Marine litter is a serious problem for the coastal and marine environment, and there is now a myriad of projects tackling this problem using geospatial technology, i.e., digital tools for the geographic mapping and analysis of the Earth and human societies, including remote sensing, global positioning system (GPS), and geographic information systems (GIS).

Remote sensing and the GPS are methods for collecting information about Earth’s surface, while GIS is a mapping tool for organizing and analysing information.

The marine ecosystem provides a vital source of food and livelihoods for many countries, through fisheries, tourism, shipping, aquaculture, ports and energy. Marine pollution, in the form of plastics, sewage, chemicals and other by-products, poses a risk to the ecosystem, leading to potentially lasting loss of revenue for impacted countries, food insecurity, public health hazards and other negative consequences.

OpenLitterMap

Openlittermap.com is an initiative by Irish entrepreneur Seán Lynch to tackle the global litter crisis including marine litter on beaches, using geospatial data to pinpoint the location of marine litter.

In an interview with Open Source, Lynch said that “OpenLitterMap is an open source, interactive, and accessible database of the world’s litter and plastic pollution.

“Inspired by OpenStreetMap, we apply the same principles of crowdsourcing and open data to plastic pollution. We want everyone, everywhere and anywhere, to be able to share data on litter and plastic pollution on the streets, beaches, and anywhere else where plastic can be found.”

OpenLitterMap rewards users with Littercoin, a type of cryptocurrency, for doing the work of collecting, mapping, processing and producing open geospatial data on an increasing variety of pre-defined types of litter. This process is currently accomplished through a web-app.

To ensure data quality, all data goes through a manual verification process, which is being done by a small team of trained volunteers. This verified data is then used to develop machine-learning algorithms that will make manual processing and verification easier.

Marine LitterWatch

Marine Litterwatch (MLW) is an app developed by the European Environment Agency (EEA) to collect data on marine litter on beaches for the Marine Strategy Framework Directive (MSFD) to support official monitoring.

A similar concept to that of OpenLitterMap, MLW combines citizen engagement and geospatial technology to help tackle marine litter. Communities organize either clean-up or monitoring events on beaches and undertake surveys with a mobile app to report on litter location.

Beach surveys are made using a European master list of marine litter items. These items are commonly found on Europe’s beaches, for example, plastic bags and bottles, cigarette butts, fisheries related materials, etc.

Data on the litter found is submitted through the app to a central database hosted by the EEA. From this database, data can be retrieved, directly linked or used by regional and national databases to be further disseminated into a wider range of products such as survey reports and maps.

ASEAN Geospatial Challenge

In the keynote speech at Geo Connect Asia 2022, Singapore’s Second Minister for Law Edwin Tong mentioned the ASEAN Geospatial Challenge, where students leverage on geospatial technology and information to address the United Nations’ Sustainable Development Goals.

Tong cited an example in which geospatial technology was leveraged to solve the marine litter problem. “One of the winning entries uses remote sensing and geospatial mapping to identify locations where marine debris collects, so that we can recycle the waste into everyday products.”

Cleaning up the Mekong

The Mekong River is thought to be one of the most polluted rivers in the world.  The government of Cambodia in collaboration with the World Bank, has launched a project to tackle this problem. There is a need for a better understanding on what the current situation is in terms of plastic and waste hotspots along rivers and beaches, as well as an overview of what type of plastic and waste is present in the freshwater system.

Therefore, drones and artificial intelligence are used to map, quantify and identify waste in rivers and coastal areas in Cambodia.  This method uses high geospatial resolution imagery captured by drones to quickly collect data from large areas in a short time.  Two machine learning components will then process the captured images and allow for plastic litter detection, plastic litter quantification and water type classification.

Other geospatial tools in fight against marine litter

According to the Marine Litter White Paper published by Geo Blue Planet, other data collection tools include ship-based cameras, high altitude pseudo satellites, and remotely piloted aircraft systems, which can collect visual imagery to aid in the analysis of beach litter as well a sea surface litter.

Photographing marine litter using a camera fixed to the bow or mast of a vessel is an emerging approach for monitoring floating marine litter. High-resolution cameras or other sensors mounted on ships can increase the observations on the floating litter and with the use of AI, provide in situ observation in real time.

Remotely operated vehicles (ROVs) such as submarines or manned submarines, can view seabed litter plastic or take core or surface samples to detect presence of microplastics and other litter. ROVs are often preferable for litter surveys on continental slopes, uneven terrain, or the deep seafloor.

Synthetic Aperture Radar (SAR) provides high-resolution image of the radar reflectivity of an observed scene. SAR has the potential to provide information about expected locations of marine litter and detect mega-litter on the water’s surface but is sensitive to parameters such as surface roughness.

Satellite remote sensing of beach litter and sea surface litter is currently in the research and development phase, primarily repurposing missions that were not originally designed for litter monitoring. Satellite imagery relevant for remote sensing of beach litter includes visual imagery and spectral analysis.

Lynch, the founder of OpenLitterMap, said that “for most people, litter has become normal and invisible. It has blended into the backgrounds of our lives. But global pollution should not be normal, and it is far from acceptable.”

There is an urgent need for regular and standardized monitoring of marine litter in order to understand long-term changes in marine litter and for the successful development and implementation of mitigation strategies. The diverse nature, sources and impacts of marine litter require a wide range of geospatial technologies to combat it.

Photo credit: iStock/3dsam79