1. A method for creating simulated river data for a prediction model comprising: generating river coastline segments based on river imagery, the river imagery having water location points and river boundaries, the river boundaries including coastline location points; generating river cross sections from the river coastline segments by: (a) receiving a current segment identifier identifying a current segment from the river coastline segments based on the current segment identifier, the current segment having a midpoint, and labeling the midpoint as one end of a river cross section associated with the current segment; (b) receiving an angle range of an angle in a direction of the river; (c) labeling the midpoint of a nearest of the river coastline segments to the current segment within the angle range to the current segment as the other end of the river cross section associated with the current segment; (d) deleting the river cross section associated with the current segment if it intersects with another of the river cross sections; (e) deleting the river cross section associated with the current segment if it does not span the river; (f) restricting the angle range to force the river cross section associated with the current segment to span the river; and (g) repeating steps (a)-(f) until all possible of the river cross sections are created throughout a region covered by the river coastline segments and the river cross sections; generating synthetic bathymetry from the river cross sections; correcting gaps in the river coastline segments; creating a finite element mesh based on the river cross sections, corrected portions of the river coastline segments, the corrected gaps, the river coastline segments, and a river extension; and generating model parameters and input data files based on the synthetic bathymetry, the finite element mesh, boundary nodes, and boundary parameters.