{
  "problem": "MacDonald-type steady channel flow on a 2D grid (A1F-001's M1 depth profile, uniform across the channel).",
  "L": 1000.0,
  "W": 100.0,
  "q_m2s": 0.2,
  "n_manning": 0.03,
  "g": 9.81,
  "boundaries": {
    "west": "unit discharge q = 0.2 m²/s",
    "east": "exact depth h(L) = 0.748 m",
    "north_south": "slip walls"
  },
  "initial_condition": "uniform depth h(L), velocity q/h",
  "bed": "references.macdonald_2d.bed_elevation (zb(L) = 0)"
}