• Andreas Bruun Olesen
  • Heidi Kleis Gautesen
This project report is focussed on the possibility of implementing forecast based groundwater abstraction. The idea is that forecast based groundwater abstraction should be a tool for the municipalities to be better at fulfilling requirements in the Water Framework Directive. This directive prescribes that groundwater abstraction should not influence the body of groundwater to an extent that negatively affect the ecological status of streams and other nearby ecosystems. This report provides a method for the water supply to assess where water abstraction will have the smallest environmental impact, adjusting the groundwater abstraction accordingly. This also means that the water supply is able to abstract more groundwater in periods where streams and other wet ecosystems are not threatened.

In the preliminary analysis, different streams in and near Aalborg municipality is characterized, and groundwater potential data from Aalborg and Rebild municipality is extracted. The data is then sorted and the data which accommodates stated quality criteria can be used further on in the analysis.
In the main analysis, a correlation analysis is to illuminate the connection between groundwater potential from separate months and the yearly minimum flows in streams. The analysis shows some unexpected tendencies, which is further analysed. It is concluded that the yearly variation in groundwater potential have equal impact on the yearly minimum flow, than the groundwater recharge in the spring alone.

This knowledge provides the basis of making a prediction model, which is able to predict the yearly minimum flow based on groundwater potential. A validation shows that the model is fairly precise. To illuminate if a new method, described in the second management cycle of the Water Framework Directive, for calculation of the ecological status of streams can also be covered by a prediction model, this method is also analysed. It is concluded based on this analysis that this method is associated with great uncertainties, and therefore cannot be covered by a prediction model.

A Mike SHE model is used to figure out exactly how much time it takes before a groundwater abstraction is adjusted, and to this adjustment can be observed in the stream. This information is used to fit simple models, which is able to describe the influence from an adjusted groundwater abstraction on the covered streams.

At last some different scenarios is calculated with the purpose of demonstrating the potential of forecast based groundwater abstraction. It is proven that some years allow for an increased groundwater abstraction, while others don't. In total this concept allows for a considerable increase in groundwater abstraction, without influencing the ecological status of streams, estimated by median minimum flow.
Publication date1 Jun 2016
Number of pages135
ID: 234492592