Book Review: QGIS for Hydrological Applications, Second Edition
This recently published second edition provides recipes for catchment hydrology and water management, and introduces new QGIS plugins, features and datasets that greatly improve the workflow and user experience. Here is my brief review of the book and a few of my thoughts on how well it meets its objectives.
Content and background
This book started from different course materials and training videos using open source GIS. The book provides a series of recipes for catchment hydrology and water management, in the form of QGIS tutorials using version 3.22 and higher. In a series of projects (divided into seven chapters with a total of 181 pages), readers will learn the following topics:
- prepare data from hard copy maps
- import tabular data into QGIS
- perform spatial analysis with map algebra
- perform stream and catchment delineation
- add open data to a catchment
- calculate percentages of land cover per subcatchment
- design a map
Each chapter starts with an introduction of the problem, learning objectives and a general workflow depicting which actions need to be taken and in which order to solve the problem. Each subparagraph covers a part of the workflow with instructions for the user on how to use QGIS to manipulate data, learn new functionality and solve a spatial problem.
The book is designed for professionals in hydrology and water management, especially those involved in using simulation models for water management and performing GIS analysis. However, it is also suitable for beginners in QGIS who want to learn GIS concepts and QGIS features in a problem based manner. The book can be used with an instructor in the classroom, as well as an independent study for beginners and experts.
The book was written by Hans van der Kwast and Kurt Menke. Hans van der Kwast is a senior lecturer at IHE Delft; Kurt Menke is a spatial analyst, cartographer, web map developer, trainer/teacher, and author working with Septima.
What’s new in the second edition
The second edition does not replace but enhances the first published edition of the book (2019). There are a number of updates regarding the analysis tools that are covered in the second edition. For example, the chapter about stream and catchment delineation has been updated and now offers an alternative way of doing the same, with a different set of tools. Where the first edition used a workflow using SAGA (System for Automated Geoscientific Analyses) and tools from the processing toolbox, that has been replaced with tools from the PCRaster plugin. This powerful package of software for map algebra and environmental dynamic modeling has now been released as an official QGIS plugin and has been downloaded more than 6,000 times.
Another change is the inclusion of raster attribute tables, a new feature in QGIS which allows users to display and edit Raster Attribute Tables (RATs) for discrete rasters using paletted/unique-values renderer. RATs open up a set of use cases, such linking layer styling panel styles to an attribute table where extra attributes can be added.
The second edition includes more open datasets that can be added to QGIS. The fifth chapter from the first edition included the CORINE land cover map as a WMS service, but has been replaced with the ESA WorldCover dataset, a global land cover map for 2020 at 10m resolution that can be added as a WMTS layer in QGIS. Additionally, there are smaller changes on all kinds of functionality in QGIS that improve the workflow and user experience.
With regards to styling and print layout, there are also a number of updates. There’s a lot of symbology: for every set of analysis steps, the authors show you how to style the data beautifully on the map. All the latest renderers are used, such as new ways of styling multiple classes of streams. The print layout incorporates legend patch shapes into the legend, which is a new feature that enables users to download legend patch shapes provided by the QGIS community, or base a legend patch shape on the features of their data. Finally, a new gradient legend option for rasters for a print layout has also been incorporated in the book, among other things.
In the launch webinar accompanying the release of this book, author Hans van der Kwast states that this book offers a good experience for someone who is not a hydrologist. The term “hydrological applications” in the title should not intimidate anyone, as it’s just one way to learn all the great new QGIS functionality.
This statement very well summarizes the approach of the authors as well as how users should approach it: hydrology is the theme that ties together new QGIS functionality that can be applied to many other themes. If you are a QGIS user without a hydrological background, you are likely to pick many different new approaches, tools, datasets and concepts that will improve your current QGIS skills.
One very helpful decision with this is the inclusion of freely available video material. Each chapter comes with a video link that includes additional material where concepts are explained that are not found in the book. Experienced QGIS users will probably know most of these concepts, but new users will benefit greatly from it. The video content is also very helpful when you need to interact with the map canvas, such as the first chapter where you need to use GCPs from a grid. Having someone guide you through this procedure with a video is much better using a video than through written material. I have to add that the videos follow the book materials closely. And although they are mostly very short, they contain a lot of information, meaning very much to-the-point.
Another great point of the book is the sequencing of the materials found in the different chapters: the book starts with three projects containing basic QGIS skills, before tackling a long project spread out over multiple chapters. These contain more complex tasks involving different intermediary files that are required to solve the problem stated in the introduction of the chapter.
If you want to learn more about using raster data with QGIS, this is a great book. You will learn a lot about manipulating raster data, combining it with other rasters or additional data sources. I was especially impressed with chapter 4, which covers stream and catchment delineation. It is really a masterclass on choosing different raster tools, data formats and using the right tool parameters to get the required results to solve a problem. External plugins such as PCRaster will enhance the existing QGIS functionality greatly, which is another reason to read this book. The same goes for plugins that will help you style and edit maps in a better and more productive way.
By following the different steps presented in each chapter, you will notice that the authors are very consequent in what they do and how. For example, they style new layers directly after creating them, often applying existing styling to save time and effort. They also share productivity hacks, such as adding a favorites file folder so you always have quick access to your files instead of having to navigate to them from inside QGIS, which can be a rather time-consuming exercise. You will also learn a great deal about naming conventions for new files, and why safety copies are always made in case something goes wrong.
The approach, presentation and great content make this book a great reference for both beginners and experienced QGIS users who want to learn new functionality, be more productive and creative.