Surface model (Water Overlay) and Sewer overflow (Water Overlay): Difference between pages

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Sewer overflows are points where water is moved from the [[sewer model (Water Overlay)|sewer]] to the [[surface model (Water Overlay)|surface water system]]. A sewer overflow will allow water to flow through if the water in the sewer exceeds the [[Sewer_overflow_threshold_model_attribute_(Water_Overlay)|SEWER_OVERFLOW_THRESHOLD]], and the water in the connected sewer exceeds the height of the terrain at the location of the sewer overflow. It will then allow water to flow out of all sewers part of that sewer area.
The [[Water Module]]'s primary function is the simulation of the 2-dimensional flow of water on the surface. In order to simulate flowing water, the project area is discretized into x by y cells, based on the configured [[grid cell size]].  


Secondly a model is required which describes the rules that need to be followed. For this we use the two-dimensional Saint-Venant system, which reads:
[[File:waterwizard_icon_sewer_overflow.png]] A sewer overflow is a {{inlink|lcase=1|Point-based constructions}}. It must intersect with a [[Sewer_area_(Water_Overlay)|Sewer area]] and a [[Water_level_area_(Water_Overlay)|water level area]], but does not need to intersect with an actual sewered construction.
[[File:2D-Saint-Venant_system.png|left]]
{{Overlay attribute
where:
|attribute=[[Sewer_overflow_attribute_(Water_Overlay)|SEWER_OVERFLOW]]
: h<sub>t</sub> = height of water column on time t
|unit={{mdatum}}
: u<sub>t</sub> = flow speed in the x direction on time t
|description=The height at which the Sewer Overflow is situated. The average height at which the related Sewer Area will be situated is relative to this height.
: v<sub>t</sub> = flow speed in the y direction on time t
|defaultvalue=n/a
: B<sub>x</sub> = slope in the x direction
|icon=[[File:waterwizard_icon_sewer_overflow_height.png]]
: B<sub>y</sub> = slope in the y direction
|attribute2=[[Sewer_overflow_speed_(Water_Overlay)|SEWER_OVERFLOW_SPEED]]
{{clear|left}}
|unit2=m<sup>3</sup>/s
|description2=The maximum speed by which the water flows through the overflow.
|defaultvalue2=10
|icon2=[[File:waterwizard_icon_sewer_overflow_speed.png]]
}}
==Note==
* At most one overflow can exist per sewer area.
* Water will flow when the water height in the Sewer is larger then the Overflow Threshold.
* Sewer overflows will only be created when all sewer areas in which a sewer overflow is placed also intersect with a water level area.
==See also==
* [[Sewer_Overflow_formula_(Water_Overlay)|Sewer overflow formula]]
* [[Sewer_area_(Water_Overlay)|Sewer Area]]
* [[Sewer_model_(Water_Overlay)|Sewer Model]]


In the {{software}} this model is implemented using the ''Well Balanced Positivity Preserving Central-Upwind Scheme'' described in Kurganov and Petrova (2007)<ref name="Kurganov2"/>.
{{WaterOverlay hydraulic structure nav}}
For more information about the implementation, see [[Surface_flow_formula_(Water_Overlay)|Surface flow formula]].
 
[[File:Waterlevel_schematic.png|right|x200px|frame|B = surface elevation of grid cell<br>h = water height of grid cell<br>w = water level of grid cell.]]
The implemented method rewrites the '''h''' from the original Saint-Venant system to <code>w = h + B</code>. See the image on the right for clarification on the terms water level (w), surface (or bottom) elevation (B) and water height (h).
 
====Flowing water====
Based on variations in the surface elevation and water levels, which may cause unbalance, water will start flowing, until it eventually is balanced in terms of water level and fluxes ''hu'' and ''hv''.
 
{{clear|right}}
 
===Water level initialization===
In theory, each grid cell can have a unique water level and accompanying water height. In practice though, water levels are often initialized for large groups of cells, since it is assumed that a particular area within the project area has a given [[water level (Water Overlay)|water level]]. Therefore, the surface water level is initialized based on hydrological features.
We make the following distinction:
* [[water level (Water Overlay)|Water level]]s of [[terrain water (Water Overlay)|water terrains]].
* [[inundation level (Water Overlay)|Potential water level]]s for inundated land.
 
