One of the most cited definitions of interdependency is the one by Rinaldi et al. who define interedependency as a bidirectional relationship between two infrastructures through which the state of each infrastructure influences or is correlated to the state of the other . This definition is adopted on the Commission's staff working document on a new approach to the EPCIP . Interdependencies can be identified "between critical infrastructures, industry, and state actors". The working document also highlights that threats to a single Critical Infrastructure can have "a very significant impact on a broad range of actors in different infrastructures and more widely". The document also highlight the cross-border effect of interdependencies, spanning a number of European countries. The example identified in the document is the European high-voltage electricity grid, composed of the interconnected national high-voltage electricity grids.
Mutually reliant relationship between entities (objects, individuals, or groups) . The degree of interdependency does not need to be equal in both directions. For example, the Energy Sector depends on a functioning Water Sector for successful day-to-day operations, just as the Water Sector needs energy to effectively manage water and wastewater systems .
- Steven M. Rinaldi, James P. Peerenboom, Terrence K. Kelly, Identifying, Understanding and Analysing Critical Infrastructure Interdependencies, IEEE Control Systems Magazine, December 2001, p.14.
- Staff Working Document on a new approach to the European Programme for Critical Infrastructure Protection - Making European Critical Infrastructures more secure, SWD(2013) 318 final, Brussels, 28.8.2013
- DHS Risk Lexicon 2010 Edition, September 2010
- Critical Infrastructure Protection and Resilience Toolkit (Glossary), US Department of Homeland Security
- Unpublished working glossary of UP KRITIS and BSI, 2014