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Model definitions

These views expose the definitions behind the model, including aquifers, snowmelt parameters, curves, and patterns. This is where you look when a node or subcatchment refers to something configured elsewhere.

Edit aquifer and snowmelt configuration while the owner is OPEN or ENDED. Assignments check types and finite numbers immediately, then retain the complete requested values in project units.

The related checks happen together at start(): aquifer ordering and positivity, snowmelt coefficient ordering and removal-sum limits, pattern and subcatchment relationships, and native normalization. If preparation fails, both your requested values and the previous prepared native state remain intact. Repair the declaration and retry without starting the whole project over.

from swmmrs import ConfigurationError, Simulation

with Simulation("model.inp", "model.rpt") as simulation:
    aquifer = simulation.aquifers["UPPER"]
    aquifer.update(
        porosity=0.45,
        field_capacity=0.30,
        wilting_point=0.12,
        upper_evaporation_pattern=simulation.time_patterns["MONTHLY-EVAP"],
    )

    snowmelt = simulation.snowmelt_sets["SNOW-1"]
    snowmelt.update(plowable_fraction=0.25, plow_depth=0.5)
    snowmelt.impervious.update(
        minimum_melt_coefficient=0.05,
        maximum_melt_coefficient=0.01,  # Retained for validation at start().
    )

    try:
        simulation.start()
    except ConfigurationError as error:
        for diagnostic in error.diagnostics:
            print(diagnostic.property_path, diagnostic.message)
        snowmelt.impervious.maximum_melt_coefficient = 0.20
        simulation.start()

Curves, time series, patterns, land uses, pollutants, controls, transects, custom shapes, streets, inlet designs, and other generated model definitions are generation-bound read-only views unless this page explicitly documents an edit operation. A time pattern may be selected by an aquifer, but this interface does not edit the pattern itself.

from swmmrs import Simulation

with Simulation("model.inp", "model.rpt") as simulation:
    print(tuple(simulation.curves))
    curve = simulation.curves["PUMP-CURVE"]
    first_pattern = simulation.time_patterns.by_index(0)

    aquifer = simulation.aquifers["UPPER"]
    pattern = aquifer.upper_evaporation_pattern
    print(curve.id, first_pattern.id)
    if pattern is not None:
        print("selected evaporation pattern:", pattern.id)

See Inspect model definitions for collection names, lookup behavior, relationship traversal, and the editable versus read-only matrix.

Typed, generation-bound views over configured SWMM project objects.

All view instances retain the simulation and project generation that created them. They validate that identity before accessing native state, so retained views cannot silently address a subsequently reopened project.

CLASS DESCRIPTION
Aquifer

Expose a generation-bound editable aquifer definition.
ControlRule

Expose a generation-bound control-rule definition.
Curve

Expose a generation-bound curve definition.
CustomShape

Expose a generation-bound custom-shape definition.
LandUse

Expose a generation-bound land-use definition.
Pollutant

Expose a generation-bound pollutant definition.
SnowmeltParameterSet

Expose a generation-bound editable snowmelt parameter-set definition.
SnowmeltSurface

Expose one fixed snowmelt surface as a live project-unit view.
Street

Expose a generation-bound street definition.
TimePattern

Expose a generation-bound time-pattern definition.
Transect

Expose a generation-bound transect definition.
InletDesign

Expose a generation-bound inlet-design definition.

Aquifer 


              flowchart TD
              swmmrs.objects.Aquifer[Aquifer]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.Aquifer
                


              click swmmrs.objects.Aquifer href "" "swmmrs.objects.Aquifer"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound editable aquifer definition.

METHOD DESCRIPTION
update

Atomically update supplied aquifer fields in project units.
ATTRIBUTE DESCRIPTION
bottom_elevation

Return aquifer bottom elevation in project length units.

TYPE: float

conductivity_slope

Return hydraulic conductivity slope.

TYPE: float

field_capacity

Return field-capacity moisture as a fraction.

TYPE: float

hydraulic_conductivity

Return saturated hydraulic conductivity in project rainfall units.

