Compaction formula (Subsidence Overlay): Difference between revisions

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The amount of subsidence due to compaction is calculated by the following formula:
The amount of subsidence due to compaction is calculated by the following formula:
{{code|1= Subsidence = (Peat fraction * PEAT_A + Top layer * TOP_LAYER_A) * log10(days)
+ Peat fraction * PEAT_B
+ Top Layer * TOP_LAYER_B
+ Height Increase * HEIGHT
}}


* The peat fraction and thickness of the top layer are attributes in the project. The exact attributes which provide these can be configured as [[#Keys|keys]] in the overlay.
<math>S_{sub} = a_{peat} \cdot p_{x,y} + a_{tl} \cdot tl_{x,y} \cdot log10(t_{days}) + b_p \cdot p_{x,y} + b_{tl} \cdot tl_{x,y}+ a_h \cdot \Delta{h}</math>
* The height increase is a result of the actions taken during a [[session]], such as the creation of [[levee]]s.
 
* The days are equal to the number of days in a year, times the current year being calculated.
* <math>p_{x ,y}</math> is the [[Peat fraction (Subsidence Overlay)|peat fraction]] of the cell at coordinate (x,y)
* PEAT_A (0.015853041) is a constant, for the effect of the peat fraction over time.
* <math>tl_{x,y}</math> is the [[top layer thickness]] of the cell at coordinate (x,y)
* PEAT_B (0.02348519) is a constant, for the base effect of the peat fraction.
* <math>\Delta_h</math> The height increase as a result of the actions taken during a [[session]], such as the creation of [[levee]]s.
* TOP_LAYER_A (0.006617643) is a constant, for the effect of the top layer thickness over time.
* <math>t_{days}</math> is the number of days in a year times the current year being calculated.
* TOP_LAYER_B (-0.010061616) is a constant, for the base effect of the top layer thickness.
* <math>a_{peat}</math> is the first regression constant (-0.015853041) for the effect of the peat fraction and time in days.
* HEIGHT (0.200468677) is a constant, for the base effect of the height of added materials.
* <math>b_{peat}</math> is the second regression constant (0.02348519) for the effect of the peat fraction.
* <math>a_{tl}</math> is the first regression constant (-0.006617643) for the top layer thickness and time in days.
* <math>b_{tl}</math> is the second regression constant (0.010061616) for the top layer thickness.
* <math>a_h</math> is a regression constant (-0.200468677) for the change in surface height, for example caused by added materials.


This formula is based on provided expert data in the form of a reference table, indicating the amount of subsidence based on the parameters used in the formula above. The formula's results conform to the reference table to within an average of a tenth of the margin of error of the original table.
This formula is based on provided expert data in the form of a reference table, indicating the amount of subsidence based on the parameters used in the formula above. The formula's results conform to the reference table to within an average of a tenth of the margin of error of the original table.

Revision as of 16:46, 8 February 2021

The amount of subsidence due to compaction is calculated by the following formula:

  • is the peat fraction of the cell at coordinate (x,y)
  • is the top layer thickness of the cell at coordinate (x,y)
  • The height increase as a result of the actions taken during a session, such as the creation of levees.
  • is the number of days in a year times the current year being calculated.
  • is the first regression constant (-0.015853041) for the effect of the peat fraction and time in days.
  • is the second regression constant (0.02348519) for the effect of the peat fraction.
  • is the first regression constant (-0.006617643) for the top layer thickness and time in days.
  • is the second regression constant (0.010061616) for the top layer thickness.
  • is a regression constant (-0.200468677) for the change in surface height, for example caused by added materials.

This formula is based on provided expert data in the form of a reference table, indicating the amount of subsidence based on the parameters used in the formula above. The formula's results conform to the reference table to within an average of a tenth of the margin of error of the original table.