In this contribution a discussion is presented on the development of self-organized coastal morphodynamic patternswhich are due to the joint action of gradients in the depth-integrated concentration and the flow. This is done in thecontext of a depth-averaged shallow water model. Two physical mechanisms produce deposition-erosion patterns.Deposition either occurs where the current flows from high to low depth-averaged concentrations (1) or where the flowdiverges (2). If flow conditions are quasi steady (i.e., the time scale on which bedforms evolve is much larger than thehydrodynamic time scales) only the former mechanism contributes to the formation of bottom patterns.