Hydrogeological research: Beginning of the end or end of the beginning?

This paper uses citation data to assess whether articles published in key g round water journals such as Ground Water (GW) and Water Resources Research (WRR) are impacting research. Citation information was obtained from SCI J ournal Citation Reports and The Web of Science - databases maintained by th e Institute for Scientific Information (ISI), Information extracted from Th e Web of Science was processed further to remove corrections to papers, dis cussion/replies, and book reviews. Generally, there are many ground water p apers published, but citations of these papers are limited. Approximately 1 0% to 15% of WRR articles, and 2% to 3% of GW articles attract more than 50 citations in their lifetimes. In both GW and WRR, the top 10% of papers ev entually will contribute nearly half of the total yearly citations. Another emerging trend is a diminishing emphasis on citations to new work as compa red to work more than 10 years in age. When articles in Ground Water or Jou rnal of Hydrology cite papers in Water Resources Research, those papers cit e work 10 or more years old half of the time. If one believes that citation s are a measure of science impact, then there is cause for concern. Researc h is inefficient with much produced for little gain. On a typical industria l life-cycle curve, ground water research is likely ranked as mature and cl ose to aging. At this stage, much work will have been completed and the num ber of truly impactful problems will have dwindled to just a few.