  We study the impact of the Gradient Flow on the topology in various models of
lattice field theory. The topological susceptibility $\chi_{\rm t}$ is measured
directly, and by the slab method, which is based on the topological content of
sub-volumes ("slabs") and estimates $\chi_{\rm t}$ even when the system remains
trapped in a fixed topological sector. The results obtained by both methods are
essentially consistent, but the impact of the Gradient Flow on the
characteristic quantity of the slab method seems to be different in 2-flavour
QCD and in the 2d O(3) model. In the latter model, we further address the
question whether or not the Gradient Flow leads to a finite continuum limit of
the topological susceptibility (rescaled by the correlation length squared,
$\xi^{2}$). This ongoing study is based on direct measurements of $\chi_{\rm
t}$ in $L \times L$ lattices, at $L/\xi \simeq 6$.
