A model-independent open-source geospatial tool for managing point-based environmental model simulations at multiple spatial locations

• Geospatial Simulation is a Quantum GIS plug-in that facilitates spatial modeling.
• The software is open-source and freely available for download and use.
• The software can be implemented with any point-based environmental model.
• Tools facilitate geospatial data processing, model simulation and optimization.
• A case study demonstrates the main features and advantages of the software.

A novel geospatial tool box named Geospatial Simulation (GeoSim) has been developed, which can be used to manage point-based model simulations at multiple locations using geospatial data within a geographic information system (GIS). The objectives of this paper were to describe GeoSim and demonstrate its use. GeoSim has been developed as a plug-in for Quantum GIS, and both of these software programs are open-source and freely available. An important feature of GeoSim is its model-independent nature, meaning any point-based simulation model that uses ASCII files for input and output can be managed spatially. GeoSim facilitates the transfer of geospatial data from the GIS database to the model input files and from the model output files back to the GIS database. GeoSim presently includes six software tools, each with a graphical user interface. A case study demonstrates the use of GeoSim for processing geospatial data layers at a field site, conducting spatial model simulations, and optimizing model parameters for site-specific conditions. Two cropping system models, AquaCrop and the DSSAT Cropping System Model, were implemented to simulate seed cotton yield in response to irrigation management, nitrogen management, and soil texture variability for a 14 ha study area near Lamesa, Texas. Geoprocessing tools within GeoSim were able to summarize 5592 data points within 405 polygon features in 3.8 s. Simulation tools were able to swap 33,316 and 44,550 parameters values to complete 405 spatial simulations with the AquaCrop and DSSAT models in 112 s and 398 s, respectively. These results demonstrate the utility of GeoSim for summarizing large geospatial data sets and transferring the data to the file formats of multiple models. Simulation duration was increased as compared to stand-alone model simulations without parameter swapping, which may be problematic for applications requiring large numbers of simulations. The flexible design of GeoSim is intended to support spatial modeling exercises for a variety of models and environmental applications.