Stronger weighting of different flow times of different protection zones enables more differentiated risk assessment
RiskPlus UpDate: Optimised protective effect assessment
Stronger weighting of different flow times of different protection zones enables more differentiated risk assessment
We have optimised the assessment of the protective effect of groundwater catchment areas in RiskPlus in order to take greater account of the different flow times in the various protection zones and to further differentiate the risk assessment.
Two components of the protective effect assessment
The assessment of the protective effect of groundwater catchment areas in RiskPlus is based on two components:
• Vertical protective effect of the groundwater cover based on analyses by the Federal Institute for Geosciences and Natural Resources and various state geological offices.
• Horizontal protective effect by the flow path in the aquifer based on the permeability of the utilised aquifer and the water protection zone.
The assessment and weighting are not physically based, as the data basis does not permit such an approach. Rather, the aim is to prioritise the risks based on a relative comparison of flow times. The longer the flow time, the more extensive the degradation, retention and dilution of hazards. The assessment of the horizontal protective effect has now been adapted for some permeability classes in order to optimise prioritisation. The assessment of the protective effect now takes greater account of the location in the protection zones and better reflects the protection provided by the longer flow time.
More precise risk categorisation for a better basis for decision-making
By adjusting the assessment for certain permeability classes, the protective effect within the protection zones is now taken into account in a more differentiated manner. This leads to a more accurate depiction of protection through longer flow times.
In some cases, optimisation has a direct impact on the assessment of the risk to the raw water:
• In protection zones I and II, the assessment remains unchanged.
• In protection zone III (incl. III A / B / C) and in the catchment area outside the protection zone, some risks for raw water now fall into a lower risk class.
These changes were implemented for both newly created and existing catchment areas to ensure a consistent and transparent assessment.
With this further development, RiskPlus offers an even more precise decision-making basis for risk assessment in the drinking water supply.
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