IDC: Integrated Water Flow Model Demand Calculator

Our Integrated Water Flow Model Demand Calculator (IDC) is a computer program used for calculating agricultural and urban water demands at a river basin. Agricultural water demand is calculated based on climate data, crop types, crop acreages, soil properties and irrigation methods. Urban demand is calculated based on population and per-capita water usage. IDC is the stand-alone root zone component of the Integrated Water Flow Model (IWFM).

License information: IDC is copyrighted by the State of California Department of Water Resources. It is licensed under the GNU General Public License. This means it can be copied, distributed, and modified freely, but you may not restrict others in their ability to copy, distribute, and modify it. See GNU General Public License for more details. 


We have several tools that are designed to help IWFM and IDC users to develop model input data, and to import and analyze model results in Excel.


  • IWFM Mesh Generator (Last updated: November 8, 2021)  This is a mesh generator that is integrated into ESRI's ArcMap software, version 10.8.x. It utilizes shapefiles to define model boundary, streams, enforcement lines, holes and wells to generate a triangular, quarilateral or mixed triangular-quadrilateral finite element mesh. It uses Triangle, developed by Dr. Jonathan Richard Shewchuk, and Gmsh, developed by Christophe Geuzaine and Jean-François Remacle, as the mesh generator engines. The mesh can be converted to a shapefile to perform various data analysis to develop input data (e.g. soil properties, land use distribution, development of stratigraphic layers) for IWFM applications. Groundwater and stream nodes as well as finite elements can be numbered automatically and the IWFM mesh files can be exported to text files. After downloading the ESRI add-in installation file, double-click on it and follow the instructions. After installation, start ArcMap and click the "IWFM Mesh Generator" button.
  • IWFM Tools Add-in for Excel 2016: (Last updated: July 24, 2018)  (Download either for 32-bit MS Office or 64-bit MS Office) This tool is tested under Windows 10 and installs as a new tab named "IWFM Tools" into Excel 2016, and currently includes four utilities (Note: The Budget-To-Excel utility will no longer work for Budget binary files generated by IWFM v3.02 or v4.0):
                i. data column export to a text file
                ii. Water Year-Month table generator
                iii. Budget-To-Excel data import utility
                iv. Z-Budget-To-Excel data import utility
    The first utility is useful when IWFM input data is prepared in Excel and when this data needs to be exported into a text file with right-aligned data columns. The second utility is used to convert time series data into a Water Year-Month table and optinally generate charts. The third and fourth utilities are used to quickly import data from IWFM Budget and Z-Budget HDF5 files into Excel. After downloading the setup file, double-click it and follow the instructions for installation.
  • Soil Data Builder(Last updated: June 1, 2016) This tool processes the SSURGO soil database from NRCS and creates text files that store root zone data required by IWFM and IDC. These text files can then be opened in ESRI's ArcGIS along with the SSURGO shapefiles, and processed to generate soil parameters to be input to IWFM or IDC models. This tool requires MS Access 2007 or higher to be installed on the user's computer. Once installed, you can find the tool under Start -> All Programs -> IWFM.  
  • Soil Data Builder with GIS (Last updated: February 17, 2017) This utility is the Soil Data Builder tool (above) that is integrated within ESRI's ArcMap. It processes multiple SSURGO soil database from NRCS for an IWFM or IDC application and generates the soil parameter values for model cells. This utility can also be used to generate soil parameters for any polygon layer, not just for IWFM or IDC model grids. The utility has been tested with ArcMap v10.3 under Windows 10 OS. After downloading the setup executable file, double-click on it and follow the instructions. After installation, start ArcMap and click the "IWFM SDB-GIS" command button. 
  • IWFM PEST Utilities (Last updated: October 28, 2013) These utilities are developed to aid the user in automatic calibration of an IWFM application by linking it to the Parameter ESTimation tool (PEST). The download includes the documentation, an example, executables for both Windows and Linux Ubuntu OS, and the source code for the utility programs.
  • Land Use Adjustment Preprocessor (Last updated: September 18, 2017)  (Download either for IWFM v3.xIWFM v4.0 or IWFM-2015) The land use adjustment preprocessor allows the user to generate a time series data set of elemental land use areas based on subregional or model-wide time series data and elemental survey data. The download includes the source code, executable program, example input and output files, and program description.

The IWFM User’s Group is part of CWEMF, hosted by both DWR and U.S. Bureau of Reclamation in an effort to encourage development and understanding of the model. If you're new to the users group and would like to receive information about the upcoming meetings, or to request a copy of the presentations from the previous meetings, please send an e-mail to

  • Meeting materials – December 18, 2019
  • Meeting materials – December 13, 2018