Overview

The GGST app uses GRACE data to generate time series and animated maps of groundwater storage changes. GRACE provides monthly estimates of water storage anomalies in equivalent water height and has provided monthly gravity field solutions since April 2002. Estimates of mass variability and associated observational errors are available on a global 300 km grid. GRACE has proved an effective tool for characterizing groundwater storage changes in large regions (J. Famiglietti et al., 2011; J. S. Famiglietti, 2014; Rodell, Velicogna, & Famiglietti, 2009; Thomas, Reager, Famiglietti, & Rodell, 2014).

While several tools have been developed for processing and visualizing GRACE data, GGST is designed specifically to support groundwater resource management by regional stakeholders and decision-makers. We accomplish this by carefully processing the raw GRACE data to remove anomalies and improve resolution. This is done by separating the groundwater component from the other water storage components using GLDAS, subsetting the data to specific regions of interest, and by presenting the results in a simple, intuitive interface. The algorithm we use to process the GRACE and GLDAS data to produce groundwater anomalies on both a global and regional scale is described in detail on the Algorithm page.

You can access GGST using the Tethys Web Application or by using the API and the associated Google Colaboratory Notebook that makes the API intuitive to use. A brief introduction to these two methods is provided below.

GGST Web Application

The GGST web application was built using Tethys Platform. Tethys is a web-based application development framework for rapid deployment of end-user-focused tools that follow modern, consistent, scalable, cross-platform, reusable, web programming paradigms. Tethys is built on commonly used web programming frameworks (e.g., Django, GeoServer, PostGIS, OpenLayers). It is an open-source platform which allows anyone to observe and use the GGST as a decision support system to ensure sustainable usage of groundwater. It was developed in the BYU Hydroinformatics Laboratory and is now supported by a growing user and developer community. To access the GGST web application, visit https://tethys.byu.edu/apps/ggst/.

Anyone can open the app to view the currently uploaded regions and download the timeseries plots. View the screenshot below to see how to manipulate the map and download the data. Users can change the storage component displayed and the color bar style. Use the animation bar to view the storage change over time. Users can also download the time series plots as an image or as a table. The web app does not yet support downloading the NETCDF file raster that is displayed but this can be downloaded using the API.

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To upload and delete regions from the Tethys web application you must login with an admin account. If you have administrator (admin) access, follow the instructions on the Adding and Delete Regions page. If not, consider using our API method or feel free to reach out to our team if you would like a region uploaded.

The GGST app can be accessed in the following locations:

API and Google Colaboratory Notebook

In addition to using the GGST web application through one of the portals noted previously, it is also possible to access the core functionality of the GGST tool through a Python programming language-based application programmer interface (API). The advantages of the API are that you can retrieve data about a new region of interest without having admin access to the Tethys web application. You can also download a complete zip file of the regions netCDF raster files. You may implement the API on your own, but we recommend using the Google Colaboratory Notebook hosted on GitHub which is designed to run each of the API functions and help you download and visualize the data. For more detailed documentation please visit our API page. Below is a gif produced of the Niger Chad Basin using our Google Colab Notebook. Google Colaboratory is a web based Python programming environment hosted in the Google Cloud that is a component of the Google Drive environment.

_images/Chad_animation.gif