ABSTRACT Groundwater makes an important contribution to public water supplies, yet the dynamics of groundwater availability are often simplified in large‐scale water resource assessments. This study addresses that challenge on a national scale in England by integrating an empirically based groundwater supply model with a national‐scale water resource system simulation model. Through comparison of dynamic and steady groundwater representation and the use of a large‐ensemble climate dataset, we illustrate the contribution of groundwater to system supply and performance at a national scale and highlight regional differences in response. The south‐east showed particular sensitivity to groundwater flow: In the far‐future scenario, the median number of days with restrictions increased by 40% following the introduction of our dynamic groundwater model, compared to simulations based on licensed groundwater yields. Our results emphasise the importance of dynamic representation of groundwater supplies in large‐scale water resource assessments.
Pugh et al. (Fri,) studied this question.