A Conceptual Flow Model (CFM) is a description of sources and flow paths for groundwater flow through an aquifer from points of recharge to points of discharge. It may be a qualitative description with as much quantification as possible based on the descriptions.
(Sources: Anderson MP, and W Woessner (1992). Applied Groundwater Modeling: Simulation of Flow and Advective Transport. Academic Press; Fetter CW (2001). Applied Hydrogeology, 4th Edition. Prentice-Hall; and Myers T (2013). Remediation scenarios for selenium contamination, Blackfoot watershed, southeast Idaho, USA, Hydrogeology Journal, DOI 10.1007/s10040-013-0953-8)