  For understanding the nature of gaseous flows in star-forming regions of
nearby galaxies it is usually utilized the relation between surface brightness
in H$\alpha$ line and velocity dispersion of ionized gas known as ''surface
brightness -- velocity dispersion diagram''. Using the three-dimensional
gasdynamic simulations we consider the evolution of the synthetic diagrams for
supershells driven by multiple supernova explosions in stellar cluster located
in the galactic disk. We investigate the shape and structure of the diagrams
depending on gaseous density and metallicity, disk scale height values. We show
that there are several loci of values typical for young bubbles evolved in
dense or rarefied gas at large heights above the disk midplane. We find that
the structure of the diagram is depended on age of a supershell and physical
conditions of a gas in the disk. We argue that the diagrams obtained for the
nearby dwarf galaxies can be interpreted by only using the dynamics of bubbles
driven by multiple supernova explosions in low-mass stellar clusters of
different age.
