  A scalar potential obtained from the $D$-term in the Supergravity models,
which dominates over $F$ term and is mainly responsible for the inflationary
phase in the early universe, is studied. The potential with canonical kinetic
terms for scalar fields in the Lagrangian, has a very slow roll feature in
comparison to various other plateau type inflationary potentials. In this case,
a much lower tensor-to-scalar ratio ($r$) of $\mathcal{O}(10^{-3})$ is
achievable. The requirement of slow roll condition for the inflation potential
implies that the up type neutral scalar and the down type neutral scalar in
Supergravity models are with equal field strength at the time of inflation. If
this relationship holds down to the electroweak scale for the corresponding
$vev$ values of these fields, then it will indicate a higher SUSY breaking
scale around 100 TeV. The predicted values of the inflationary observables are
well within the 1-$\sigma$ bounds of the recent constraints from {\it
Planck'18} observations. The era of reheating after the inflationary phase, is
also studied and the bounds on the reheating temperature ($T_{re}$) is
calculated for a different equation of states during reheating ($w_{re}$) for
the {\it Planck'18} allowed values of the scalar spectral index ($n_s$). For
our model with $w_{re}=2/3$ and $w_{re}=1$, after satisfying all the bounds due
to gravitino overproduction, we can have big parameter space for $T_{re}$ which
is well inside {\it Planck'18} 1-$\sigma$ bound on $n_s$.
