ABSTRACT: This paper describes relations between recession coefficient a and hydraulic parameters derived from numerical model of a karst-fissure aquifer, described by: a=C.T/SA For studying discharge time-series was created by Visual MOOFLOW 20 a numerical model of karst-fissure spring Vajár (Rohožník). Heterogeneity of a karst aquifer was schematized by a high conductivity discrete karst channel in a low conductivity fractured limestone volume. By comparing recession curves of the spring Vajár, recession curves of a simulated spring and calibrated hydraulic parameters coefficient C was determined, containing inaccuracy of mathematical equations. According to the coefficient C, more important for discharges of the modelled karst-fissure spring are the high conductivity karst-channels than fractured limestone volume with low conductivity.