Suspended sediment plays a vital role in regional or global cycling of carbon and nutrients by transporting particulate carbon and nutrients from headwaters into large rivers then the ocean. Human activities like reservoir management could fundamentally modify the sediment transportation processes. However, effective representation of sediment is missing in most existing land surface or earth system models, leaving alone the effects of reservoirs on sediment processes. We introduce a physically based river sediment module within an earth system modeling framework, which includes process-based parameterizations of: 1) hillslope soil erosion and discharge into streams; 2) sediment erosion, suspension and transportation through river networks; 3) reservoir regulation based on the inflows from upstream areas and water demand from downstream areas; and 4) sediment trapping by reservoirs. This new sediment module is developed within an earth system modeling framework and to be applied to the river networks at the regional or global scales. Model application and validation will be carried out at the contiguous U.S. using historical streamflow and sediment observations from USGS. The relative contribution of reservoir trapping mechanism and flow regulation on riverine suspended sediment processes will be isolated and quantified through customized numerical experiments. This new sediment module lays the foundation for modeling transportation and transform of particulate C, N and P through rivers into the ocean to close the global C, N and P cycles.