The objective of this chapter is to present the numerical methods utilized in solving the 2D sediment transport equations, subgrid erosion and deposition, and bed sorting equations. Sediments are grouped into representative grain classes. A total-load transport equation is solved for each grain class with the HEC-RAS 2D Transport Module (Sánchez et al. 2020). The transport module solves for the cell-averaged fractional sediment concentration. Fractional and total bed change equations are solved. The bed composition is evolved with bed sorting equations. The transport equations are coupled to each other and the bed change and bed sorting equations utilizing Picard iterations. A full description of the sediment computation algorithm is provided in Section 3.19.