Sustained low flow in a river during dry or fair weather conditions, but not necessarily all contributed by groundwater; includes contributions from interflow and groundwater discharge.
Stormflow and baseflow are non-process related terms to signify high amplitude low frequency flow in a river during and immediately after a precipitation event and low amplitude high frequency flow in a river during dry or fair weather periods. Baseflow is not a measure of the volume of groundwater discharged into a river or wetland, but it is recognised that groundwater makes a contribution to the baseflow component of river flow. The term groundwater contribution to baseflow should be used.
Baseflow is an important component of the hydrological cycle.
Source: http:\\www.ust.smoothstone.com/groundwater_intro