Drainage (Water Overlay)

Drainages provide connections between the saturated ground layer and nearby waterways, draining groundwater to levels which are optimal for agriculture. Drainage can be passive, where water drains based on water head differences, or active, where the water is pumped from the drain to the nearby waterway.

A drainage is an area-based building.

Drainage diameter (Water Overlay)

Key	Unit	Range	Description	Default value
DRAINAGE_Q	m3 per second		The maximum pump flow capacity, defined in cubic meters per second.	1
DRAINAGE_DATUM	datum	-10000 to 10000	The datum height (int meters) of the drainage.	-10000
DRAINAGE_ACTIVE	boolean	0 or 1	Whether the drainage is actively pumped.	False
DRAINAGE_OVERFLOW_THRESHOLD	m + datum	-10000 to 10000	The threshold of the water end-point of the drainage.	n/a

Notes

A drainage should have a part that overlaps with land and a part that overlaps with water. These should be two separate polygons. Neither polygon should overlap with the edge of the waterway.

There are three use cases that can be modeled using a drainage:

Passive Drainage

A passive drainage lets water flow from the drainage pipes into the waterway. I should therefor always have a positive Q.

Active Drainage Negative Q

A active drainage with a negative Q can pump water out from the waterway into the drainage pipes. The pump will keep pumping until the level in the waterway drops to the Drainage overflow threshold (Water Overlay) or the the groundwater reaches: Drainage datum (Water Overlay) + Drainage diameter (Water Overlay) / 2.

Active Drainage Positive Q

A active drainage with a positive Q can pump water from the drainage pipes up into a waterway with a higher water level. The pump will keep pumping until the level in waterway reaches the Drainage overflow threshold (Water Overlay) or the the groundwater drops to: Drainage datum (Water Overlay) - Drainage diameter (Water Overlay) / 2.