The transport via watercourses of material, energy, and/or organisms. Hydrological connectivity refers to the passage of water from one part of the landscape to another, and is expected to generate some response in the catchment runoff (Bracken and Croke (2007) Hydrol. Process. 21, 1749). See Gooseff (2011) Geog. Compass, DOI: 10.1111/j.1749-8198.2011.00445.x, for a worked example.