Non-agricultural pollution to rivers in Scotland

Non-agricultural pollutant emissions were calculated for each WFD waterbody on the basis of tabulated discharges and empirical models. Losses from septic tanks were derived from SEPA licensing records and per capita coefficients, whilst losses from sewage treatment works were derived from consented dry weather flows and average concentrations from compliance monitoring. Losses from urban areas were calculated using the Event Mean Concentration model of [1] whilst montane and woodland losses were calculated using the PLUS and MARS models ([2] and [3] respectively). Losses from bank erosion were calculated using a simple index of bank erosion that was calibrated against available sediment tracing data.

[1] Mitchell, G. Lockyer, J. and McDonald, A.T. (2001) Pollution hazard from urban nonpoint sources: a GIS-model to support strategic environmental planning in the UK. Technical Report, School of Geography, University of Leeds, UK.

[2] Donnelly, D., Booth, P., Ferrier, R. and Futter, M. 2011. Phosphorus Land Use and Slope (PLUS+) Model. User Guide and Computer Code. Report to SEPA, Scotland, UK. 39 pp. Availalble from http://www.hutton.ac.uk/sites/default/files/files/Plus+%20User%20Guide%20-%20v1_6.pdf

[3] Hughes, G., Lord, E., Wilson, L., Gooday, R. and Anthony, S. (2008) Updating previous estimates of the load and source apportionment of nitrogen to waters in the United Kingdom. Defra project WQ0111, final Report, 112 pp.