The formation of a steady quasi-geostrophic flow component over undulating bottom variations is analysed in the case when wave-topography interactions dominate over nonlinear wave-wave couplings. A low-order model is proposed to describe quasi-linear dynamics and our main attention focusses on the qualitative structures of two functions: the correlation between relative vorticity and topography (C) and a topographic stress force (D).Cturns out to be both positive and negative depending on the parameters of an incident wave and topography mode, and on the dissipation mechanism taken into account. The β-effect increasesCand isotropy of the dynamical wavy field or that of the topography decreases this quantity.