To investigate statistical problem of moderate to low-frequency sound scattering on the two-dimensional (2D) random inhomogeneities of a shallow sea with horizontal boundaries (bottom and surface) and loss local-mode approach has been utilized. An explicit-form solution by quadrature for modal amplitudes as a function of distance is represented. In adiabatic approximation asymptotical estimations have been performed, which demonstrate how medium weak fluctuations influence the local eigenvalues and statistical characteristics of a field. It is shown that general effects previously established while studying the random layered problem keep the force. Spatial scales of statistical influence and laws of dependences are determined. Also it follows from the analysis of the explicit-form solution for modal amplitudes that in this shallow-sea model with horizontal boundaries and in the absence of regular variations of sound speed the coupling of modes is insignificant. General statistical effects are described well within the framework of adiabatic approximation.

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