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Hidden Flows

What are hidden flows?

Hidden flows are resources associated with material extraction, and in this study are excluded from the resource flow analysis, as they do not enter the economy. An example of a hidden flow would be the large quantities of materials disturbed during quarrying. Hidden flows have been identified and quantified here as they have environmental impacts associated with them, and may be important when considering resource management in the South West.

Main source of data

  • The Wuppertal Institute's TMR study Total Material Resource Flows of the United Kingdom (Bringezu & Shutz, 2001).

Data availability and quality

Hidden flow data was limited. Bringezu & Shutz's 2001 TMR study was the most complete study available, yet data quality varied. Coefficients were available for 16 different materials produced and 25 materials imported and exported. The coefficients were based on averages for the world or other nations. These coefficients were applied to the South West, in the absence of UK- or South West-specific data on hidden flows. As a result, the results should be used with caution. The geographical and geological makeup of a nation influence mineral extraction, and hidden flow coefficients vary significantly between countries due to different mining and quarrying techniques. For example, these are the hidden flow coefficients of imported hard coal from four major producing countries:

  • Australia – 10.64 tonnes of hidden flows per tonne of hard coal.
  • Russia – 5.13 tonnes per tonne.
  • Canada – 18.87 tonnes per tonne.
  • South Africa – 3.84 tonnes per tonne.

In such cases averages were used, except where available information suggested that UK imports or exports were predominantly from one country or group of countries.

Calculation and proxy measures used

Proxying was not necessary as material production, imports and exports had already been calculated (see Materials section). Wherever possible, Bringezu & Shutz's hidden flow coefficients were applied to the corresponding materials data to quantify hidden flows. This was done for production, imports and exports although a total hidden flow figure could not be estimated due to significant data gaps.

Data recommendations

  • More research needs to be carried out on hidden flows, particularly in the UK, similar to studies such as the Industrial Ecology of the Metal Sector: Metal Material Flows in Finland (Juutinen & Viitanen, 2000) which managed to calculate hidden flows associated with household goods.