BiKi Hydra is a tool aimed at assessing the persistence of water molecules inside a specific site. This persistence based ranking can be obtained by imposing a properly tuned electrostatic-like repulsion between the site/ligand and the surrounding water molecules. The most persisting water molecules are those that upon repulsion are able to maintain their original positions.
S.R. Zia et al., Probing Hydration Patterns in Class-A GPCRs via Biased MD: The A2A Receptor. J. Chem. Theory Comput.