  We show that the recently introduced two-field flux-balanced
Hasegawa-Wakatani (BHW) model captures the key features of drift-wave turbulent
transport mediated by zonal flows observed in more complete and accurate
gyrokinetic simulations, such as the existence of a nonlinear upshift of the
threshold for drift wave turbulence driven transport, often called the Dimits
shift, as well as non-local transport with avalanche bursts and solitary
propagating structures. Because of the approximations made in the BHW model,
these observations are made for the particle flux instead of the heat flux more
commonly studied in ion temperature gradient (ITG) driven turbulence in fluid
or gyrokinetic codes. Many of these features are not seen in other
Hasegawa-Wakatani models, which confirms the critical role of the electron
dynamics parallel to the magnetic field lines. To address questions regarding
the role of boundary conditions on the drift-wave zonal flow dynamics, we apply
our model to both a channel domain geometry and the more typical doubly
periodic geometry. We only observe strong soliton-like solutions in the
particle flux for the channel geometry, in the vicinity of the boundaries,
where strong velocity shear and density gradients are generated which are
absent in the doubly periodic simulations. Changing the aspect ratio of the
simulation domain also has a significant effect. In domains which are elongated
in the radial direction, more complex multiscale dynamics takes place, with
multiple zonal jets interacting with each other, and large scale avalanches.
