# Model attributes (Water Overlay)

The Water Overlay's model calculations depend on a number of calculation-wide parameters. These parameters are available as attributes of the water overlay and can be modified as such.

Icon | Attribute | Unit | Description | Default value |
---|---|---|---|---|

ALLOWED_WATER_INCREASE_M | m | The amount by which the water level on a water terrain must increase before it is considered stressed by water. This is used to compute the WATER_STRESS result type. | n/a | |

AVG_SHORE_WIDTH_M | length | With the surface water mode set to Grid Averaging, identified water average areas can be extended to include nearby shorelines within the configured distance. | n/a | |

CULVERT_DEM_THRESHOLD_M | m | The maximum distance a culvert's height can be below the terrain, for the terrain height to be adjusted to the threshold of the culvert. | n/a | |

DESIGN_FLOOD_ELEVATION_M | m | Constructions in the 3D world are assumed to have at most this height compared to the surface of the terrain. Greater values can create a more accurate model but will impact performance. | n/a | |

GRAVITY | m/s² | Used constant for gravitational acceleration | n/a | |

GROUND_BOTTOM_DISTANCE_M | m | Assumed distance under the terrain surface where the soil becomes impenetrable for water. | n/a | |

GROUND_WATER | nominal value | Whether and how water in the underground is simulated during the calculation. | n/a | |

GROUND_WATERTABLE_WITH_SURFACE | boolean | Whether the ground watertable result type should also include the surface water level, when the groundwater levels are close to the surface. | n/a | |

IMPACT_FLOOD_THRESHOLD_M | m | The amount of water a construction must experience before it is considered impacted by water. | n/a | |

IMPACT_RANGE_M | m | the width in meters of the water next to or against the building that have to be flooded before the building is considered impacted by water. | n/a | |

INCLUDE_BRIDGE_ELEVATION | boolean | Whether to include bridges in the elevation model used for the water calculations. | n/a | |

INCREASED_RESOLUTION | boolean | Load the DEM at twice the resolution. | n/a | |

LIMIT_AREA | boolean | Whether calculations should occur in this area or not. | n/a | |

LIMIT_RAIN | nominal value | Whether rainfall can be overridden by rainfall defined in rain areas across the project area. | n/a | |

MAX_WATER_BOTTOM_M | m + datum | The maximum height for the bottoms of water terrains. Any water terrain with a bottom at a higher datum height has its bottom lowered to this value. | n/a | |

MAX_WATER_DEPTH_M | m | The maximum depth of water on a cell that is able to move horizontally. This parameter can be set to influence the wave part in the Saint-Venant equations. | n/a | |

MIN_MAX_ELEVATION | boolean | Whether to use highest and lowest elevations found for a grid cell for land and water respectively when interpreting the elevation model. | True | |

MINIMAL_CULVERT_DIAMETER_M | m | The minimal culvert diameter. | n/a | |

OBJECT_CORRECTION | boolean | Whether to move hydraulic constructions if they would otherwise be inactive due to overlap with another hydraulic construction. | n/a | |

SEEPAGE_FLUCTUATION | m | The additional head of higher areas outside the project causing groundwater seepage. | n/a | |

SEWER_OVERFLOW_THRESHOLD | fraction (m/m) | How much of a sewer's storage must be filled with water before the sewer overflows are allowed to overflow water. | n/a | |

SHORELINE | boolean | Whether to automatically fill cells near a water terrain when there is a mismatch between the extend of the water terrain and the DEM. | n/a | |

SHOW_DURATION_FLOOD_LEVEL_M | m | The amount of water which must be present in a specific location before the duration of surface water can be recorded. This is used to compute the SURFACE_DURATION result type. | n/a | |

STABILIZER_ANGLE | angle (0-90°) | A partly flooded cell (especially at the edges of waterways) can become unstable when the angles in X and Y direction are too far apart. In this case the fluxes in U and V cannot easily be resolved mathematically while preserving balance. To prevent unrealistic fluxes from appearing, only the flux in the primary direction will be preserved. A stabilizer angle of zero means that all cells can be considered partly flooded cells, while an angle of 90 degrees will disable the stabilizer. | n/a | |

START_DATE_MS | timestamp | The date and time which is considered the starting moment of the simulation. | n/a | |

SURFACE_WATER_EVAPORATION_FACTOR | m | The factor by which the weather evaporation factor is multiplied to compute the amount of evaporation which takes place on the surface. | n/a | |

SURFACE_WATER | nominal value | Whether and how water on the surface is simulated during the calculation. | n/a | |

TIMEFRAMES | integer | The number of intermediate results recorded during the calculation. Each timeframe becomes a snapshot of data which can be viewed and analysed. | n/a | |

WEIR_DAM_MULTIPLIER | integer | The width with which the weir's dam should be generated perpendicular to it's direction, relative to its flow width. | 3 |