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SCIMAP is an approach to the generation of risk maps for diffuse pollution within catchments. SCIMAP aims to determine where within a catchment is the most probable source of diffuse pollution and is based on a probabilistic / relative approach.

Diffuse Pollution

Diffuse pollution is a major management challenge as it commonly involves processes that are: small in magnitude; distributed over a large spatial scale; and are associated with particular types of land use activity when they are also well connected to the drainage network.

The SCIMAP project is developing a framework for the analysis of the relative risk of different locations within the catchment (in relation to their land use, land management etc.) in relation to different environmental requirements within receiving water bodies (e.g. fish habitat). The basis of the analysis is the joint consideration of the probability of a unit of land producing a particular environmental risk and then of that produced risk actually reaching the drainage network. Hydrologically well-connected and risky land uses should be the prime focus of management activities, and hence the result is a method for determining where efforts should be concentrated in order to achieve environmental protection.

1. Risk in the landscape

SCIMAP works by combining a map of the relative risk of generating diffuse pollution for 5 m by 5 m locations in the landscape. It works out the relative risk of each location in the landscape being connected to a river, lake or groundwater.

2. Does a risk get into the water environment?

By combining the risk of pollution generation and the risk of connection we can determine the risk that pollution gets into the water environment.

3. Moving the risk through the river

In the final stage, we route the connected risk across the landscape, accumulating it along flow paths. If we want, we can dilute the accumulated risk by the uplsope contributing runoff to get a risk concentration.

4. What do we now know?

The maps allow us to compare locations to see which are most likely to be problem locations, and hence where we should prioritise restoration, such as catchment sensitive farming.