# Model attributes (Water Overlay)

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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. | 0 | |

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. | 3 | |

AVG_TERRAIN_WIDTH_M | length | With the surface water mode set to Avg Terrain, identified water average areas can be extended to include surrounding terrain within the configured distance. |
1000 | |

AVG_TERRAIN_STORAGE_M | length | When determining the water level of a land cell that will be averaged, the level will ignore the part that is reserved for storage. | 0,05 | |

BREACH_MEASUREMENT_DISTANCE_M | m | Distance from the breach area to the automatically placed measurement point for the downstream water level of the breach, in the direction of the breach. | 100 | |

BRIDGE_ELEVATION | nominal | Specifies the mode by which bridges are include in the elevation model, used for the water calculations. | Lowest | |

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. | 10 | |

DESIGN_FLOOD_ELEVATION_M | m | Buildings in the model 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. | 1 | |

EXTENDED_RECONSTRUCTION | boolean | When selected, a well-balanced reconstruction method for drying and wetting fronts described by Bollermann et. al. is used. This approach is useful when interested in a lake at rest situation and is applied to shorelines. When water flow is more important, this option should be unchecked. |
1 | |

GROUND_BOTTOM_DISTANCE_M | m | Assumed distance under the terrain surface where the soil becomes impenetrable for water. | 10 | |

GROUND_WATER | nominal value | Whether and how water in the underground is simulated during the calculation. | Infiltration Only | |

GROUND_WATER_DEPTH_M | length | The default depth of ground water in meters. | 1 | |

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. | True | |

IMPACT_FLOOD_THRESHOLD_M | m | The amount of water a Building must experience before it is considered impacted by water. | 0,1 | |

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. | 3 | |

INCREASED_RESOLUTION | boolean | Load the DEM at twice the resolution. | False | |

INFILTRATION_FACTOR_S | factor | This value is multiplied with the surface infiltration speed and can be used to adjust the infiltration over time. Default is 1 (no adjustment). | 1 | |

LIMIT_AREA | nominal value | Whether and how calculations in the simulation should be limited to specific locations of the project area. | Entire map | |

LIMIT_RAIN | nominal value | Whether rainfall can be overridden by rainfall defined in rain areas across the project area. | Entire map | |

MAX_INFILTRATION_M | m | Assumed maximum amount of infiltrated water that can be stored underground. | 1 | |

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. | 10000 | |

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. | 1.0 | |

OBJECT_ENTRY_CORRECTION | Integer | How many cells allowed to move hydraulic buildings if they would otherwise be inactive due to overlap with another hydraulic building. | 2 | |

RISE_RATE_DISTANCE_M | m | The water height threshold for computing the Flood rise rate result type. | 1.5 | |

SEEPAGE_FLUCTUATION | m | Optional: The additional head of higher areas outside the project causing groundwater seepage. | 0 | |

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. | 0.9 | |

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. | True | |

SHOW_DURATION_FLOOD_LEVEL_M | m | The amount of water which must be exceeded in a specific location before the duration of surface water can be recorded. This is used to compute the SURFACE_DURATION result type. | 0 | |

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. | 10 | |

START_DATE_MS | timestamp | The date and time which is considered the starting moment of the simulation. | January 1st, 00:00 | |

SURFACE_WATER | Nominal value | Whether and how water on the surface is simulated during the calculation. | Shallow | |

SURFACE_WATER_EVAPORATION_FACTOR | factor | The factor by which the weather evaporation factor is multiplied to compute the amount of evaporation which takes place on the surface. | 1.3 | |

TIMEFRAME_TIMES | integer | The time of individual timeframes in seconds relative to the start date of the simulation. | 0 | |

TIMEFRAMES | integer | The number of intermediate results recorded during the calculation. Each timeframe becomes a snapshot of data which can be viewed and analysed. | 10 | |

UNSATURATED_FRACTION | fraction | The initial fraction of the maximum storage capacity of the unsaturated zone which is filled with water. | 0 | |

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

WEIR_MOVE_INTERVAL_S | seconds | Interval between Weir height adjustments in seconds. The Weir moves up/down to reach the target upstream water level. | 10 | |

WEIR_MOVE_STEP_M | seconds | When the move interval has passed the Weir height is adjusted up/down by this step distance in meters. | 0.01 | |

WEIR_MOVE_RANGE_M | seconds | When the Weir height is adjusted up/down it is clamped by this value in meters. | 0.5 |