<p>The sensitivity of fluvial fill terraces to tectonic and climatic boundary conditions make them potentially useful archives of past climatic and tectonic conditions. However, we currently lack a systematic understanding of the impacts of base-level, water discharge, and sediment discharge changes on terrace formation and associated sediment storage and release. This knowledge gap precludes a quantitative inversion of past environmental changes from terraces. Here we use a set of seven physical experiments to explore terrace formation and sediment export from a braided channel system that is perturbed by changes in upstream water discharge and sediment supply, or downstream base-level fall. Each perturbation differently affects (1) the geometry of terraces and channels, (2) the timing of terrace formation, and (3) the transient response of sediment discharge. In general, an increase in water discharge leads to near-instantaneous channel incision across the entire fluvial system and consequent local terrace cutting, preservation of the initial channel profile on terrace surfaces, and a transient increase in sediment export from the system that eventually returns to its pre-perturbation rate. In contrast, changes in the upstream sediment supply rate may result in longer lag-times before terrace cutting, leading to a less well-preserved pre-perturbation channel profile, and may also produce a gradual change in sediment output towards a new steady-state value. Finally, downstream base-level fall triggers the upstream migration of a knickzone, forming terraces with upstream-decreasing ages. The gradient of terraces triggered by base-level fall mimicks that of the newly-adjusted active channel, whereas gradients of terraces triggered by variability in upstream sediment or water discharge are steeper compared to the new equilibrium channel. Our findings provide guidelines for distinguishing between different types of perturbations when interpreting fill terraces and sediment export from fluvial systems.</p>