The Discretized Kirchhoff Integral method has been recently tested against laboratory experiments using a model with surface curvatures and sharp edges generating wave diffraction effects. Comparisons between numerical and laboratory data have exhibited a good quantitative fit in terms of time arrivals and amplitudes, except in the vicinity of secondary shadow boundaries created by the interaction of the edges of some topographical structures. Following this work, the effect of multiple scattering and the surface curvatures on the wavefield is studied here, using the so-called diffraction attenuation coefficient, in order to define the cases where these effects may be neglected in the numerical modeling without loss of accuracy.