Decarbonization Initiatives in the Construction of Port Breakwaters
—Application of research results to a project—
Figure-1 Conceptual perspective drawing
of the Kushiro Port Island Breakwater
(Modified from a perspective drawing provided
by the Kushiro Development and Construction
Department of the Hokkaido Regional
Development Bureau.)
1. Introduction
Blue carbon has gained much attention in recent years as we work to realize a decarbonized society. Blue carbon refers to the CO2 stored in seaweeds that sink to the seabed without decomposing after they die, resulting in the long-term storage of that CO2.
“Biological symbiotic port structures”, such as those with kelp forests, are included in “blue infrastructure”, and the Ministry of Land, Infrastructure, Transport and Tourism is promoting the expansion of such infrastructure. Based on the Vision for the Technological Development of Fishing Ports and Other Ports in Hokkaido1), the Hokkaido Regional Development Bureau is promoting efforts to create kelp forests by utilizing dredged sediment* to construct shallow areas inside breakwaters (inside ports) to which sunlight can easily penetrate (Figure-1).。
In establishing shallow areas at the back of breakwaters (inside ports), the Civil Engineering Research Institute for Cold Region has long studied how stable is the covering material in shallow areas where waves strike strongly, how well these areas reduce the heights of waves propagating through them, and how these structures affect seaweed growth in these shallow areas. The results are being used for projects such as the creation of a shallow area inside the Kushiro Port Island Breakwater.
Figure-2 Cross-section of
a composite breakwater
Figure-3 Cross-section of a breakwater
covered with wave-dissipating blocks
Photo-1 Aerial photo of the area used for
a demonstration experiment on a kelp forest at
the Kushiro Port Island Breakwater (June 2021)
Provided by the Kushiro Development and
Construction Department of
the Hokkaido Regional Development Bureau
Photo-2 Sargassum fulvellum has grown to
the water surface in the shallow area at
the back of West Breakwater
at Hakodate Port (February 2024)
Provided by Japan Blue Economy Research Group PT
2. What is the structure of a breakwater?
（１）A composite breakwater
Concrete caissons (boxes) are installed on top of a Rubble mound foundation (a base) of riprap with a diameter of about 50 cm on the seabed (Figure-2). Large work vessels are required for construction. Japan’s offshore construction technology makes it possible to construct structures even in deep water.
（２）A breakwater covered with wave-dissipating blocks
In some breakwaters that are protected by wave-dissipating blocks, the blocks are piled on the outside of the composite breakwater (outside of the port) (Figure-3) . Such breakwaters have several merits. The wave force acting on the breakwater body (the caissons) is reduced, and the waves that overtop the breakwater and those that are reflected by the breakwater can be dissipated.
３．Example of the creation of a shallow area at the back of the breakwater
（１）The Island Breakwater at Kushiro Port
The project plan2) for the island breakwater at Kushiro Port utilizes dredged sediment to create a shallow area 100 m wide by 1,100 m long the back of the breakwater. Monitoring at the 100-m-long demonstration experiment area (Photo-1) revealed that about 1.9 t of CO2 can be stored per year using this facility. Based on the monitoring, it is expected that about 22.9 t of CO2 will be stored per year after the completion of the project3).
（２）The West Breakwater at Hakodate Port
A project for constructing a shallow area was implemented at West Breakwater.at Hakodate Port Inside the breakwater, an 85-m-wide by 710-m-long shallow area was constructed using dredged sediment mixed with Calsia*, a soil improvement agent4). Seaweeds, including Sargassum fulvellum, were found to be thriving in the shallow area (Photo-2) of this facility, which proved that CO2 has been stored effectively.
*the raw material name for a converter-type blast furnace slag
References
1) Port and Harbor Construction Division and Fisheries Division, Hokkaido Regional Development Bureau: Vision for the Technological Development of Fishing Ports and Other Ports in Hokkaido—Declaration on Technological Development for Creating Sustainable Northern Ports, 2021. https://www.hkd.mlit.go.jp/ky/kk/kou_ken/ud49g7000000jypy.html (As of March 14, 2024)
2) YAMAMOTO Narimi, TAKANO Wataru, MOTOMATSU Keiichiro: Survey and Study Focusing on Blue Carbon at Kushiro Port, The 66th (FY 2022) Hokkaido Development Technology Conference, 2023.
3) MIZUKI Kentaro, ABE Hisashi, SAKOU Akinori: Evaluation of Blue Carbon Storage in the Kelp Harvesting Area, The 66th (FY 2022) Hokkaido Development Technology Conference, 2023.
