Rainfall Overlay: Difference between revisions

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[[File:Rainfall-Overlay.jpg|thumb|right|200px|Rainfall overlay, also known as the inundation module]]
[[File:Rainfall-Overlay.jpg|thumb|right|200px|Rainfall overlay]]
The Rainfall Overlay is an [[Grid overlay|overlay]] based on the [[Water Module|water module]] calculations, that displays the hazard and impact of heavy rainfall over the project area. Based on the elevation model, terrain roughness and representations of the sewer and water systems, several result types can be displayed.
The Rainfall Overlay is a variant of the [[Water Overlay]], which in turn is a [[Grid overlay|grid overlay]]. Water overlays are connected to the [[Water Module]], a complex hydrological calculation module within the {{software}}.  


A [[Rainfall_Overlay_tutorial|Rainfall Overlay Tutorial]] is available to start working with this overlay.
The Rainfall overlay specializes in displaying the hazard and impact of (heavy) rainfall over the project area. Based on the elevation model, terrain roughness and representations of the sewer and water systems, several result types can be generated by the accompanying Water Module.
<br clear=all>
==Rainfall overlay results==
[[Results (Water Overlay)|Flooding overlay results]]<br>
[[Result type (Water Overlay)#List of Result Types|List of Result Types]]


==Rainfall overlay calculations==
A [[Rainfall_Overlay_tutorial|Rainfall Overlay Tutorial]] is available to get you started with this overlay.
''Main article: [[Rainfall Overlay Calculations (Water overlay)]]


===Calculation Preference===
In order to get more familiar with the different components of the Rainfall Overlay check out Quadrant 2 of the [[Testbed_water_module|Water Module Testbed]]. This Testbed is available to you as a project in the {{software}}.
Here you can manipulate the computation time step by choosing between the option SPEED, AVERAGE and ACCURACY. The computational timesteps will be set according to the Courant criterion:


Δt  = Δx /u<sub>max</sub>
==Rainfall overlay results==
 
The Rainfall Overlay is a Water Overlay that is connected to the Water Module. This Water Module performs two dimensional grid based water simulations for a large set of input data and parameters, configured mostly through a related [[Water Overlay Wizard]]. When a simulation finishes, the module stores the result in the Rainfall overlay based on the selected result type. Only one result type can be stored per Rainfall overlay.
where:
* Δt = computational timestep
* Δx = grid cell size
* u<sub>max</sub> = max velocity, assumed 2.5 (SPEED), 5 (AVERAGE) and 10 (ACCURACY) m&sub3;/s respectively
 
===Grid cell size===
The {{software}} computes flow equations over a rectangular cartesian grid, the grid cell size can be set in the General Tab of the Rainfall Overlay.
Note: if you choose a smaller grid cell size, both the amount of time steps (see Calculation Preference) and amount of computational cells increase.
===Export GeoTiff & Water Balance===
You can export the current result-type as GeoTiff and a waterbalance as Microsoft Excel file.
 
===Debug Info===
''General info''
 
The debug info contains the following information:
* Rain: the amount of rainfall (mm) in the duration of the rainfall event (hours)
* Total Simulation: the simulation period (hours)
* Cells: The dimensions of the simulation: the amount of computational cells and the amount of time steps (cycles)
* Weir flow: the amount of water flown over weirs during simulation (m3)
* Sewer overflow: the amount of water flown over sewer overflows during simulation (m3)
* GPU time: the computation time on GPU (seconds)
* Max Courant avg: the maximum courant numbers reached during the simulation
 
''Water balance''


The water balance is made up of the following components:
The Water Module however, is not restricted to generating only one type of result. Instead it can produce multiple unique result types for one single simulation.
* Land surface: amount of water on the land surface after simulation (m3)
Fortunately it is possible to add additional result type overlays which relate to a particular Rainfall overlay. These are known as [[Result Child Overlay]]s. Again, each child overlay only stores one particular result type.
* Water surface: amount of water stored on water cells after simulation (m3)
* Building storage: amount of water stored in building storage (m3)
* Sewer storage: amount of water stored in sewers after simulation (m3)
* Underground storage: amount of water stored in the sub-soil after simulation (m3)
* Evaporated: amount of water evaporated after simulation (m3)
* Outlet: amount of water extracted from the model during the simulation via outlets of water areas or sewer pumps (m3).


==Overlay Keys==
Apart from multiple result types, the Rainfall overlay can also store result data of multiple, intermediate simulation results, instead of just a single end result. These intermediate simulation results are known as [[timeframes (Water Overlay)|timeframes]].


