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| {{learned|what the rainfall overlay is|how the rainfall overlay can be used|how the rainfall overlay can be configured|what principles govern its calculation}}
| | [[File:Rainfall-Overlay.jpg|thumb|right|200px|Rainfall overlay]] |
| [[File:Rainfall-Overlay.jpg|thumb|left|Rainfall overlay, also known as the inundation module]] | | 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}}. |
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| ==What is the Rainfall 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. |
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| The Rainfall Overlay is an [[Grid overlay|overlay]] 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.
| | A [[Rainfall_Overlay_tutorial|Rainfall Overlay Tutorial]] is available to get you started with this overlay. |
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| A [[Rainfall_Overlay_tutorial|Rainfall Overlay Tutorial]] is available to start working with this overlay.
| | 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}}. |
| <br clear=all>
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| ==Result types==
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| The rainfall overlay is a [[grid overlay]] showing results of heavy rainfall on the surface (flooding), sub-surface (groundwater), open water and sewer system. The following results are produced:
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| {| class="wikitable"
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| ! Result type
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| ! Unit
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| ! Description
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| |-
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| |BASE_GROUNDWATER_DISTANCE
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| |m (below surface)
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| |Initial groundwater level relative to the surface level (NL: ontwateringsdiepte).
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| |-
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| |BASE_TYPES
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| |nominal value
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| |Division of gridcells in water, land or sewer areas that are connected to the sewer.
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| |-f
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| |EVAPORATED
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| |m (mm)¹
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| |Total evaporation over the simulation period
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| |-
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| |IMPACTED_BUILDINGS
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| |nominal value
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| |Constructions impacted by flood: the value from the function value indicator is assigned to a building if the water depth at a grid-cell surrounding the building exceeds the overlay attribute value IMPACT_FLOOD_TRESHOLD_M
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| |-
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| |SEWER_LAST_VALUE
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| |m (mm)¹
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| |The amount of water in the sewer storage at the end of simulation
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| |-
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| |SEWER_MAX_VALUE
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| |m (mm)¹
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| |Maximum amount of water in the sewer storage during the simulation
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| |-
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| |SURFACE_DURATION
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| |s (min)¹
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| |The amount of time the water depth in a cell exceeds the value set in the overlay attribute value SHOW_DURATION_FLOOD_LEVEL_M
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| |-
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| |SURFACE_FLOW
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| |m3/m2
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| |Total volume of water passed a grid-cell, scaled by the cell surface (grid cell-size^2)
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| |-
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| |SURFACE_LAST_VALUE
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| |m (min)¹
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| |Water depth at the end of simulation
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| |-
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| |SURFACE_MAX_VALUE
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| |m (min)¹
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| |Maximum water depth during the simulation
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| |-
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| |UNDERGROUND_FLOW
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| |m³/m²
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| |Totall infiltration amount from the surface to groundwater
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| |-
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| |UNDERGROUND_LAST_VALUE
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| |m (mm)
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| |The amount by which the groundwater table has risen above the initial groundwater level at the end of simulation
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| |-
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| |UNDERGROUND_MAX_VALUE
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| |m (mm)
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| |The maximum amount by which the groundwater table has risen above the initial groundwater during the simulation
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| |-
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| |WATER_STRESS
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| |m (mm)
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| |The Maximum water depth during the simulation. At water cells only a water depth is shown if the depth exceeds the overlay attribute value ALLOWED_WATER_INCREASE_M
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| |}
| | ==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. |
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| ¹ the units between () are as displayed in the 3D client. If exported to GTiff the SI-convention is used: meters (m) and seconds (s).
| | 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 Overlay]]s. Again, each child overlay only stores one particular result type. |
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| ==Rainfall Overlay Calculations==
| | 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]]. |
| ''Main article: [[Rainfall Overlay Calculations (Water overlay)]]
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| ==General Tab==
| | For the full list of result types, see [[Result type (Water Overlay)#List of Result Types|List of Result Types]]. |
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| ===Calculation Preference===
| | 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]]. |
| 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:
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| Δt = Δx /u<sub>max</sub>
| | ==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. |
| where:
| | {{Water Module buttons}} |
| * Δt = computational timestep
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| * Δx = grid cell size
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| * u<sub>max</sub> = max velocity, assumed 2.5 (SPEED), 5 (AVERAGE) and 10 (ACCURACY) m&sub3;/s respectively
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| ===Grid cell size===
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| 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.