4) OTAKA Keisuke, KUDO Hirofumi, DOI Yoshikazu: Effectiveness of Fill along the Back of Breakwater—Promotion of Blue Infrastructures, The 66th (FY 2022) Hokkaido Development Technology Conference, 2023.
(Contact : Port and Coast Research Team,CERI)
International Contribution by ICHARM
-Support for the Establishment and Activities of the Platform on Water Resilience and Disasters-
Photo 1. Participants in the 4th Platform
Plenary Meeting in the Philippines
(From the Facebook page of Philippine DOST)
Figure 1. Functional overview of OSS-SR
in the Philippines
Photo 2. Signing ceremony of
the tripartite agreement
between DOST, DSSC,
and ICHARM (online) (Jan. 24th, 2024)
Bottom row center: DOST XI Director Anthony Sales
Right: DSSC President Augie Fuentes
(From DOST XI Facebook)
Photo 3. Participants in the 1st Platform
Plenary Meeting in Thailand
(From the Facebook page of
the Office of National Water Resources
(ONWR), Thailand)
As one of its major international activities, the International Centre for Water Hazard and Risk Management under the auspices of UNESCO (ICHARM) at PWRI serves as the secretariat of the International Flood Initiative (IFI). The IFI is a collaborative framework of international organizations including UNESCO and the World Meteorological Organization that promotes effective flood management globally.
As part of the IFI’s activities, we support the establishment and activities of the Platform on Water Resilience and Disasters (“the Platform”) in collaboration with government agencies and other organizations in various countries. The Platform serves as a national framework for collaboration by various government agencies (e.g., weather, flood control, evacuation, disaster information) and related organizations (e.g., watershed management agencies, community representatives, NPOs, universities, and media) involved in water-related disasters. Specifically, utilizing the Online Synthesis System for Sustainability and Resilience (OSS-SR)1), it facilitates discussions to draft, formulate, and implement plans for flood control and climate change adaptation measures in each country. It also focuses on training “facilitators” who act as intermediaries, bridging scientific knowledge and policymakers.
We have supported the establishment and activities of platforms in the Philippines, Sri Lanka, Indonesia, Myanmar, Pakistan, and Thailand. In Davao City, the Philippines, in particular, four platform meetings were held with the participation of all relevant agencies, including the Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), the Department of Science and Technology (DOST), the Department of Public Works and Highways (DPWH), and the University of the Philippines Los Baños (UPLB). We have also been working with local agency officials to build a real-time flood monitoring and forecasting system using OSS-SR, to assess climate change impacts, and to train “facilitators” using e-learning (see Figure 1).
We are also collaborating with local institutions, highlighted by the Davao Regional Development Council’s adoption of resolution No. 42, which formalized its cooperation with ICHARM in developing OSS-SR and training facilitators. In FY 2023, following discussions with the president of Davao del Sur State College (DSSC), a tripartite agreement was signed between DOST XI (Davao Bureau), DSSC, and ICHARM to initiate activities in Digos City, a neighboring city of Davao City. Future initiatives include the deployment of OSS-SR in the Province of Davao del Sur, developing water hazard prediction systems for the Digos River, and providing inclusive water education to diverse community members.
In Thailand, ICHARM has conducted various initiatives, including activities under the Typhoon Committee2) and the SATREPS project3). To accelerate further interagency collaboration and implementation of the latest science and technology, the country’s water agencies decided to launch a new platform and held its inaugural meeting on Mar. 25th, 2024.
Platform meetings were also held in Sri Lanka and Indonesia in Mar. and Apr. 2024, respectively, to reinvigorate activities following a period of reduced engagement due to the COVID-19 pandemic.
ICHARM remains committed to actively supporting these platform activities, aiming to mitigate water-related disaster damage in the respective countries.
1) OSS-SR (Online Synthesis System for Sustainable Resilience): A system that can archive data owned by each institution, build models, and perform analysis, utilizing DIAS, a high-performance, large-capacity computer system promoted by the University of Tokyo’s Global Environmental Data Commons.
2) Typhoon Committee: A community of governments established in 1968 to promote and coordinate planning and implementation measures to minimize human and property damage due to typhoons in the Asia-Pacific region. ICHARM's senior researcher serves as the chair of the Working Group on Hydrology .
3) SATREPS project: A program to promote international joint research between Japan and developing countries to solve global-scale issues, in collaboration with the Japan Science and Technology Agency (JST), which has expertise in providing research grants to domestic research institutions, and the Japan International Cooperation Agency (JICA), which provides technical cooperation with developing countries.