We have studied two numerical strategies for solving a coupled system of dictinct nonlinear equations governing sediment transport in Lake Okeechobee. Using high-resolution bathymetry data of Lake Okeechobee, Florida, we study the numerical properties of the two strategies, from 1 core to 512 cores. The fully-explicit scheme is straightforward to implement and requires a relatively small amount of computation per time step. However, this simple numerical strategy has to use small time steps to ensure stability. These small time steps may render the explicit solver impractical for long-term and high-resolution basin simulations. As a comparison, we have implemented a semi-implicit scheme, where the two partial differential equations at each time step are solved implicitly in sequence. Numerical experiments show that this semi-implicit scheme is numerically stable even for very large time steps. Using a multicore-based cluster, we have carried out parallel simulations of sediment transport along a river chanel and into Lake Okeechobee.