  We construct a sandpile model for evolution of the energy spectrum of the
water surface waves in finite basins. This model take into account loss of
resonant wave interactions in discrete Fourier space and restoration of these
interactions at larger nonlinearity levels. For weak forcing, the waveaction
spectrum takes a critical $\omega^{-10}$ shape where the nonlinear resonance
broadening is equal to the Fourier grid spacing. The energy cascade in this
case takes form of rare weak avalanches on the critical slope background. For
larger forcing, this regime is replaced by a continuous cascade and
Zakharov-Filonenko $\omega^{-8}$ waveaction spectrum. For intermediate forcing
levels, both scalings will be seen: $\omega^{-10}$ at small and $\omega^{-8}$
at large frequencies. The interval between these two scaling regions is
characterised by strong avalanches.
