Conventionally, two-dimensional and depth-averaged methods have been employed to simulate the sediment deposition, transport and erosion in tsunamis and storms. The simulations of the sediment dynamics for both events has the advantage that we learn about the interaction of the respective flow and the movable bed in general, but if done with consistent methods we can also learn about the differences in sediment dynamics between tsunami and storms. The difference then becomes important to understand the different features that storm and tsunami deposits exhibit for modern deposits of both events as well as in the geologic record. Unfortunately, there seem to be no consistent difference in the characteristics of both deposits. Furthermore, our current understanding of sediment dynamics may not be sufficient to catch the differences that apparently exit between the flow dynamics during storms and tsunamis. We argue that a new smaller-scale framework is needed to improve our understanding of sediment dynamics in storms and tsunamis for identifying the differences in the resultant deposits. The ultimate goal is to simulate sediment deposition, transport and erosion on a grain by grain basis. However such an endeavor is computationally and physically challenging. We propose a meso-scale approach with is a hybrid of the particle and concentration paradigm. In our model, we assume that a number of grains travel together, and this cluster of grains can be treated as particle as it moves through the water column. The equation of motion for the grain-cluster particle is, of course, Newtons Second Law of motion. We present the first results with this new model approach. We show that the model reproduces the general macroscopic differences between storm and tsunami deposits. Furthermore we look at the internal structures of storm and tsunami deposits and demonstrate the advantages, limitations, and challenges of this new approach. Please note this is work in progress.