Impact pathways upon human well-being of emissions to water


The Industrial Emissions Directive (IED) of the European Union requires the adoption of ‘Best Available Technology’ (BAT). This can however be mitigated by producers obtaining a derogation (exemption) from a full rigour of the relevant emission standard under certain circumstances.

Natural Resources Wales (NRW), Environment Agency (EA), and Scottish Environment Protection Agency (SEPA) are working collaboratively to update the Life Cycle Assessment approach underlying the IED and BAT, particularly the qualitative and quantitative methodologies underpinning derogations.

We were appointed to:

  1. Describe the impact pathways of common point source and diffuse pollutants entering water bodies which affect human well-being through degradation of ecosystem services
  2. Consider the applicability of water quality models to adopt as BAT under the IED.


A literature review was conducted to investigate point one above. The suitability of Source Apportionment-GIS (SAGIS) as a tool within impact pathway analysis was then assessed. A systems-based framework was designed to enhance understanding of the impact of pathways upon human well-being.

SAGIS-SIMCAT modelling was used to simplify the representation of physical and chemical processes of pollutant mobilisation and fate in receiving waters. An Integrated Catchment (INCA) model was also utilised to produce dynamic model representations of:

  • Plant and soil system dynamics
  • Instream biogeochemical and hydrological dynamics.

These can assess the effects of multiple sources on water quality and aquatic ecology, whilst minimising data requirements and model structural complexity.


The systems-based framework provides an assessment of the suitability of SIMCAT/SAGIS. It provides a better understanding of the multiple benefits or disadvantages of the impact of emission pathways on water and its ecosystem services.

Consequently, the impact on human well-being can be better understood in ecosystem services and therefore is represented in natural capital accounting, or a cost-benefit methodology.

Recommendations were made to improve screening requirements. Additional contaminant modelling was proposed to provide a more comprehensive contaminant assessment, which can subsequently be used to mitigate against impacts on human well-being.

Want to know more?

Email Rachelle Ngai for more information regarding our skills and experience in this area. You can also find out more on our environmental web pages.

Find out more about our natural capital work in our Knowledge Hub.

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