In processing of sonar data, beamforming process plays a central role in reducing the effects of the surface and bottom reverberation. In shallow water environments where the reverberation is dominant, target detection from the beamformed results is not effective and may lead to significantly high false alarm rate. This paper presents a novel approach for postprocessing sonar beamformed imagery in order to improve the detectability of the targets while substantially reducing the occurrence of the false detection. This is done using the recursive high order correlation (RHOC) method which exploits the spatial-temporal correlation between consecutive pings of the beamformed images. Test results on several sets of sonar data show the great efficiency and power of the proposed method especially in very high cluttered environments.