SuctionStress Class Reference

The classical suction depending transpiration Stress curve after Feddes. More...

Inheritance diagram for SuctionStress:

Collaboration diagram for SuctionStress:

Detailed Description

The classical suction depending transpiration Stress curve after Feddes.

The ability of roots to take water from the soil up is limited by the suction pressure (matrix potential) of the soil. The stress is defined using a trapezoid function, with P0 being the pressure, where water uptake is prohibited by saturation. Between P0 and P1 the saturation stress gets lower. Between P1 and P2, no stress occurs (ET=ETpot) and with a pressure below P2, water uptake is limited by drought. P3 indicates the highest suction (lowest pressure) to which plants can extract water (wilting point).

Default values: \(P_0 = \infty, P_1=\infty, P_2=-5m, P_3=-160m\), resulting in no saturation stress and draught stress starting at -5m and a wilting point of -160m.

If one would like to include saturation stress, typical values for P0 and P1 are 0.0m and 0.1m. By changing P2 and P3, you can account for different drought sensibility for different plant types.

Public Member Functions
	SuctionStress (real P0=1e308, real P1=1e307, real P2=-5, real P3=-160)
	Creates a new suction stress function.
cmf::upslope::ET::SuctionStress *	copy () const
	Creates a new copy of this wetness.
virtual real	Tact (const cmf::upslope::SoilLayer *soillayer, real Tpot) const
	Calculates the water stress for a layer.

Public Attributes
real	P0
	Above this pressure, ET=0.0 due to saturation (typical value: 0.0m)
real	P1
	Between P0 and P1 ET raises linear from 0.0 to ETpot (typical value: -0.1m)
real	P2
	Between P1 and P2, ET is unstressed, ET=ETpot (typical value: -5 m)
real	P3
	Between P2 and P3, ET drops linear with the pressure head to zero due to drought (typical value: -160m)

Member Function Documentation

Tact()

virtual real Tact ( const cmf::upslope::SoilLayer * soillayer, real Tpot ) const

virtual

Calculates the water stress for a layer.

Parameters

soillayer	The cmf::upslope::SoilLayer this stress function belongs to
Tpot	Potential Transpiration in mm/day (for the full profile)

Returns

Actual flux from layer in m3/day

Implements RootUptakeStressFunction.