# FlowBoundary

A FlowBoundary adds water to the model at a specified flow rate. It can be used as a boundary condition like a measured upstream flow rate, or lateral inflow.

# 1 Tables

## 1.1 Static

We require that the edge connecting the FlowBoundary to the Basin should point towards the Basin, so that positive flow corresponds to water being added to the model. The set flow rate will be pumped unless the intake storage (for a negative flow rate) is less than \(10~\text{ m}^3\), in which case the flow rate will be linearly reduced to \(0~\text{ m}^3/s\). Note that the connected node must always be a Basin.

column | type | unit | restriction |
---|---|---|---|

node_id | Int32 | - | sorted |

active | Bool | - | (optional, default true) |

flow_rate | Float64 | \(\text{m}^3/\text{s}\) | non-negative |

## 1.2 Time

This table is the transient form of the `FlowBoundary`

table. The only differences are that a time column is added and the nodes are assumed to be active so this column is removed. The table must by sorted by time, and per time it must be sorted by `node_id`

. With this the flow rates can be updated over time. In between the given times the flow rate is interpolated linearly, and outside the flow rate is constant given by the nearest time value. Note that a `node_id`

can be either in this table or in the static one, but not both.

column | type | unit | restriction |
---|---|---|---|

node_id | Int32 | - | sorted |

time | DateTime | - | sorted per node_id |

flow_rate | Float64 | \(\text{m}^3/\text{s}\) | non-negative |

## 1.3 Concentration

This table defines the concentration of substances for the flow from the FlowBoundary.

column | type | unit | restriction |
---|---|---|---|

node_id | Int32 | - | sorted |

time | DateTime | - | sorted per node_id |

substance | String | - | can correspond to known Delwaq substances |

concentration | Float64 | \(\text{g}/\text{m}^3\) |

# 2 Equations

A FlowBoundary can be connected directly to a Basin and prescribes the flow to that Basin. Since the `flow_rate`

cannot be negative a FlowBoundary can only add water to the model.