स्थायी अथवा अध्यासीन भौमजल के बहिप्रवाह तथा बड़ी झीलों आदि की निकासी के परिणामस्वरूप सरिता के अविरत अथवा शुष्क मौसम प्रवाह को आधारभूत प्रवाह कहते है। प्रत्यक्ष अपवाह के अतिरिक्त हिमनदी, हिम तथा अन्य सभी संभावित स्त्रोतों से प्राप्त जल प्रवाह को भी आधारभूत प्रवाह कहते है।
The sustained or dry weather flow of streams resulting from the outflow of permanent or perched ground water and from the draining of large lakes and swamps. Also, water from glaciers, snow and all other possible sources not resulting from direct runoff.
Base Flow - the part of stream flow that is attributable to long-term discharge of groundwater to the stream. This part of stream flow is not attributable to short-term surface runoff, precipitation, or snow melt events.
Baseflow - The sustained or fair weather flow in a channel due to subsurface runoff. In most streams, baseflow is composed largely of groundwater effluent. Also known as base runoff.
Base flow: The part of the discharge, which enters a stream channel from groundwater. This is the runoff observed during long periods when no precipitation or snowmelt occurs.