Evergreen Trees

Tip

  1. Need help? Please let us know in the SUEWS Community.

  2. Please report issues with the manual on GitHub Issues (or use Report Issue for This Page for page-specific feedback).

  3. Please cite SUEWS with proper information from our Zenodo page.

4.3.12. Evergreen Trees#

Properties for evergreen trees and shrubs.

Evergreen vegetation maintains foliage year-round, providing consistent evapotranspiration and shading. Common in urban parks and residential areas, these surfaces have relatively low albedo and high roughness lengths.

Parameters:

sfr#

Surface fraction of grid area covered by this surface type

Unit:

dimensionless

Example:

0.14285714285714285

emis#

Surface emissivity for longwave radiation

Unit:

dimensionless

Example:

0.95

ohm_threshold_summer_winter#

Summer/winter threshold based on temperature for OHM calculation

Unit:

degC

Example:

0.0

ohm_threshold_wet_dry#

Soil moisture threshold determining whether wet/dry OHM coefficients are applied

Unit:

dimensionless

Example:

0.0

ohm_coef#

The ohm_coef parameter group is defined by the Seasonal/Wetness OHM Coefficients structure.

soil_depth#

Depth of soil layer below surface for hydrological calculations, controlling sub-surface water storage and drainage processes. Site-specific value typically determined from soil surveys or borehole data

Unit:

mm

Default:

None (optional)

soil_store_capacity#

Maximum water storage capacity of soil layer, representing total water holding capacity between field capacity and wilting point. Site-specific value dependent on soil texture, structure, and depth

Unit:

mm

Default:

None (optional)

state_limit#

Minimum water storage capacity for state change

Unit:

mm

Example:

10.0

wet_threshold#

Surface wetness threshold for OHM calculations

Unit:

dimensionless

Example:

0.5

saturated_hydraulic_conductivity#

Saturated hydraulic conductivity of soil layer, controlling water drainage rate through fully saturated soil. Site-specific value determined from soil texture (higher for sandy, lower for clay); typically measured via laboratory or field infiltration tests

Unit:

mm s-1

Default:

None (optional)

soil_density#

Bulk soil density

Unit:

g cm^-3

Default:

None (optional)

waterdist#

Water distribution for evergreen trees

The waterdist parameter group is defined by the Water Distribution structure.

storage_drain_params#

Storage and drain parameters

The storage_drain_params parameter group is defined by the Drainage Parameters structure.

snowpack_limit#

Limit of snow that can be held on surface

Unit:

mm

Example:

10.0

thermal_layers#

Thermal layers for the surface

The thermal_layers parameter group is defined by the Thermal Layers structure.

irrigation_fraction#

Fraction of surface area that can be irrigated

Unit:

dimensionless

Example:

0.0

ref#

The ref parameter group is defined by the Reference Info structure.

alb_min#

Minimum albedo (trees: leaf-off; grass: full-leaf)

Unit:

dimensionless

Example:

0.2

alb_max#

Maximum albedo (trees: leaf-on; grass: sparse or senesced)

Unit:

dimensionless

Example:

0.3

beta_bio_co2#

Light-saturated gross photosynthesis rate of the canopy

Unit:

umol m-2 s-1

Default:

None (optional)

beta_enh_bioco2#

Enhanced photosynthesis coefficient related to vegetation fraction

Unit:

umol m-2 s-1

Example:

0.7

alpha_bio_co2#

Mean apparent ecosystem quantum yield (initial slope of light-response curve)

Unit:

umol CO2 umol photons^-1

Default:

None (optional)

alpha_enh_bioco2#

Enhanced quantum yield coefficient related to vegetation fraction

Unit:

umol CO2 umol photons^-1

Example:

0.9

resp_a#

Base respiration rate coefficient

Unit:

umol m-2 s-1

Default:

None (optional)

resp_b#

Respiration temperature sensitivity coefficient

Unit:

K-1

Default:

None (optional)

theta_bio_co2#

Curvature parameter for non-rectangular hyperbola at light saturation

Unit:

dimensionless

Default:

None (optional)

max_conductance#

Maximum surface conductance

Unit:

mm s-1

Example:

0.5

min_res_bioco2#

Minimum soil respiration rate for cold-temperature limit

Unit:

umol m-2 s-1

Example:

0.1

lai#

Leaf area index parameters

The lai parameter group is defined by the LAI structure.

ie_a#

Irrigation efficiency coefficient-automatic

Unit:

dimensionless

Example:

0.5

ie_m#

Irrigation efficiency coefficient-manual

Unit:

dimensionless

Example:

0.6

fai_evergreen_tree#

Frontal area index of evergreen trees

Unit:

dimensionless

Default:

None (optional)

height_evergreen_tree#

Evergreen tree height

Unit:

m

Default:

None (optional)