IWFM: Integrated Water Flow Model
Our Integrated Water Flow Model (IWFM) is a computer program used for water resources management and planning within a basin. It calculates groundwater flows, soil moisture movement in the topsoil, stream flows, land surface flows and flow exchange between the groundwater, streams and land surface as generated by rainfall, agricultural irrigation, and municipal and industrial water use. IWFM also calculates agricultural water demands based on crop types, crop acreages, soil types, irrigation methods and rainfall rates, as well as the municipal and industrial water demands based on population and per-capita water use rates. IWFM is a powerful tool that can help water managers understand the historical evolution of the surface and subsurface water flows within their basin, and to plan the use of groundwater and surface water to meet future agricultural, municipal and industrial water demands.
DWR is providing IWFM to Groundwater Sustainable Agencies (GSAs) to develop their Groundwater Sustainability Plans (GSPs) as a tool that can be used for sustainable groundwater management.
License information: IWFM 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.
A summary of IWFM features, example applications and selected publications can be found in the IWFM factsheet.
There are several versions of IWFM, the latest being IWFM version 2015. If you are new to IWFM, we recommend using this version as the older versions, 4.0 and 3.02, are archival and no longer updated.
- Huang, G., and T. Kadir. 2016. Estimates of natural and unimpaired flows for the Central Valley of California: WY 1922-2014
- Harter, T., and H. Morel-Seytoux. 2013. Peer review of the IWFM, MODFLOW and HGS model codes: Potential for water management applications in California's Central Valley and other irrigated groundwater basins.
- Brush, C.F., and E.C. Dogrul. 2013. DWR Technical Memorandum: Programs to support calibration of Integrated Water Flow Model (IWFM) using PEST: Documentation of PEST-IWFM utilities.
- Dogrul, E.C., W. Schmid, R.T. Hanson, T. Kadir, and F. Chung. 2011. Integrated Water Flow Model and Modflow-Farm Process: A comparison of theory, approaches, and features of two integrated hydrologic models.
- Schmid, W., E.C. Dogrul, R.T. Hanson, T. Kadir, and F. Chung. 2011. Comparison of simulations of land-use specific water demand and irrigation water supply by MF-FMP and IWFM.
- Dixon, M.F., Z. Bai, C.F. Brush, F.I. Chung, E.C. Dogrul, and T.N. Kadir. 2010. Accuracy control and performance enhancement of linear solvers for the Intgerated Water Flow Model.
- Ercan, A. 2006. Verification problems for IWFM.
NOTE: Published articles are available upon request.
- Dogrul, E. C., C.F. Brush, T.N. Kadir. 2016. Groundwater modeling in support of water resources management and planning under complex climate, regulatory, and economic stresses. Water 8, (12): 592.
- Ercan, A., E.C. Dogrul, T.N. Kadir. 2016. Investigation of the groundwater modelling component of the Integrated Water Flow Model (IWFM). Hydrological Sciences Journal 61, (16): 2834-2848.
- Dogrul, E. C., T. N. Kadir, C. F. Brush, F. I. Chung. 2016. Linking groundwater simulation and reservoir system analysis models: The case for California's Central Valley. Environmental Modelling & Software 77, (Mar): 168-182.
- Medellin-Azuara, J., D. MacEwan, R. E. Howitt, G. Koruakos, E. C. Dogrul, C. F. Brush, T. N. Kadir, T. Harter, F. Melton, J. R. Lund. 2015. Hydro-economic analysis of groundwater pumping for irrigated agriculture in California's Central Valley, USA. Hydrogeology Journal 23, (6) (Sep): 1205-1216.
- Scherberg, J., T. Baker, J. S. Selker, and R. Henry. 2014. Design of managed aquifer recharge for agricultural and ecological water supply assessed through numerical modeling. Water Resources Management 28, (14) (Nov): 4971-4984.
- Dale, L. L., E. C. Dogrul, C. F. Brush, T. N. Kadir, F. I. Chung, N. L. Miller, and S. D. Vicuna. 2013. Simulating the impact of drought on California's Central Valley hydrology, groundwater and cropping. British Journal of Environment and Climate Change 3, (Jul-Sep): 271-291.
- Heinzer, T. J., M. D. Williams, E. C. Dogrul, T. N. Kadir, C. F. Brush, and F. I. Chung. 2012. Implementation of a feature-constraint mesh generation algorithm within a GIS. Computers & Geosciences 49, (Dec): 46-52.
- Dixon, M. F., Z. Bai, C. F. Brush, F. I. Chung, E. C. Dogrul, and T. N. Kadir. 2011. Error control of iterative linear solvers for integrated groundwater models. Ground Water 49, (6) (Nov-Dec): 859-865.
- Miller, N. L., L. L. Dale, C. F. Brush, S. D. Vicuna, T. N. Kadir, E. C. Dogrul, and F. I. Chung. 2009. Drought resilience of the California Central Valley surface-ground-water-conveyance system. Journal of the American Water Resources Association 45, (4) (Aug): 857-866.
- Dogrul, E. C., and T. N. Kadir. 2006. Flow computation and mass balance in Galerkin finite-element groundwater models. Journal of Hydraulic Engineering 132, (11) (Nov): 1206-1214.
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: March 9, 2017) This is a mesh generator that is integrated into ESRI's ArcMap software. 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 setup executable 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.x, IWFM 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.
Newsletters & Subscriptions
User’s Group: 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. Information pertaining to the upcoming quarterly meetings, as well as information regarding the previous meetings will be accessible through the CWEMF website. If you're new to the users group please send IWFMtechsupport@water.ca.gov your contact information so we can update you on the next meeting.
Email Us: IWFMtechsupport@water.ca.gov