  In this paper we mainly describe $\mathbb{Q}$-Gorenstein smoothings of
projective surfaces with only Wahl singularities which have birational fibers.
For instance, these degenerations appear in normal degenerations of the
projective plane, and in boundary divisors of the KSBA compactification of the
moduli space of surfaces of general type [KSB88]. We give an explicit
description of them as smooth deformations plus 3-fold birational operations,
through the flips and divisorial contractions in [HTU13]. We interpret the
continuous part (smooth deformations) as degenerations of certain curves in the
general fiber. At the end, we work out examples happening in the KSBA boundary
for invariants $K^2=1$, $p_g=0$, and $\pi_1=0$ using plane curves.
