Network Elements Reference

pywmp.network provides the basin model element classes that compose multi-subbasin simulation networks. Elements are wired together in a BasinModel (via pywmp.workflow.DesignStormSimulation or directly through pywmp.simulation.engine.BasinModel).

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pywmp.network

from pywmp.network import (
    SubbasinElement,
    ReachElement,
    JunctionElement,
    ReservoirElement,
    DiversionElement,
    ROMElement,
)

Class	HEC-HMS equivalent	Purpose
SubbasinElement	Subbasin	Loss + transform + baseflow → runoff
ReachElement	Reach	Channel routing (Muskingum, lag, …)
JunctionElement	Junction	Sum flows from multiple upstream elements
ReservoirElement	Reservoir	Storage routing via LevelPoolReservoir
DiversionElement	Diversion	Split flow by fraction or fixed rate
ROMElement	—	Wraps a 2D ROMSimulation as a network node

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SubbasinElement

class SubbasinElement(
    name, loss_model, transform_model,
    baseflow_model=None, units='USC'
)

Assembles a complete subbasin by composing any compatible loss, transform, and optional baseflow model.

Parameter	Type	Description
name	str	Element identifier
loss_model	object	Any object with .compute(precip) → (effective, loss)
transform_model	object	Any object with .compute(effective) → TimeSeries
baseflow_model	object | None	Optional; .compute(times[, recharge]) → TimeSeries

Methods

SubbasinElement.run(rainfall: TimeSeries) -> TimeSeries   # total runoff

Example

from pywmp.network import SubbasinElement
from pywmp.losses import SCSCurveLoss
from pywmp.transform import SCSUnitHydrograph
from pywmp.baseflow import RecessionBaseflow

sb = SubbasinElement(
    name="B1",
    loss_model=SCSCurveLoss(CN=78, area_mi2=2.5),
    transform_model=SCSUnitHydrograph(lag_hr=1.2, area_mi2=2.5),
    baseflow_model=RecessionBaseflow(Q0=3.0, recession_k=0.9),
)
runoff_ts = sb.run(precip_ts)

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ReachElement

class ReachElement(name, routing_model, units='USC')

Routes flow through a channel reach using any routing model.

Parameter	Type	Description
name	str	Element identifier
routing_model	object	Any object with .compute(inflow) → TimeSeries

from pywmp.network import ReachElement
from pywmp.routing import MuskingumRouting

reach = ReachElement("R1", MuskingumRouting(K_hr=0.8, x=0.2))
routed = reach.run(upstream_flow_ts)

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JunctionElement

class JunctionElement(name, units='USC')

Sums two or more upstream flow TimeSeries at a confluence point.

from pywmp.network import JunctionElement

j = JunctionElement("Outlet")
total = j.run([flow_b1, flow_b2, routed_r1])

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ReservoirElement

class ReservoirElement(name, reservoir_model, units='USC')

Wraps a LevelPoolReservoir as a network node.

from pywmp.network import ReservoirElement
from pywmp.reservoir import LevelPoolReservoir

res_elem = ReservoirElement("Pond1", LevelPoolReservoir(elev, stor, outlets))
outflow, elev_ts = res_elem.run(inflow_ts)

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DiversionElement

class DiversionElement(name, fraction=None, fixed_rate=None, units='USC')

Splits inflow into a diverted portion and a main-channel continuation. Supply either fraction (0–1) or fixed_rate (cfs or m³/s).

from pywmp.network import DiversionElement

div = DiversionElement("Div1", fraction=0.30)   # 30 % diverted
main_flow, diverted_flow = div.run(inflow_ts)

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ROMElement

class ROMElement(name, rom_simulation, units='USC')

Embeds a ROMSimulation (2D shallow-water) as a node in a 1D basin network. Inflow from upstream elements is applied as a boundary condition to the 2D domain; the outlet hydrograph is returned as the element output.

from pywmp.network import ROMElement
from pywmp.rom import ROMSimulation

rom_elem = ROMElement("ROM_Cell_1", rom_sim)
outlet_ts = rom_elem.run(inflow_ts)