Pioneering technology in simulating the journey of ocean plastic waste
Plastic waste washed ashore in Nha Trang (left) and floating debris near Cau Da port (right)
Marine plastic waste, particularly large-sized debris (macro plastic debris - MPD), is severely affecting marine ecosystems and global environmental security. The issue has been repeatedly discussed at the United Nations Environment Council, underscoring the urgency and transboundary scale of plastic pollution. However, detailed field data to determine the origin, transport pathways, and dispersion mechanisms of MPD - especially in estuarine and riverine coastal areas - remain very limited, particularly in developing countries.
In response to this urgent need, MSc. Nguyen Duc Thinh and the research team from the Institute of Oceanography – Vietnam Academy of Science and Technology (VAST) conducted the project: “Research and assessment of the transport and dispersion processes of macro-sized plastic waste in estuarine and coastal areas of the South Central region” (code: VAST06.05/22-23). The study contributes valuable field data and provides an important scientific foundation for developing policies and solutions to mitigate plastic pollution in Vietnam’s coastal areas.
Sharing on the research methodology, MSc. Nguyen Duc Thinh explained: Unlike many current studies that rely mainly on pure computer simulations, the team combined field data with modern modeling technologies. Specifically, they used GPS-equipped drifters to directly track the journey of plastic waste in the ocean. This approach follows the Lagrangian method - observing the movement of objects drifting with water currents - a technique usually applied only in large-scale international studies. In addition, the team developed actual flow maps from on-site measurements and combined them with ocean current simulation models based on international meteorological data. While in Northern European countries or the Baltic Sea each method has been applied separately, for the first time in Vietnam both methods have been fully integrated to simulate the seasonal and estuarine drift pathways of marine plastic waste. This approach not only enhances the accuracy of results but also opens the possibility for direct application in forecasting and managing coastal plastic pollution in Vietnam.
The data collection sites were strategically arranged to ensure representativeness of the study area and suitability for field conditions. Monitoring stations were placed at key locations in Nha Trang Bay, including the Cai River estuary, the Tac River estuary, and open sea areas directly influenced by the monsoon regime.
Survey site map
Based on field surveys, collection, and analysis, the findings revealed that MPD pollution is present at high density, with particularly severe levels at hotspots such as Phan Ri port, Chi Cong beach (Binh Thuan, now Lam Dong), Phan Thiet, Sa Ky, and My A. Nearly 90% of the surveyed sites detected MPD, with 45% heavily polluted, 33% lightly polluted, and only 9% assessed as relatively clean.
Sharing on the field implementation process, MSc. Nguyen Duc Thinh noted: Initially, the team used Nomad buoys produced by SouthTeck (Spain), equipped with SPOT satellite positioning devices and data transmission via GSM/GPRS mobile networks. However, after two survey rounds, this type of buoy revealed limitations, such as frequent signal loss in offshore areas, which led to device loss and relatively high replacement costs. Subsequently, the team received sponsorship from the Korea Institute of Ocean Science and Technology (KIOST) with five Yotta Nano buoys using satellite communication, which helped reduce connection failures. Nevertheless, due to the still-high cost (around USD 1,200 per device), the team was unable to scale up deployment.
To address cost concerns and adapt to Vietnam’s conditions, the team collaborated with Dr. Vu Duy Vinh (Institute of Energy and Environmental Science and Technology - Vietnam Academy of Science and Technology), under the guidance of Prof. Dr. Alexei Sentchev (Institut de Recherche pour le Développement - IRD, France), to develop their own devices. They used PVC pipes as buoy bodies and installed GPS Trace positioning devices imported from France. Each self-made buoy cost approximately USD 80 while still ensuring accurate tracking of plastic waste trajectories in the field.
A novel feature of the project is the development and application of a coupled hydrodynamic modeling system, based on the open-source OpenDrift platform and the Delft3D model (a 2D/3D hydrodynamic modeling suite for simulating ocean currents), to simulate and forecast the transport and accumulation of plastic waste in the South Central coastal waters of Vietnam. Specifically, the research team integrated multiple types of input data, including: wind data from the ERA5 reanalysis meteorological dataset of the European Centre for Medium-Range Weather Forecasts, ocean currents from the Delft3D model, and in situ measurements from the drifter system. After calibration and validation, the model demonstrated high accuracy in reproducing the drift direction, speed, and accumulation zones of MPD under varying seasonal meteorological and oceanographic conditions (Northeast and Southwest monsoons).
The simulation process identified high-risk accumulation zones for plastic waste, including Nha Phu Lagoon, Bai Dai, Nha Trang Beach, Cam Ranh, and Hon Tre - coastal areas already under significant pressure from tourism and urbanization. Notably, the model has been packaged into a stand-alone, user-friendly program named VAST-PlasticDrift. With VAST-PlasticDrift, users only need to input the emission location and desired timeframe to quickly simulate the drift trajectory of plastic waste. This tool thereby provides timely support for seasonal collection, emergency responses to waste spills, effective coastal zone management planning, community education, and proactive marine environmental policy-making.
User interface of VAST-PlasticDrift
The research achievements have been published in prestigious domestic and international scientific journals, affirming their practical value in simulating, monitoring, and forecasting the drift of marine plastic waste. Notably, two high-quality international articles were published in Ocean Science, an SCI-Q1 journal (IF: 5.9). These studies focused on describing the characteristics of surface currents in the South Central coastal waters of Vietnam using high-frequency radar data combined with numerical modeling, providing insights into the mechanisms of plastic waste transport and accumulation in the region. Furthermore, the research clarified the role of currents, tides, and rivers in shaping upwelling phenomena off southern Vietnam - an important factor influencing the dispersion or accumulation of marine plastic waste.
Sharing on future directions, the research team noted: The Lagrangian field sampling method has been and will continue to be applied in large-scale oceanographic surveys, such as the ANTEA research vessel expedition within the framework of the project “Research on the transport of terrestrial material (river plume) and its impacts on the environment and coastal ecosystems of Vietnam.” Beyond plastic waste, the team plans to expand their research scope to other types of materials, in order to better understand the interactions between natural processes and human impacts on coastal marine environments. This will provide a solid scientific foundation for Vietnam’s future strategies on the sustainable development of marine ecosystems.
Selected fieldwork images of the research team
Translated by Phuong Ha
Link to Vietnamese version