TYPE: float

lower_evaporation_depth

Return lower-zone evaporation depth in project length units.

TYPE: float

lower_loss_coefficient

Return lower-zone loss coefficient in project rainfall units.

TYPE: float

porosity

Return aquifer porosity as a fraction.

TYPE: float

tension_slope

Return soil moisture tension slope in project length units.

TYPE: float

upper_evaporation_fraction

Return the upper-zone evaporation fraction.

TYPE: float

upper_evaporation_pattern

Return the optional upper-zone evaporation pattern relationship.

TYPE: TimePattern | None

upper_moisture

Return initial upper-zone moisture as a fraction.

TYPE: float

water_table_elevation

Return initial water-table elevation in project length units.

TYPE: float

wilting_point

Return wilting-point moisture as a fraction.

TYPE: float

bottom_elevation property writable 

bottom_elevation: float

Return aquifer bottom elevation in project length units.

conductivity_slope property writable 

conductivity_slope: float

Return hydraulic conductivity slope.

field_capacity property writable 

field_capacity: float

Return field-capacity moisture as a fraction.

hydraulic_conductivity property writable 

hydraulic_conductivity: float

Return saturated hydraulic conductivity in project rainfall units.

lower_evaporation_depth property writable 

lower_evaporation_depth: float

Return lower-zone evaporation depth in project length units.

lower_loss_coefficient property writable 

lower_loss_coefficient: float

Return lower-zone loss coefficient in project rainfall units.

porosity property writable 

porosity: float

Return aquifer porosity as a fraction.

tension_slope property writable 

tension_slope: float

Return soil moisture tension slope in project length units.

upper_evaporation_fraction property writable 

upper_evaporation_fraction: float

Return the upper-zone evaporation fraction.

upper_evaporation_pattern property writable 

upper_evaporation_pattern: TimePattern | None

Return the optional upper-zone evaporation pattern relationship.

upper_moisture property writable 

upper_moisture: float

Return initial upper-zone moisture as a fraction.

water_table_elevation property writable 

water_table_elevation: float

Return initial water-table elevation in project length units.

wilting_point property writable 

wilting_point: float

Return wilting-point moisture as a fraction.

update 

update(**changes: object) -> None

Atomically update supplied aquifer fields in project units.

ControlRule 


              flowchart TD
              swmmrs.objects.ControlRule[ControlRule]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.ControlRule
                


              click swmmrs.objects.ControlRule href "" "swmmrs.objects.ControlRule"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound control-rule definition.

Curve 


              flowchart TD
              swmmrs.objects.Curve[Curve]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.Curve
                


              click swmmrs.objects.Curve href "" "swmmrs.objects.Curve"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound curve definition.

CustomShape 


              flowchart TD
              swmmrs.objects.CustomShape[CustomShape]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.CustomShape
                


              click swmmrs.objects.CustomShape href "" "swmmrs.objects.CustomShape"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound custom-shape definition.

LandUse 


              flowchart TD
              swmmrs.objects.LandUse[LandUse]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.LandUse
                


              click swmmrs.objects.LandUse href "" "swmmrs.objects.LandUse"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound land-use definition.

Pollutant 


              flowchart TD
              swmmrs.objects.Pollutant[Pollutant]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.Pollutant
                


              click swmmrs.objects.Pollutant href "" "swmmrs.objects.Pollutant"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound pollutant definition.

SnowmeltParameterSet 


              flowchart TD
              swmmrs.objects.SnowmeltParameterSet[SnowmeltParameterSet]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.SnowmeltParameterSet
                


              click swmmrs.objects.SnowmeltParameterSet href "" "swmmrs.objects.SnowmeltParameterSet"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound editable snowmelt parameter-set definition.

METHOD DESCRIPTION
update

Atomically update supplied root snowmelt fields in project units.
ATTRIBUTE DESCRIPTION
impervious

Return the fixed impervious-surface Live View.

TYPE: SnowmeltSurface

pervious

Return the fixed pervious-surface Live View.

TYPE: SnowmeltSurface

plow_depth

Return the snow depth at which plowing begins in project units.

