SMPP: The Spreadsheet-Based MODFLOW Pre-Processor.

Several packages in MODFLOW 2000 (or a later version), such as the Farm Process package (FMP), were developed to better simulate the groundwater flow system and its related water and nonwater components. These newly developed packages are more data demanding because they use more sophisticated algorithms to closely represent real hydrological processes. Substantial analysis of the spatial and temporal data sets is required to generate the correct model files. The Spreadsheet-Based MODFLOW Pre-Processor (SMPP) was developed to support efficient handling of data in the FMP and other MODFLOW packages. The final results from SMPP are input files for the MODFLOW packages. SMPP was developed in Microsoft Excel using Visual Basic Application (VBA) scripts and is therefore intended to be used in Microsoft Excel 2010 or later with other GIS tools. It gathers all the needed data for model establishment in the embedded spreadsheets. The spreadsheet format was chosen because (1) this data processing tool is familiar to groundwater modelers; (2) the formulas are flexible and the results are calculated instantly; and (3) it provides prompt graphical or visual representations. Therefore, modelers can readily perform complicated analyses of large amounts of groundwater data with spreadsheets (Hunt 2005). The need for spatial information is increasing in MODFLOW models because the new packages involve more sophisticated algorithms and higher precision in representing hydrologic elements in spatial scales. However, carrying out complicated spatial analysis tasks using the groundwater modeling GUI software could be more challenging than using GIS tools. SMPP is designed to adopt