Interpolating a surface and determining overland flow distance via qGIS and SAGA GIS

Purpose

The purpose of this wiki is to introduce users to the cross functionality of open source software. It is intended to show how a user can take raw elevation data and create a usable GIS product within a short time period, as to realize geographic phenomena in real world situations such as a spill mitigation scenario.

Introduction

The direction of this project is to show how free and open source software for geospatial applications (FOSS4G) can be implemented as an alternative and in some cases an enhancement to licensed products such as IDRISI and ESRI's ArcMap. To portray this both qGIS and SAGA GIS will be used. The purpose for using two programs is due to ease of use. Where qGIS allows for easy operations to be performed in a somewhat familiar GUI, it does not account for more in depth applications such as flow direction of liquids and the distance they must travel before entering a major tributary. Thus, this tutorial aims to show how to take vector elevation data and transform it to a raster surface which is conducive to modelling and extrapolation.

Software Download and Data Gathering

To download the necessary programs for the purpose of this tutorial, click the following link for the qGIS download portal[1], as well as this link for SAGA GIS's download portal[2]. Upon downloading and installing the correct version as it corresponds to your computer, the next step is to find suitable data for analyzing the area of study. Among many sources, elevation data for Canadian areas can be found easily through such outlets as GeoBase at the following link [3] or GeoGratis at this link [4].

Methods

What I did

Surface Interpolation in qGIS

How to do part 1

Determining Overland Flow Distance in SAGA GIS

How to do part 2

Conclusions

What was the result