Subsidence Overlay

Subsidence Overlay

Tutorials

Overview

Theory

Benchmarks

Result types

The overlay offers the following result types:

Result type	Unit	Description
SUBSIDENCE	m change in land height	The amount that the ground has lowered as a result of subsidence, both oxidation and compaction. A positive number means the ground has lowered.
OXIDATION	m change in land height	The amount that the ground has lowered as a result of peat oxidation.
SETTLEMENT	m change in land height	The amount that the ground has lowered as a result of compaction.
HI_GROUND_WATER	m distance from surface to ground water	The distance between the ground surface and the highest ground water level. This number is lower than that of the lowest ground water level. A positive value means the ground water is below the surface of the land. A negative value would theoretically mean the ground water has risen above the surface of the ground.
LOW_GROUND_WATER	m distance from surface to ground water	The distance between the ground surface and the lowest ground water level. This number is higher than that of the highest ground water level. A positive value means the ground water is below the surface of the land. A negative value would theoretically mean the ground water has risen above the surface of the ground.
DAMAGE_DRY	% loss of earnings	The loss of agricultural earnings for drought scenarios, for a particular crop, using the highest and lowest ground water levels adjusted by subsidence. These earnings are calculated by the Waterwijzer Landbouw api. When the water levels in the ground are too low, roots are unable to absorb enough moisture.
DAMAGE_WET	% loss of earnings	The loss of agricultural earnings due to high ground water levels, for a particular crop, using the highest and lowest ground water levels adjusted by subsidence. These earnings are calculated by the Waterwijzer Landbouw api. When the water levels in the ground are too high, subsurface air is replaced by water and plant roots cannot obtain enough oxygen.
DAMAGE_INDIRECT	% loss of earnings	The loss of agricultural earnings due to indirect causes, for a particular crop, using the highest and lowest ground water levels adjusted by subsidence. These earnings are calculated by the Waterwijzer Landbouw api. Indirect causes relate to the type of soil, type of crop and water levels. Taken into account are: soil temperatures in comparison with crop growth calendar; plowing difficulty for a soil and season; sowing problems for the given water levels, crop and soil; germination problems due to sub-optimal water concentrations in the soil; harvest issues due to not fully grown crops; sub-optimal conditions for grassland growth;
DAMAGE_SALT	% loss of earnings	The loss of agricultural earnings due to salt water irrigation or salt water seepage, for a particular crop, using the highest and lowest ground water levels adjusted by subsidence. These earnings are calculated by the Waterwijzer Landbouw api. Too much salt concentration leads to a reduction of water absorption of plant roots, increased toxicity, problems with nutrients absorption and decreased root growth.
DAMAGE_TOTAL	% loss of earnings	The total loss of agricultural earnings for a particular crop, using the highest and lowest ground water levels adjusted by subsidence. These earnings are calculated by the Waterwijzer Landbouw api.

Legend

The legend of the subsidence overlays is automatically calculated, based on the amount of years being calculated by the overlay. The colors will remain constant based on average subsidence per year. I.e. if the amount of years is doubled, the values in the legend, corresponding to specific colors, are doubled as well. Because the legend displays total amounts of subsidence rather than averages, the displayed range of amounts changes when the amount of calculation years changes.

The legend of the ground water overlays is constant, and will display a color from blue through yellow to red to indicate how wet the soil is. The closer the ground water is to the surface of the land, the bluer the overlay. In contrast to the subsidence legends, the range of values for ground water do not change.

Subsidence legend for 30 years
Subsidence legend for 60 years
Ground water legend

Output

The output of all result types of the overlay is in meters. The results can be exported as GeoTiff.

Subsidence output

The output of the grid of each subsidence result type is the subsidence in meters. Depending on the exact result type used, the output is the amount of subsidence as the result of one specific calculation, or the sum of all the calculations of subsidence.

The hover panel will display the following information:

The amount of subsidence taking place over the configured amount of years.
The current surface water level, and to what level it will have changed after the subsidence has taken place.
The indexation policy currently configured for this water level area.

Ground water level output

The output of the grid of each ground water result type is the final distance from the ground water level to the surface of the land in meters.

The hover panel will display the following information:

The level to which the ground water will have changed, after the subsidence has taken place.

Final water level

The overlay can also write the final surface water level to an attribute of an area. The area where the attribute will be written to is the area which has provided the original water level for the overlay.