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| Note: if you choose a smaller grid cell size, both the amount of time steps (see Calculation Preference) and amount of computational cells increase.
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| ===Export GeoTiff & Water Balance===
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| You can export the current result-type as GeoTiff and a waterbalance as Microsoft Excel file.
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| ===Debug Info===
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| ''General info''
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| The debug info contains the following information:
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| * Rain: the amount of rainfall (mm) in the duration of the rainfall event (hours)
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| * Total Simulation: the simulation period (hours)
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| * Cells: The dimensions of the simulation: the amount of computational cells and the amount of time steps (cycles)
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| * Weir flow: the amount of water flown over weirs during simulation (m3)
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| * Sewer overflow: the amount of water flown over sewer overflows during simulation (m3)
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| * GPU time: the computation time on GPU (seconds)
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| * Max Courant avg: the maximum courant numbers reached during the simulation
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| ''Water balance''
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| The water balance is made up of the following components:
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| * Land surface: amount of water on the land surface after simulation (m3)
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| * Water surface: amount of water stored on water cells after simulation (m3)
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| * Building storage: amount of water stored in building storage (m3)
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| * Sewer storage: amount of water stored in sewers after simulation (m3)
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| * Underground storage: amount of water stored in the sub-soil after simulation (m3)
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| * Evaporated: amount of water evaporated after simulation (m3)
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| * Outlet: amount of water extracted from the model during the simulation via outlets of water areas or sewer pumps (m3).
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| ==Overlay Keys==
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| Keys referring to area attributes
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| {| class="wikitable" | |
| ! Attribute
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| ! Unit
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| ! Description
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| |-
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| |Water Level
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| |m + datum
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| |initial water level, relative to datum, for all water cells in a water area
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| |-
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| |Outlet
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| |m3/s
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| |water abstraction for all water cells in a water area
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| |-
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| |Sewer Storage
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| |m
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| |available storage in sewers at the start of simulation in a sewer area
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| |-
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| |Sewer Pump Speed
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| |m3/s
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| |sewer water abstraction for all cells in a sewer area
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| |}
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| Keys referring to structures (building attributes)
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| {| class="wikitable"
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| ! Attribute
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| ! Unit
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| ! Description
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| |-
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| |Weir Height
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| |m + datum
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| |weir crest level
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| |-
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| |Weir Width
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| |m
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| |the width of the crest of a weir
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| |-
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| |Weir Coefficient
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| |linear weir coefficient for accounting discharge & contraction losses
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| |-
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| |Culvert Speed
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| |m3/s
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| |the discharge capacity of a culvert
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| |-
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| |Pump Speed
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| |m3/s
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| |the capacity of a pump
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| |-
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| |Sewer Overflow Height
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| |m + datum
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| |the height of a crest of a sewer overflow
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| |-
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| |Sewer Overflow Speed
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| |m3/s
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| |the discharge capacity of a sewer overflow
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| |}
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| ==Overlay Attributes==
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| {| class="wikitable"
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| ! Attribute
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| ! Unit
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| ! Description
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| |-
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| |ALLOWED_WATER_INCREASE_M
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| |m
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| |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
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| |-
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| |IMPACT FLOOD_THRESHOLD_M
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| |m
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| |maximum waterdepth around a building where after the building is assumed impacted
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| |-
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| |MIN_SLOPE
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| |slope whereunder the pressure slope is assumed 0
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| |-
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| |SEWER_OVERFLOW_THRESHOLD
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| |fraction of storage whereafter sewer overflows take place
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| |-
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| |SIMULATION_TIME_HOURS
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| |hours
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| |simulation time
| |
| |}
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| ==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]] |
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| ==How-to's==
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| * [[How-to add and remove an overlay|Add and remove an overlay]]
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| * [[How-to edit an overlay legend|Edit an overlay legend]]
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| * [[How-to_add_Subsidence_Overlay|Combine with Subsidence Overlay]]
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| {{Template:Overlay nav}} | | {{WaterOverlay output nav}} |
| | {{Overlay nav}} |
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
- Water model formulas
