Interactive comment on “Regional analysis of groundwater nitrate concentrations and trends in Denmark in regard to agricultural influence” by B. Hansen et al

The paper is significant because it addresses an issue very important for society, nitrate in groundwater, as well as it presents and explains methodological approaches to cope with the complexity of this issue in the context of managing it on the macro-level. It is a challenge for research to determine the relationship between policy measures taken to reduce nitrate concentrations in groundwater and their impact. The authors do not propose a methodology to assess this whole relationship but they show an important step on the way that leads to corroborating assumptions on the effects of policies. It is important that such methodologies are discussed and shared. They also present