---
title: "Hazard Mapping | Technical Reference"
slug: "hazard-mapping"
description: "Learn about hazard mapping and how it is calculated. "
tags: ["2D modelling"]
updated: 2022-07-29T10:22:55Z
published: 2022-07-29T10:22:55Z
canonical: "help.floodmodeller.com/hazard-mapping"
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.

# Hazard Mapping

2D solver can output hazard rating as described in Assessing and Valuing the Risk to Life from Flooding for Use in Appraisal of Risk Management Measures (DEFRA, May 2008).

Hazard is calculated using the following formula:

HR = d x (v + 0.5) + DF

Where:

HR = Hazard rating

d = Depth

v = Velocity

DF = Debris factor

The debris factor can be set to a static value by the user, or can be calculated automatically during the simulation based upon depth, velocity and land use.

To enable hazard mapping output, include "Hazard" in the list of 2D output variables.

<output_results>

<output output_id="" format="SMS9">

<variables>

Depth

Velocity

Hazard

</variables>

<frequency>300</frequency>

</output>

<massfile frequency="10">Dam_ADI_MB.csv</massfile>

<check>true</check>

</output_results>

By default, 2D solver will use a static debris factor of 1.0

To specify a debris factor, include the <hazard_debris_factor_method> tag. The following XML snippet shows outputs configured to produce hazard mapping using a fixed debris factor of 0.5

<output_results>

<hazard_debris_factor_method>

<static factor="0.5"/>

</hazard_debris_factor_method>

<output output_id="" format="SMS9">

<variables>

Depth

Velocity

Hazard

</variables>

<frequency>300</frequency>

</output>

<massfile frequency="10">Dam_ADI_MB.csv</massfile>

<check>true</check>

</output_results>

To specify a varying debris factor, use the "varying" tag to specify the land use type:

<output_results>

<hazard_debris_factor_method>

<varying land_use="pasture"/>

</hazard_debris_factor_method>

<output output_id="" format="SMS9">

<variables>

Depth

Velocity

Hazard

</variables>

<frequency>300</frequency>

</output>

<massfile frequency="10">Dam_ADI_MB.csv</massfile>

<check>true</check>

</output_results>

Possible values of land use type are:

pasture

woodland

urban

conservative