Detail Data have been working with Keep Northern Ireland Beautiful to make use of their data.
Since 2012 Keep Northern Ireland Beautiful have run a Marine Litter programme, collecting information about rubbish found on beaches around Northern Ireland.
Four times a year, KNIB volunteers count the different types of litter on a number of Northern Ireland beaches. 2,500 volunteers from local communities, schools and businsses also clean up the litter afterwards, helping to lift over 4,000kg since 2012.
The surveyors count litter over two distances. One, a comprehensive 100 metre line (usually around 20 metres in width), for which they could each type of litter no matter how small. Second, a longer 1km, where only larger items (50cm and bigger) are included.
The more comprehensive survey allows an estimate of how much litter there is to be found, on average, for every 100m of these beaches on the coastline of Northern Ireland.
Keep Northern Ireland Beautiful typically produce an annual report that details their findings. For the 2016 report, we worked with KNIB to produce an interactive dashboard covering all of the past surveys (back to 2012).
This required a bit of work to get the data into a consisitent and suitable format for use in visualisation software. We used Open Refine to help with this cleaning process, and Tableau Public to build the above visualisations.
The benefit to this is that it makes analysing the data more straightforward. For example, in 2016 it was decided to concentrate surveying on a smaller number of beaches. Therefore, any analysis (such as average numbers of litter) would need to be across the same beaches for the whole time span of the survey. The dashboard makes this easy to do, filtering beaches and seasons to make comparisons easier.
For all of the surveys that have been carried out across ten beaches, there have been an average of 528 items found per 100 meters. The amount and type of litter will vary for each beach and season. The 2014 storms are probably the reason behind the large amount of litter seen for the winter survey (around 1,200 items per 100m).
Certain beaches regularly see more litter than others. Ballyhornan, for example, often has the largest amount of litter of the beaches for any season. As the majority of marine litter comes from the sea, tidal patterns and flows have a large part to play in how much litter ends up on the shoreline.
The visualisation also allows viewers to see what types of litter are found, as this is the level of detail that is recorded in the surveys.
The large majority are types of plastic, of which there are large and small pieces, fishing rope, string and cord, sweet wrappers, drinks bottles, caps and lids. Among sanitary items, cotton bud sticks present a problem as the plastic type persists and doesn't degrade (there is a campaign urging people to only buy paper-based cotton buds). The bubble chart below shows how these different categories make up the litter found during the NI Marine Litter Surveys.
You can read more in depth about marine litter in Northern Ireland in the 2016 report on the KNIB website.
As well as using the data for the visualisation, Keep Northern Ireland Beautiful have published the datasets for each of the surveys on our portal. You can find them all here.