---
title: "Ground elevation grid | Technical Reference"
slug: "ground-elevation-grid"
description: "Read an introduction to the ground elevation grid."
tags: ["2D modelling"]
updated: 2024-11-07T10:25:31Z
published: 2024-11-07T10:25:31Z
canonical: "help.floodmodeller.com/ground-elevation-grid"
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.

# Ground elevation grid

A Flood Modeller 2D simulation requires the ground elevation data.

These data are used to determine the path water will take across the floodplain. This is often a Digital Terrain Model (DTM) or Digital Elevation Model (DEM).

The tool now accepts the following formats for topography data:

* ASCII Grid (ASC)
* GeoTIFF (TIF)
* Binary Grid (FLT)
* ESRI Shapefile (SHP)

Note that shapefiles are primarily used to apply additional changes to an existing grid. To use a shapefile to define the entire topography of a model then it would need to be a grid made up of a collection of polygons (i.e. one polygon for each grid square). The solver can accept polylineZ and polygonZ format shapefiles. It uses the following hierarchy: If a shapefile has an attribute table with a populated field entitled "height" or "height1", then these elevation data will always supersede the embedded Z values of the polylineZ/polygonZ.