Infrastructure (transects, streets, inlets, LIDs)#

Note

Engine: OpenSWMM 6 — refactored. Documents openswmm.engine.Infrastructure.

The Infrastructure class consolidates the SWMM features that configure complex hydraulic infrastructure:

Transects — irregular channel cross-sections ([TRANSECTS]).
Streets — HEC-22 street geometry for inlet capture ([STREETS]).
Inlets — grate / curb / slot inlets and their capacity curves ([INLETS] / [INLET_USAGE]).
LIDs — Low-Impact Development controls ([LID_CONTROLS] / [LID_USAGE]): bio-retention, infiltration trench, porous pavement, rain gardens, green roofs, swales.

Reference: openswmm_infrastructure.h.

Class signature#

class Infrastructure:
    def __init__(self, solver: Solver) -> None: ...

Key methods#

Transects#

Method	Action
`transect_count()`	Number of registered transects.
`transect_set_roughness(idx, ...)()`	Manning’s n for left bank / channel / right bank.
`transect_add_station(idx, x, elev)()`	Append a station-elevation point.

Streets#

Method	Action
`street_count()`	Number of registered street geometries.
`street_set_params(idx, ...)()`	Width, slopes, depressions, manning, sidewalk geometry.

Inlets#

Method	Action
`inlet_count()`	Number of registered inlets.
`inlet_set_params(idx, ...)()`	Inlet type, geometry, capacity curve, clogging.

LID controls (definitions)#

Method	Action
`lid_count()`	Number of registered LID controls.
`lid_set_surface(idx, ...)()`	Surface layer (storage depth, roughness, slope).
`lid_set_soil(idx, ...)()`	Soil layer (thickness, porosity, conductivity, …).
`lid_set_storage(idx, ...)()`	Storage layer (gravel thickness, void ratio, …).
`lid_set_drain(idx, ...)()`	Underdrain (offset, coefficient, exponent, delay).

LID usage (apply LID to a subcatchment)#

Method	Action
`lid_usage_add(sc_idx, lid_idx, ...)()`	Attach an LID to a subcatchment with area, # units, % impervious treated, and drainage routing.

End-to-end example#

from openswmm.engine import Solver, Infrastructure, Subcatchments

with Solver("urban_streets.inp", "urb.rpt", "urb.out") as s:
    infra = Infrastructure(s)
    sc = Subcatchments(s)

    print(
        f"transects={infra.transect_count()}  "
        f"streets={infra.street_count()}  "
        f"inlets={infra.inlet_count()}  "
        f"lid_controls={infra.lid_count()}"
    )

    # During edit phase: add a bio-retention LID on subcatchment S1
    s.open()
    infra.lid_usage_add(
        sc_idx=sc.get_index("S1"),
        lid_idx=0,                       # first LID control
        number=10,
        area=200.0,
        width=20.0,
        init_sat=0.0,
        from_impervious=50.0,            # treats 50% of impervious area
        to_pervious=False,
        drain_subcatch_idx=-1,
        drain_node_idx=-1,
        full_coverage=False,
        from_pervious=0.0,
    )
    s.initialize()
    s.start()
    while s.step():
        pass
    s.end()

Common recipes#

Configure a bio-retention LID control#

# Layer parameters for "BIO_RETENTION_1" (LID control index 0)
infra.lid_set_surface(idx=0, depth=6.0, vol_frac=0.0,
                      roughness=0.1, slope=0.0)
infra.lid_set_soil(idx=0, thickness=18.0, porosity=0.5,
                   fcap=0.2, wp=0.05, conductivity=0.5,
                   slope=10.0, suction=3.5)
infra.lid_set_storage(idx=0, thickness=12.0, void_ratio=0.75,
                      k_seepage=0.5, clog_factor=0.0)
infra.lid_set_drain(idx=0, coeff=1.0, exponent=0.5,
                    offset=6.0, delay=6.0,
                    h_open=0.0, h_close=0.0)

Apply an LID to multiple subcatchments#

for sc_id in ["S1", "S3", "S5"]:
    infra.lid_usage_add(
        sc_idx=sc.get_index(sc_id),
        lid_idx=0,
        number=4,
        area=100.0,
        width=10.0,
        init_sat=0.0,
        from_impervious=30.0,
        to_pervious=False,
        drain_subcatch_idx=-1,
        drain_node_idx=-1,
        full_coverage=False,
        from_pervious=0.0,
    )

Add a transect with three stations#

# Trapezoidal channel: deeper in the middle
t = 0
infra.transect_set_roughness(t, n_left=0.05, n_channel=0.030, n_right=0.05)
infra.transect_add_station(t, x=0.0,  elev=10.0)
infra.transect_add_station(t, x=10.0, elev=7.0)
infra.transect_add_station(t, x=20.0, elev=10.0)

Configure a curb-opening street inlet#

infra.inlet_set_params(
    idx=0,
    inlet_type=int(InletType.CURB),
    height=0.5,                   # opening height
    length=10.0,
    # ... per-type parameters ...
)

EngineState requirements & exceptions#

Method group	Required state	Notes
all setters	`OPENED`	Apply before `initialize()` to take effect on the run.
count accessors	`OPENED` or later	n/a

Common EngineError codes:

INVALID_INDEX — out-of-range transect / street / inlet / LID index.
INVALID_TYPE — wrong layer setter for the LID kind, etc.