Keys referring to area attributes
For the full list of result types, see [[Result type (Water Overlay)#List of Result Types|List of Result Types]].
{| class="wikitable"
! Attribute
! Unit
! Description
|-
|Water Level
|m + datum
|initial water level, relative to datum, for all water cells in a water area
|-
|Outlet
|m3/s
|water abstraction for all water cells in a water area
|-
|Sewer Storage
|m         
|available storage in sewers at the start of simulation in a sewer area
|-
|Sewer Pump Speed
|m3/s
|sewer water abstraction for all cells in a sewer area
|}


Keys referring to structures (building attributes)
For other results, which are not overlay results, but still related to the simulation for a particular Rainfall overlay, see [[Results (Water Overlay)|Rainfall overlay results]].
{| class="wikitable"
! Attribute
! Unit
! Description
|-
|Weir Height
|m + datum
|weir crest level
|-
|Weir Width
|m
|the width of the crest of a weir
|-
|Weir Coefficient
|
|linear weir coefficient for accounting discharge & contraction losses
|-
|Culvert Speed
|m3/s
|the discharge capacity of a culvert
|-
|Pump Speed
|m3/s
|the capacity of a pump
|-
|Sewer Overflow Height
|m + datum
|the height of a crest of a sewer overflow
|-
|Sewer Overflow Speed
|m3/s
|the discharge capacity of a sewer overflow
|}


==Overlay Attributes==
==Module==
{| class="wikitable"
A Rainfall Overlay can be configured by opening the Rainfall Overlay Wizard. More in-depth information can be found under each of the categories below.
! Attribute
{{Water Module buttons}}
! Unit
! Description
|-
|ALLOWED_WATER_INCREASE_M
|m
|increment by which the water level on a water cell is allowed to increase before the depth is shown in the water stress result type
|-
|IMPACT FLOOD_THRESHOLD_M
|m
|maximum waterdepth around a building where after the building is assumed impacted
|-
|MIN_SLOPE
|
|slope whereunder the pressure slope is assumed 0
|-
|SEWER_OVERFLOW_THRESHOLD
|
|fraction of storage whereafter sewer overflows take place
|-
|SIMULATION_TIME_HOURS
|hours
|simulation time
|}


==References==
==References==
# STOWA (2017) ∙ Benchmark Inundatiemodellen, Modelfunctionaliteiten en testbankberekeningen ∙ found at: https://ruimtelijkeadaptatie.nl/publish/pages/129612/benchmark_inundatiemodellen_stowa_2017.pdf (last visited 2018-08-13)
# [[Water Module Theory#Formulas|Water model formulas]]
 
==How-to's==
* [[How-to add and remove an overlay|Add and remove an overlay]]
* [[How-to edit an overlay legend|Edit an overlay legend]]
* [[How-to_add_Subsidence_Overlay|Combine with Subsidence Overlay]]


{{Template:Overlay nav}}
{{WaterOverlay output nav}}
{{Overlay nav}}

Latest revision as of 13:47, 17 January 2023

Rainfall overlay

The Rainfall Overlay is a variant of the Water Overlay, which in turn is a grid overlay. Water overlays are connected to the Water Module, a complex hydrological calculation module within the Tygron Platform.

The Rainfall overlay specializes in displaying the hazard and impact of (heavy) rainfall over the project area. Based on the elevation model, terrain roughness and representations of the sewer and water systems, several result types can be generated by the accompanying Water Module.

A Rainfall Overlay Tutorial is available to get you started with this overlay.

In order to get more familiar with the different components of the Rainfall Overlay check out Quadrant 2 of the Water Module Testbed. This Testbed is available to you as a project in the Tygron Platform.

Rainfall overlay results

The Rainfall Overlay is a Water Overlay that is connected to the Water Module. This Water Module performs two dimensional grid based water simulations for a large set of input data and parameters, configured mostly through a related Water Overlay Wizard. When a simulation finishes, the module stores the result in the Rainfall overlay based on the selected result type. Only one result type can be stored per Rainfall overlay.

The Water Module however, is not restricted to generating only one type of result. Instead it can produce multiple unique result types for one single simulation. Fortunately it is possible to add additional result type overlays which relate to a particular Rainfall overlay. These are known as Result Child Overlays. Again, each child overlay only stores one particular result type.

Apart from multiple result types, the Rainfall overlay can also store result data of multiple, intermediate simulation results, instead of just a single end result. These intermediate simulation results are known as timeframes.

For the full list of result types, see List of Result Types.

For other results, which are not overlay results, but still related to the simulation for a particular Rainfall overlay, see Rainfall overlay results.

Module

A Rainfall Overlay can be configured by opening the Rainfall Overlay Wizard. More in-depth information can be found under each of the categories below.


References

  1. Water model formulas