-grained sediment runoff, a common problem after landslides, we have jointly developed the Sediment Trapping Screen (patent pending), an erosion-control facility with new functions, in collaboration with SHIBATA INDUSTRIAL CO., LTD. (head office: Akashi City, Hyogo Prefecture; CEO: Atsuki Shibata).

　

This technology will be used in new residential areas located in mountainous areas as well as mountain villages and other places where there are not enough drainage canals to help prevent or at least reduce flood damage due to the flow of fine-grained sediment following heavy rainfall disasters.

　

1. Background
One characteristic of landslides in recent years is that, in addition to large-scale landslides caused by debris flow, etc. during heavy rainfall, there is frequently flood damage that interferes with daily life, including flooding above and under floors in downstream villages, due to the long-term flow of fine-grained sediment (bed load) as a result of subsequent rainfall. Erosion-control facilities developed in the past are not sufficient for handling bed load, which is one of the causes of such flood damage.
　

To respond to the continuous flow of such fine-grained sediment and resolve issues faced by past erosion-control facilities in terms of maintenance management, etc., we developed our new Sediment Trapping Screen.

　

2. Technology features
Our Sediment Trapping Screen has new functions that enable it to efficiently trap fine-grained bed-load sediment, which is likely to continuously flow following heavy rainfall and was difficult to effectively respond to by using past erosion-control weirs intended to handle the flow of debris.

　

　

Fig. 1 Sediment Trapping Screen

　

　

Our new facility makes it easy to handle maintenance management, including removing trapped sediment, and it also offers outstanding ease of construction and cost performance thanks to the use of precast or lightweight materials.

　

In addition, the functional materials we used include ultra-high molecular weight polyethylene netting, which offers outstanding fine-grained sediment trapping performance, and we conducted static load testing* using life-size equipment to confirm that our Sediment Trapping Screen is strong and durable enough for sediment trapping.

* Our test specifically involved setting up our Sediment Trapping Screen in an exposed outdoor environment under the maximum intended load for one year.

　

Fig. 2 Sediment Trapping Screen structure　　　

　

Fig. 3 Maximum polyethylene netting extension rate

　

　

3. Future outlook
SHIBATA INDUSTRIAL CO., LTD., with whom we jointly developed the Sediment Trapping Screen, has commercialized and started selling this new product (patent pending).
　

As part of our company's initiatives to reduce the severity of increasingly diverse landslide risks, we will consider how to effectively apply our recently developed Sediment Trapping Screen in various target regions and deploy it in collaboration with SHIBATA INDUSTRIAL CO., LTD. to contribute to the prevention or at least the reduction of flood damage due to sediment caused by light or moderate rainfall following heavy rainfall disasters.