Referencing Model Results¶

Overview¶

Model results (reflecting the system state) can be referenced within dynamic expressions in other parts of the model using the node.* namespace.

Reference Syntax¶

Node outputs follow this pattern:

node.<node_name>.<output_variable>

Example: A node named catchment with output dsflow:

node.catchment.dsflow

‘This’ Syntax¶

When referring to outputs of the current node, the ‘this’ syntax offers can be more convenient than giving the fully qualified name every time:

Example: An unregulated user may have a pump-capacity which is a function of its own upstream flow, this.uflow:

pump = if(this.usflow > 100, 10, 0)

Common Output Variables¶

All node outputs are accessible in this way. Some common ones are:

Variable	Description
`usflow`	Upstream flow (flow entering the node)
`dsflow`	Downstream flow (flow leaving the node)
`ds_1`	Downstream flow on link 1 (alias for dsflow)
`inflow`	Inflow to the node
`volume`	Storage volume
`loss`	Losses (e.g., seepage, evaporation)

Using Node References¶

Reference another node’s output in any dynamic expression:

[node.catchment]
loc = 0, 0
type = gr4j
rain = data.climate_csv.by_name.rainfall
evap = data.climate_csv.by_name.evap

[node.other_catchment]
loc = 0, 10
type = inflow
inflow = node.catchment.dsflow

[node.user]
loc = 0, 20
type = user
demand = 0.1 * node.other_catchment.inflow

Temporal Offset for Node Outputs¶

You can access previous timestep values using offset syntax:

node.<name>.<output>[offset, default_value]

Important: Only negative offsets (past values) are supported for node references. Forward lookups are not allowed because future values haven’t been computed yet.

Examples:

; Yesterday's downstream flow (default to 0 if at simulation start)
node.catchment.dsflow[-1, 0.0]

; Storage volume from 7 days ago
node.reservoir.volume[-7, 1000.0]

; Calculate daily change in storage
node.reservoir.volume - node.reservoir.volume[-1, 0.0]

; Conditional based on previous flow
if(node.catchment.dsflow > node.catchment.dsflow[-1, 0.0], 1, 0)

Name Handling¶

Node names follow the same sanitisation rules as data references:

Names are case-insensitive
Special characters are replaced with underscores
References are converted to lowercase internally

So node.My_Catchment.dsflow and node.my_catchment.dsflow are equivalent.