The term 'connectivity' is increasingly being applied in hydrological and geomorphological studies. Relevant research encompasses aspects of landscape connectivity, hydrological connectivity and sedimentological connectivity. Unlike other disciplines, notably ecology, published studies show no consensus on a standard definition. This paper provides an overview of how existing research relates to the concept of connectivity in both ecology and hydrology by proposing and evaluating a conceptual model of hydrological connectivity that includes five major components: climate; hillslope runoff potential; landscape position; delivery pathway and lateral connectivity. We also evaluate a proposed measure of connectivity called the volume to breakthrough to quantify changing connectivity between different environments and catchments.