---
title: "Hard Bed Option | Sediment Transport"
slug: "hard-bed-option"
description: "Learn about the hard bed option and data block, and its parameters. "
tags: ["1D river modelling"]
updated: 2022-11-01T15:43:17Z
published: 2022-11-01T15:43:17Z
canonical: "help.floodmodeller.com/hard-bed-option"
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.

# Hard Bed Option

The hard bed option will prevent erosion from occurring below the initial bed elevation in the designated sections. If required, a HARD BED data block can be specified in any location after the General System Parameters within the sediment module datafile.

Note that where a hard bed prevents erosion, it will also prevent an armour layer forming when the SORTED algorithm is selected in the General System Parameters at the top of the datafile.

If method 2 or 3 is selected for updating the bed, then the channel shape may change. The hard bed option will then prevent erosion below the original elevation at the minimum bed level at the section, but erosion of the banks may occur. An example of the structure of this section of the file is shown in Figure 7.

## Datafile Format - Hard Bed Option

Line 1 keyword 'HARD BED'

Line 2 n1

Line 2 labeli

where

n1= number of ensuing node labels

labeli= node labels of hard bed sections