Quoted from:  https://joss.theoj.org/papers/10.21105/joss.02585

  Hydrodynamic simulations of flow through landscapes allow scientists to answer questions related to the transport of water, nutrients, pollutants, biota, and sediment through waterways (Czuba, David, Edmonds, & Ward, 2019; Duan & Nanda, 2006; Lauzon & Murray, 2018; Rynne, Reniers, Kreeke, & MacMahan, 2016; Wild-Allen & Andrewartha, 2016). In geophysical systems, such as rivers, estuaries, and deltas, hydrodynamic models typically solve the depth-integrated “shallow water” equations in an Eulerian reference frame, which is concerned with fluxes through a given region of space – examples of these solvers include ANUGA (“ANUGA,” 2019), Delft3D (“Delft3D,” 2020), Frehd (Hodges, 2014) and others. However, the spatial and temporal characteristics of the movement of material through a landscape are often better understood using a Lagrangian reference frame (Doyle & Ensign, 2009), which follows the movement of individual objects or parcels. In this paper, we present an open-source Python package, dorado, which provides a transparent and accessible method for researchers to simulate passive Lagrangian particle transport on top of Eulerian hydrodynamic solutions. This mixed Eulerian-Lagrangian methodology adapts the routing functionality from the popular numerical model DeltaRCM (Liang et al., 2015a, 2015b) for use with the outputs of any shallow-water hydrodynamic solver.