Using Web GIS to Make Your Spatial Data Special
By Justin Kirtz (Posted July 20, 2021)
Modern Geographic Information Systems (GIS) offer a wide range of tools and useful features that expand upon the simple cartographic functions of the past. No longer just a tool to create hardcopy maps, GIS solutions can provide deep insight into data, advanced data visualization, direct data editing, and more. They are also scalable and flexible enough to benefit nearly any project size — from a small value-added deliverable to an entire complex GIS ecosystem. Here are just a few ways that web GIS can expand on traditional hardcopy maps and desktop GIS.
Dive Into Data
One of the defining characteristics of a GIS is the ability to tie the feature’s geometry on a map to a database that houses feature-specific data and information. This gives the user a visual representation of the feature such as a groundwater monitoring well, a river, or a parcel of land. The user is also given the ability to query and use the underlying data stored in a database. One of the benefits of web GIS is the ability for the user to dynamically draw on the map to select features to query. After the query has executed, the returned data can be displayed in a variety of formats including tables, graphs, charts, and pivot tables. Numerical data can be processed with aggregate statistics such as sum, minimum/maximum, and standard deviation, for a deeper dive into the data.
For example, consider a parcel of land that is being monitored for groundwater contamination via groundwater monitoring wells. Wells may be sampled four times a year for groundwater, with the benzene results recorded and stored for each sampling event in a database. The user can then dynamically draw on the map to query a group of wells, return the average benzene result for the selected group of wells for each sampling event, and then plot each average benzene result on a line graph contained directly in the web GIS app. The resulting graph will show the change in average benzene concentrations for the selected wells over time. The benzene results can also be displayed via a table, allowing for even more advanced options such as filtering, sorting, group aggregate statistics, exporting to a spreadsheet, and more.
Animating Trends Over Time
Visually showing how data changes over time is a powerful way to bring data to life. While it is certainly possible to demonstrate how data changes over time in a spreadsheet, it is often useful to see that change happen visually because it provides a better spatial context for that change. One way to do this is via a time slider, a simple web GIS tool that uses a Date field to display the layer’s features sequentially. As the tool sequentially steps through each feature in the layer, it groups features by a unique date in the Date field. It will only display the group of features that match the current date. Each group of features will display for a few seconds before the tool proceeds to the next date and displays that group of features in the data set, which results in a looping animation. The time slider can display data in two ways: cumulative or unique. When displaying data cumulatively, the time slider will start from the earliest date in the data set and gradually add more features to the display, illustrating how data has accumulated over time. When displaying data uniquely, the time slider will only show the features that match the current unique date.
Let’s return to the example of sampling groundwater for benzene concentrations. After groundwater monitoring activities have been occurring on the parcel for several years, it may be useful to see how the groundwater plume of benzene has changed over time on a quarter by quarter basis. A groundwater plume polygon can be drawn around groups of wells with an elevated level of benzene for each quarterly sampling event. Each plume polygon will be given a sample date field that contains the date of the sampling event. As the time slider sequentially steps through each sampling event date, it displays the appropriate groundwater benzene plume polygon, thus animating the groundwater plume as it changes over time.
There are often situations in which spatial data serves as a supplement to a larger narrative being told. There may not be a need for a fully-featured GIS application but rather a few small interactive web maps. A StoryMap is a web application that combines text, web GIS maps, and other multimedia to create seamless and interactive narratives. Harnessing the power of web GIS, StoryMaps give static information a stronger sense of place, illustrate spatial relationships, and present a visually appealing interface for the end user. StoryMaps are accessible over the web, just like the web GIS application, and are perfect for presentations, electronic deliverables, reports, and more.
The advent of web GIS has completely changed the GIS industry. It empowers users to view, process, and analyze their data without needing a powerful desktop computer or expensive GIS software. It also allows users to take their data with them in the field via their smart device. SynTerra will be at the forefront to help clients achieve their spatial data needs as web GIS continues to grow and evolve.
Click here to learn more about SynTerra’s web GIS capabilities.