---
title: "Add a Flow-Time boundary to a 1D river network"
slug: "add-flow-time-boundary"
description: "Learn how to add a Flow-Time boundary to a 1D river network."
tags: ["1D river modelling", "hydrology", "boundary conditions"]
updated: 2026-03-09T11:13:43Z
published: 2026-03-09T11:13:43Z
canonical: "help.floodmodeller.com/add-flow-time-boundary"
stale: true
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.floodmodeller.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Add a Flow-Time boundary to a 1D river network

Note: to follow this guide, a river network must be loaded and active. You must therefore initially [Start a new river network](/v1/docs/how-to-start-a-new-1d-river-network) or [Load a river network](/v1/docs/how-to-load-a-network).

To add a Flow-Time or a hydrological boundary node to your river network, follow the steps below:

In the **1D River Network** tab, select a row in the network table. Your boundary node will be added below this selected row, so it is likely you will want to select the top row (named **General**) for the boundary to be the first node in your network.

**Note:** Boundary nodes can be located out of position, all together at either end of a network. The labels specifying connecting nodes will determine the true position of the node both when it is drawn with links on your map and when you run a simulation with your network.

Select which boundary node you wish to add. These can be selected from the **1D River Build** tab, where they are listed as types of flow boundary node.

![1DRiverimageshydrographs.gif](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/1DRiverimageshydrographs.gif)

After selecting a node type, hover your cursor over the map and you will notice it shows the icon of your selected node. Click on the map at the desired node location to add the new node.

After adding a boundary node you will be prompted to provide a node label:

![1DRiverimagesbdynodelabel.jpg](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/1DRiverimagesbdynodelabel.jpg)

The label you select should also be shared by the hydraulic node (e.g. River Section node) receiving the inflow from the boundary node. After defining a label, click **OK** and the node will be added to the network table, nodes list table and map simultaneously.

Your boundary node has been successfully added to your network!

When you save your network, the nodes sharing the same name will then be shown connected.

It is also possible to add hydrology nodes to your network using the menu accessed by right-clicking on the Network table. First highlight the node upstream from your new node, then select Insert > New unit from this menu. A new window will be displayed enabling you to select any node type including hydrology boundaries. You will then be prompted to provide the necessary node labels as described above.

## Related topics

More about [River Boundary Nodes](/v1/docs/river-boundaries-overview)