| Depth | Depth of surface storage [m]. State variable |
| DepthOld | Depth of surface storage in last time step[m]. |
| Evap | Evaporation rate from surface [m/s] |
| Infil | Infiltration rate from surface to lower layer [m/s] |
| ManningM | Manning´s M for overland flow over the surface. |
| Outflow | Outflow rate (overflow/runoff) from surface [m/s] |
| Slope | Slope of surface (fraction). |
| StorageHeight | Height of surface storage [m]. Above this depth, overflow occurs. |
| SurfaceAlpha | Helper variable, containing ManningM*sqrt(Slope). If zero, routing is disabled. |
| UsesRouting | Bool indicating if routing is enabled (SurfaceAlpha is greater than zero). |
| VegetationFraction |
The fraction of the surface storage that is filled with vegetation.
Default value: 0. Unit: [m]. |
| Volume | Volume of water per area [m] contained on surface |