  Colloidal gels have strong industrial relevance as they can behave liquid-
and solid-like. The latter allows them to support the buoyant weight against
gravity. However, the system is intrinsically out-of-equilibrium, which means
that the colloids must eventually settle out of the suspension. The process of
settling has been captured theoretically, but the presence of a delay time
during which the gel appears relatively unaffected by gravity has not. Here, we
modify existing frameworks to capture this delay, by treating the gel as a
continuum with viscoelastic response that is based on the local bond density.
We can solve our model numerically to obtain the evolution of the colloid
density profile and recover qualitatively the accumulation of a dense layer on
top of the settling gel, as is experimentally observed in depletion gels. This
numerical study is complemented by a theoretical analysis that allows us to
identify an emergent time and length scale that set the dynamics of the gel.
Our model provides a solid foundation for future studies that incorporate
hydrodynamic erosion and tackle industrially relevant geometries.
