Subsidence Overlay: Difference between revisions
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* '''Clay thickness''': The thickness of the layer of clay on the top of the soil, in meters. The thicker the layer, the less subsidence occurs. Should be 0, or greater than 0. | * '''Clay thickness''': The thickness of the layer of clay on the top of the soil, in meters. The thicker the layer, the less subsidence occurs. Should be 0, or greater than 0. | ||
When the file is prepared, it can be [[GeoJSON#How to load a GeoJSON file into the engine | When the file is prepared, it can be [[GeoJSON#How to load a GeoJSON file into the engine|imported]] via the option in the ribbon, or by dragging the file into the Engine. The file must be imported as [[area]]s. | ||
|imported]] via the option in the ribbon, or by dragging the file into the Engine. The file must be imported as [[area]]s. | |||
===Oxidation=== | ===Oxidation=== | ||
Revision as of 13:44, 24 July 2017
What is the subsidence overlay
The subsidence overlay is a grid overlay, and part of the subsidence collection of overlays. It shows which places in the 3D world are subject to subsidence due to oxidation and/or compaction of peat.
How the subsidence overlay calculates
Subsidence is currently composed of 2 forms of reduction of peat: oxidation and compaction. These forms of subsidence are both relevant for the complete picture of subsidence, but are, in principle, calculated via separate formulas. The results of these formulas are added together to get the total amount of subsidence.
Oxidation
Peat, when exposed to oxygen, can oxidize. In this process the peat combines with the air to form CO2, reducing the total mass and volume of the peat. The amount of oxidation depends on the clay thickness, because clay may insulate the peat, preventing it from oxidizing. It also depends on the (lowest) ground water level in relation to the surface of the land.
For information on the exact calculation of subsidence due to oxidation, see the article on Subsidence calculation.
Compaction
Peat is a porous and relatively soft terrain type, meaning it can be compressed. Based on the amount of peat in the ground, the density of the top layer, and the net height increase.
For information on the exact calculation of subsidence due to compaction, see the article on Subsidence calculation.
Multi-year calculations
Subsidence is calculated in 1-year steps. For each year, the amount of subsidence is calculated. That amount is then used to recalculate the input parameters for the overlay. The next 1-year step is then calculated.
For more information on the way the multi-year calculation is performed, see Subsidence calculation.
How to configure the subsidence overlay
When the subsidence overlay is added to a project, there is some minimum information required for a calculation. The compaction calculation already functions based on data present in the engine, but requires a running session and specific actions to be taken. The oxidation calculation can show results without taking actions, provided that the required data is loaded in.
Import oxidation data
It is possible to load in your own GeoJSON file with information which is relevant to the oxidation calculations. When this data is loaded in, results of the calculations will become visible in the 3D world when the overlay is selected.
To import you own file, you must prepare a GeoJSON file with the specified data in the correct format. The file should contain the following data:
- Ground water level: A ground water level, in meters from the surface of the land. The larger the value, the dryer the soil is. Should be greater than 0. (Can also be 0, but there will be no subsidence then.)
- Clay thickness: The thickness of the layer of clay on the top of the soil, in meters. The thicker the layer, the less subsidence occurs. Should be 0, or greater than 0.
When the file is prepared, it can be imported via the option in the ribbon, or by dragging the file into the Engine. The file must be imported as areas.
Oxidation
- Select in the editor '3D World' from the ribbon
- Select 'Overlays' > 'Edit overlays' from the ribbon bar
- Select the desired overlay'*' from the drop down menu on the bottom of the left panel
- Select 'Add' from the bottom of the left panel
- Fill in parameters on the right panel, as required for some overlays
- The overlay icon will now appear under the mini map'**'