Predicting future nitrate concentrations at groundwater assets abstraction from the Chalk aquifer

Nitrate Modelling in Chalk Aquifers

To support the development of long-term and cost-effective strategies to manage concentrations of nitrate in water derived from the Chalk aquifer, Thames Water commissioned Stantec to simulate future trends in concentration at 23 of their groundwater abstraction sites.  Given the influence of seasonality in nitrate concentration within the Chalk aquifer, our internally developed model was adapted to include the increased complexity introduced by the requirement to determine seasonal fluctuations in the future trend, allowing a more accurate representation of future peak levels of nitrate in the groundwater.

As part of the project, our team conducted spatial modelling to determine groundwater catchments and the spatial contribution to source yield, which, coupled with nitrate loading data, provided information of the contributing areas of nitrate to each abstraction for input to our trending model. 

The outputs delivered from this project provided Thames Water with a method for prioritising further investigations and proposed management at these sources. It also gave the Environment Agency confidence that the measures were appropriate for consideration in future management strategies.  In addition, our team provided training, including a user manual, to enable Thames Water staff to apply the tool to further the assessments undertaken. 

We have since carried out similar nitrate trending work for four other water companies and our trending tool has been used on over 100 sources.