The impact of buoyant discharge variations on the dynamics of coastal buoyancy-driven currents is studied using a primitive equation numerical model (SPEM5). First, variable discharge is introduced as harmonic fluctuations of the inflow velocity at the tidal (period 12 hours) and subinertial (period 10 days) frequencies. Tidal fluctuations produce only minor effects on the buoyant plume compared to the case of constant inflow, while subinertial fluctuations substantially modify the anticyclonic bulge. A partially detached anticyclonic plume forms when discharge subsides after reaching its peak value. Such a plume has maximum offshore extension some distance downstream of the mouth with the lightest water separated from the coast. A secondary bulge forms during the low runoff interval. When high discharge resumes, this secondary bulge is shifted offshore and enhanced for some time. An individual high-discharge event is next considered, where both the net transport of the inflow and the absolute value of its density anomaly increase and then return to their initial (background) values over 5 and 10 day time intervals. This event also generates a partially detached plume (especially with the 10 day duration). In this case, the lightest water occupies the downstream part of the bulge and is separated not only from the coast but also from the mouth. The effect of variable discharge is more dramatic with a uniform downstream current of 0.1 m s-1. Under such conditions, constant buoyant discharge does not form a well-pronounced anticyclonic bulge. In contrast, variable discharge produces an almost circular anticyclone during the high-runoff interval. As runoff decreases, this anticyclone separates from the source and either continues to propagate downstream as an individual eddy or is modified by the next cycle of increasing discharge. Observational evidence for both the partially detached bulge near the mouth and the anticyclone propagating downstream from its source is presented in this study. One feature was observed at the mouth of the Columbia River estuary; the second feature was observed off the southern New Jersey coast ~150 km south of its source, the Hudson estuary. ¿ 2001 American Geophysical Union