TYPE: float

plowable

Return the fixed plowable-surface Live View.

TYPE: SnowmeltSurface

plowable_fraction

Return the fraction of impervious area that is plowable.

TYPE: float

removal_fractions

Return fractions routed to five plowed-snow destinations.

TYPE: tuple[float, float, float, float, float]

removal_subcatchment

Return the optional subcatchment receiving removed snow.

TYPE: Subcatchment | None

impervious property 

impervious: SnowmeltSurface

Return the fixed impervious-surface Live View.

pervious property 

pervious: SnowmeltSurface

Return the fixed pervious-surface Live View.

plow_depth property writable 

plow_depth: float

Return the snow depth at which plowing begins in project units.

plowable property 

plowable: SnowmeltSurface

Return the fixed plowable-surface Live View.

plowable_fraction property writable 

plowable_fraction: float

Return the fraction of impervious area that is plowable.

removal_fractions property writable 

removal_fractions: tuple[float, float, float, float, float]

Return fractions routed to five plowed-snow destinations.

removal_subcatchment property writable 

removal_subcatchment: Subcatchment | None

Return the optional subcatchment receiving removed snow.

update 

update(**changes: object) -> None

Atomically update supplied root snowmelt fields in project units.

SnowmeltSurface

Expose one fixed snowmelt surface as a live project-unit view.

METHOD DESCRIPTION
update

Atomically update supplied surface fields in project units.
ATTRIBUTE DESCRIPTION
base_temperature

Return the base temperature in project temperature units.

TYPE: float

free_water_fraction

Return the snowpack free-water fraction.

TYPE: float

initial_free_water

Return the initial free-water depth in project rain-depth units.

TYPE: float

initial_snow_depth

Return the initial snow depth in project rain-depth units.

TYPE: float

maximum_melt_coefficient

Return the maximum melt coefficient in project snowmelt units.

TYPE: float

minimum_melt_coefficient

Return the minimum melt coefficient in project snowmelt units.

TYPE: float

snow_depth_for_full_coverage

Return the snow depth for complete areal coverage.

TYPE: float

base_temperature property writable 

base_temperature: float

Return the base temperature in project temperature units.

free_water_fraction property writable 

free_water_fraction: float

Return the snowpack free-water fraction.

initial_free_water property writable 

initial_free_water: float

Return the initial free-water depth in project rain-depth units.

initial_snow_depth property writable 

initial_snow_depth: float

Return the initial snow depth in project rain-depth units.

maximum_melt_coefficient property writable 

maximum_melt_coefficient: float

Return the maximum melt coefficient in project snowmelt units.

minimum_melt_coefficient property writable 

minimum_melt_coefficient: float

Return the minimum melt coefficient in project snowmelt units.

snow_depth_for_full_coverage property writable 

snow_depth_for_full_coverage: float

Return the snow depth for complete areal coverage.

update 

update(**changes: object) -> None

Atomically update supplied surface fields in project units.

Street 


              flowchart TD
              swmmrs.objects.Street[Street]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.Street
                


              click swmmrs.objects.Street href "" "swmmrs.objects.Street"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound street definition.

TimePattern 


              flowchart TD
              swmmrs.objects.TimePattern[TimePattern]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.TimePattern
                


              click swmmrs.objects.TimePattern href "" "swmmrs.objects.TimePattern"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound time-pattern definition.

Transect 


              flowchart TD
              swmmrs.objects.Transect[Transect]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.Transect
                


              click swmmrs.objects.Transect href "" "swmmrs.objects.Transect"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound transect definition.

InletDesign 


              flowchart TD
              swmmrs.objects.InletDesign[InletDesign]
              swmmrs.objects._base._LiveView[_LiveView]

                              swmmrs.objects._base._LiveView --> swmmrs.objects.InletDesign
                


              click swmmrs.objects.InletDesign href "" "swmmrs.objects.InletDesign"
              click swmmrs.objects._base._LiveView href "" "swmmrs.objects._base._LiveView"

Expose a generation-bound inlet-design definition.