Debris sources and transport from the coastal margin to the ocean

CSIRO’s marine debris researchers, co-funded by the Australia Packaging Covenant, have worked to better understand the sources of debris that end up on our shores and in our ocean. To do this, we developed a model that used meteorological, geographic and national litter data to predict how litter travels through waterways and to the ocean.

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We found that:

  • Human deposition was by far the most important in determining the load of plastics at a site
  • Transport by water was the second most important
  • A discernible, but smaller, contribution is made by wind. The research identified hotspots of coastal debris which can enable cost-effective target regions for waste reduction.
Map of debris hotspots based on all survey data from CSIRO, CUA and KAB. Note higher debris loads in urban cities around Australia’s coastline. Data are reported as the log base 10 of the total amount of debris per 1000m2.

Map of debris hotspots based on all survey data from CSIRO, CUA and KAB. Note higher debris loads in urban cities around Australia’s coastline. Data are reported as the log base 10 of the total amount of debris per 1000m2.

The research found that both socio-economic factors and the amount of time people spent at a site play a significant role in the amount of litter left behind. We also found
that the context of the site was important, for instance litter is found in national parks.

We identified a number of variables that affect litter and dumping loads, including population density and accessibility. Using the watersheds in the greater Brisbane area, as well as meteorological, geographic and national litter data, we developed a model which allows us to predict the debris load at unsurveyed sites.

The research showed that people are the greatest contributor to marine pollution meaning that to make a real difference, people must be part of the solution.

There is a significant opportunity for local governments to use this information to positively impact the resources allocated to, and the jobs undertaken by, waste management teams. We can now look at litter loads where there are no traps and compare them to sites with traps, which allows us to identify critical locations for future investments.

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