Water quality (landuse, buildup, washoff, treatment)#

Note

Engine: OpenSWMM 6 — refactored.

solver.quality configures landuses and their pollutant buildup/washoff functions, plus node-level treatment expressions.

Reference: openswmm_quality.h.

Quickstart#

from openswmm.engine import Solver, BuildupFunc, WashoffFunc

with Solver("model.inp") as s:
    s.quality.landuses.add("RESIDENTIAL")

    s.quality.set_buildup(
        "RESIDENTIAL", "TSS",
        func=BuildupFunc.POW, c1=10.0, c2=0.1, c3=2.0)
    info = s.quality.get_buildup("RESIDENTIAL", "TSS")
    print(info["func"], info["c1"])

    s.quality.set_washoff(
        "RESIDENTIAL", "TSS",
        func=WashoffFunc.EXP, coeff=0.5, expon=2.0)

    # Per-node treatment expression.
    s.quality.set_treatment("J1", "TSS", "R = 0.5*C")

Landuses sub-collection#

lu = s.quality.landuses["RESIDENTIAL"]
lu.sweep_interval = 7.0       # days
lu.sweep_removal = 0.6

for lu in s.quality.landuses:
    print(lu.id, lu.sweep_interval)

s.quality.landuses.add("COMMERCIAL")

solver.quality.landuses is indexable by int | str and iterable; items are Landuse wrappers with typed properties.

Buildup / washoff#

Both APIs accept int | str for the landuse and pollutant selectors. The function-type argument is an enum (BuildupFunc / WashoffFunc) — passing an integer still works.

set_buildup(landuse, pollutant, *, func, c1, c2, c3, normalizer=0) get_buildup(landuse, pollutant) -> Dict[str, ...] returns {"func": BuildupFunc, "c1": float, "c2": float, "c3": float, "normalizer": int}.

set_washoff(landuse, pollutant, *, func, coeff, expon, sweep_effic=0.0, bmp_effic=0.0) get_washoff(landuse, pollutant) -> Dict[str, ...] returns {"func": WashoffFunc, "coeff": float, "expon": float, "sweep_effic": float, "bmp_effic": float}.

Treatment#

s.quality.set_treatment("J1", "TSS", "R = 0.5*C")
print(s.quality.get_treatment("J1", "TSS"))
s.quality.clear_treatment("J1", "TSS")

Treatment expressions follow SWMM’s standard syntax (see the SWMM 5 reference manual).