Friday, January 18, 2019

Exploring the power of AnAqSim using QGIS

FlexAEM recently announced the addition of a new set of exercises to the AnAqSim Instructional Series! The new set of exercises demonstrates how groundwater professionals can use the spatial data management and analysis features of QGIS, a free and powerful open-source geospatial information system (GIS) software package to enhance the groundwater modeling capabilities of AnAqSim. 

The series illustrates how QGIS can generate spatial data describing hydrologic and hydrogeologic features to facilitate groundwater model construction, and then import and process AnAqSim model output data to display model results such as water level contours and flow pathlines in both 2D and 3D. For AnAqSim users who may be less familiar with QGIS, the series includes an overview of QGIS and its capabilities, including compatible file formats, vector and raster analysis tools, editing and management tools, and much more.

The new series includes exercises that demonstrate how to perform a number of useful functions with QGIS, including the digitization of site features to create model elements. For example, river or ocean boundaries, or groundwater divides, can be digitized and transferred to AnAqSim to represent model boundary conditions (Figure 1). The boundaries of other features, such as lakes and ponds, can also be digitized in QGIS and placed in the AnAqSim model using appropriate element properties (Figure 2).

Figure 1
Figure 2

The exercises also demonstrate how QGIS can be used to create rivers and assign elevation data to points along a river system. Users will learn how to digitize a river system using a basemap, and then use a raster file to obtain elevation values for the selected points along the river. Users also learn how to easily format the river data and import it into AnAqSim.

Basemaps for digitizing model elements or preparing river data can also be created in QGIS for use in AnAqSim, or basemap images from other sources can be imported into QGIS to facilitate basemap creation. There is a multitude of freely available GIS data available online, which can be downloaded, viewed, and analyzed in QGIS. The exercises included in the set demonstrate how to use these data to create custom basemaps, and then export those basemaps as a DXF file for use in AnAqSim. For example, the set include an exercise that provides a step-by-step tutorial on how to obtain a web map hosted by the USGS, digitize the boundary of a feature using the web map, and then export the digitized boundary to AnAqSim to help establish model boundary conditions.

Figure 3
Figure 4
Finally, the exercise set demonstrates how to export water level contours (Figure 3) or groundwater flow pathlines (Figure 4) generated from an AnAqSim model run, import the results into QGIS, and view them in 3D. Any model result from AnAqSim that contains elevation values can be viewed in 3D in QGIS, which allows users to easily visualize model scenarios.

To learn more about QGIS and how it can be used with AnAqSim, check out the new addition to the AnAqSim Instructional Series at  

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