For all [[Terrain water (Water Overlay)|water terrain]]s, the amount of water set on the grid cell is such that the resulting water level in that location is equal to the [[Water level (Water Overlay)|WATER_LEVEL]] attribute provided by the [[Water level area (Water Overlay)|Water level area]]. If no water level area is overlapping that grid cell, or the water level is below the [[terrain height (Water Overlay)|surface elevation]] of the grid cell, the water height is assumed to be 0 and the water level equal to the surface elevation.
 
For the second case, [[Inundation area (Water_Overlay)|inundation area]]s have been added to the model. Water is placed in all grid cells which are covered by an inundated area, (regardless of the terrain type in that location, in contrast to the water level areas), such that the resulting water level is again equal to the inundation area's [[Inundation level (Water Overlay)|INUNDATION_LEVEL]] attribute. If no inundation area is overlapping that grid cell, or the inundation level is below the surface elevation of the grid cell, the water height is assumed to be 0 and the water level equal to the surface elevation.
 
The terrain height is defined by the [[terrain height]] in the project. The surface height is further influenced by the height of constructions present in the project (bounded by [[Design flood elevation m model attribute (Water Overlay)|DESIGN_FLOOD_ELEVATION_M]]) and by the [[Breach height (Water Overlay)|BREACH_HEIGHT]] of [[Breach (Water Overlay)|breaches]].
 
==Notes==
* Water can be added to and removed from the described surface system by the [[Rain model (Water Overlay)|rain]], [[Evaporation model (Water Overlay)|evaporation]] and [[Infiltration model (Water Overlay)|infiltration model]], as well as certain [[Hydraulic structures (Water Overlay)|hydraulic structures]], [[Sewer model (Water Overlay)|sewer]]s and [[Breach (Water Overlay)|breach]]es.
* Underground flow uses a different flow system and formula's, described in [[Underground model (Water Overlay)|underground model]].
* In addition to water flowing between adjacent grid cells, water can also flow through [[Hydraulic structures (Water Overlay)|hydraulic constructions]].
 
==Related formulas==
* [[Surface water level formula (Water Overlay)|Surface water level formula]]
* [[Surface flow formula (Water Overlay)|Surface flow formula]]
* [[Surface infiltration formula (Water Overlay)|Surface infiltration formula]]
 
* [[Culvert formula (Water Overlay)|Culvert formula]]
* [[Weir formula (Water Overlay)|Weir formula]]
* [[Breach growth formula (Water Overlay)|Breach growth formula]]
* [[Breach flow formula (Water Overlay)|Breach flow formula]]
* [[Pump formula (Water Overlay)|Pump formula]]
* [[Sewer Overflow formula (Water Overlay)|Sewer overflow formula]]
* [[Inlet formula (Water Overlay)|Inlet formula]]
 
==Related models==
* [[Rain model (Water Overlay)|Rain model]]
* [[Evaporation model (Water Overlay)|Evaporation model]]
* [[Sewer model (Water Overlay)|Sewer model]]
* [[Storage model (Water Overlay)|Storage model]]
* [[Substance flow model (Water Overlay)|Substance flow model]]
 
==References==
<references>
<ref name="Kurganov2">Kurganov A, Petrova G (2007) ∙ A Second-Order Well-Balanced Positivity Preserving Central-Upwind Scheme for the Saint-Venant System ∙ found at: http://www.math.tamu.edu/~gpetrova/KPSV.pdf (last visited 2019-04-11)</ref>
</references>
 
{{Template:WaterOverlay_nav}}
{{Water Module buttons}}
{{Water Module buttons}}

Revision as of 12:30, 19 June 2019

Sewer overflows are points where water is moved from the sewer to the surface water system. A sewer overflow will allow water to flow through if the water in the sewer exceeds the SEWER_OVERFLOW_THRESHOLD, and the water in the connected sewer exceeds the height of the terrain at the location of the sewer overflow. It will then allow water to flow out of all sewers part of that sewer area.

Waterwizard icon sewer overflow.png A sewer overflow is a point-based constructions. It must intersect with a Sewer area and a water level area, but does not need to intersect with an actual sewered construction. Template:Overlay attribute

Note

  • At most one overflow can exist per sewer area.
  • Water will flow when the water height in the Sewer is larger then the Overflow Threshold.
  • Sewer overflows will only be created when all sewer areas in which a sewer overflow is placed also intersect with a water level area.

See also