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| The subsidence model calculates the gradual downward settling of the ground's surface where a peat layer is present. The considered subsidence takes place due to oxidation and compaction of the peat layer.
| | 3D models in different formats, such as BIM data or a SketchUp model, can be converted to the I3S format with a SLPK file. See the text below to learn more about this. |
| The total subsidence is currently calculated as the result of oxidation and compaction over the years. Oxidation is dependent on the ground water level and the clay thickness. Compaction is dependent on the toplayer thickness, the peat fraction and raised surface terrain.
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| The ground water level is initialized by either raster or surface area data and optionally adjusted each year (indexation). When indexation is active, the surface water level is adjusted for the settling each year and the ground water levels will change accordingly. | | ==What is I3S?== |
| | The I3S (Indexed 3D Scene Layer Specification) is a format for large 3D Geo datasets. The specification is especially designed for streaming large 3D data over the web. The specification originates from Esri and was adopted as a Community Standard by the OGC (Open Geospatial Consortium) in 2017. An I3S dataset is also called a Scene Layer. |
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| The calculation model is configured by the subsidence overlay wizard and it's result are visualized with the [[Subsidence (Overlay)|subsidence overlay]].
| | ==What is an SLPK?== |
| | A Scene Layer Package (SLPK) is a file format for the storage/exchange of one I3S layer. |
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| ==Calculations==
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| During a calculation step, the following aspects are calculated in order:
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| * The temperature at the start of the year is calculated
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| * Based on that, [[#Yearly recalculation of Parameter A|parameter a]] of the oxidation formula is calculated
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| * The [[#Oxidation calculation|oxidation subsidence]] is calculated
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| * The [[#Compaction calculation|compaction subsidence]] is calculated
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| * The surface water levels are lowered by the amount of subsidence times the [[#Indexation|indexation]]
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| * The [[#Ground water depth|ground water level]] is lowered based on subsidence and surface water level indexation
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| * The new ground water level serves as input for the next calculation step
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| ===Yearly recalculation of Parameter A=== | | ==See also== |
| {{:Parameter a recalculation formula (Subsidence Overlay)}} | | * [[How_to_import_i3s_scene_layer_in_new_project|How to create a new project with existing I3S data]] |
| | * [[How_to_prepare_a_3D_plan_for_importing|How to prepare a 3D plan before importing]] |
| | * [[How_to_create_a_SLPK_file|How to create a SLPK file from other 3D data formats]] |
| | * [[How_to_import_a_SLKP_file|How to import a SLKP file into the {{software}}]] |
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| ===Ground water depth===
| | {{Template:GeoDataOverview}} |
| {{:Ground water depth formula (Subsidence Overlay)}} | |
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| ===Oxidation calculation===
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| {{:Oxidation formula (Subsidence Overlay)}}
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| ===Compaction calculation===
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| {{:Compaction formula (Subsidence Overlay)}}
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| ===Subsidence calculation===
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| {{:Subsidence formula (Subsidence Overlay)}}
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| ===Indexation===
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| {{:Indexation formula (Subsidence Overlay)}}
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| ===Terrain height===
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| The height of the terrain can be manipulated during a session by stakeholders taking a land sculpting [[action]], creating [[open water]], or constructing [[levee]]s. These actions will result in settlement, which can be found under the Settlement result type. Creating or demolishing [[construction]]s generally do not change the height of the land, and do not result in changes in the settlement results.
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| ==Configuring overlays==
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| The subsidence overlay has a number of ways to configure it. Both values which serve as input for the overlays directly, as references to attributes of areas which provide input for the calculations.
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| ===Keys===
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| The subsidence overlay has a "Keys" tab in the [[right panel]] in the editor. Most keys are [[attribute]]s of [[area]]s. When the overlay calculates, it will look per [[Grid overlay|grid cell]] for the existence of these attributes.
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| {{Overlay keys|suppresscategory=true|
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| {{:Water level (Subsidence Overlay)}}
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| {{:Water level output (Subsidence Overlay)}}
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| {{:Indexation (Subsidence Overlay)}}
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| {{:Subsidence (Subsidence Overlay)}}
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| {{:Clay thickness (Subsidence Overlay)}}
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| {{:Peat fraction (Subsidence Overlay)}}
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| {{:Toplayer thickness (Subsidence Overlay)}}
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| {{:Drainage (Subsidence Overlay)}}
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| }}
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| Besides these attributes, 2 more model parameters can be configured.
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| {{anchor|Years}}
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| '''Years'''<br>
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| The amount of years to simulate during the calculation, in 1-year steps. It is possible to set this value anywhere between 1 to 1000. This parameter can be configured with the [[Years (Subsidence Overlay)|YEARS]] model attribute of the Subsidence overlay.
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| '''Ground Water Tiff'''<br>
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| If the option to use a Ground Water Tiff is checked, a GeoTiff can be selected to use for the ground water levels. You can either use any of the provided default GeoTiffs, or upload and use your own. <br>
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| Three ground water GeoTiffs covering the Netherlands are available by default. These GeoTiffs are a combination between a high resolution GeoTiff containing ground water levels for rural areas and a low resultion GeoTiff containing ground water levels for city areas, where data from the low resolution GeoTiff was only used to fill the gaps in the high resolution GeoTiff.
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| One of the available ground water GeoTiffs, relevant for the Subsidence, is the Mean Lowest Watertable (MLW, or GLG in Dutch).
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| ===Attributes===
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| The subsidence overlay also has [[Model attributes (Subsidence Overlay)|model attribute]]s. All attributes have a default value, but can be changed to configure the subsidence calculation.
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| {{overlay attributes|suppresscategory=true|allowselflinks=true|
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| {{:Parameter a (Subsidence Overlay)}}
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| {{:B (Subsidence Overlay)}}
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| {{:C (Subsidence Overlay)}}
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| {{:Climate start temp (Subsidence Overlay)}}
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| {{:Climate final temp (Subsidence Overlay)}}
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| {{:Climate soil temp factor (Subsidence Overlay)}}
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| {{:Climate oxidation (Subsidence Overlay)}}
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| {{:Default clay thickness (Subsidence Overlay)}}
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| {{:Default peat fraction (Subsidence Overlay)}}
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| {{:Default top layer thickness (Subsidence Overlay)}}
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| {{:Hi passive drainage (Subsidence Overlay)}}
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| {{:Low passive drainage (Subsidence Overlay)}}
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| {{:Years (Subsidence Overlay)}}
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| }} | |