Also known as
Model type Modular
Model part of larger framework
Incorporated models or components:
Spatial dimensions
Spatial extent
Model domain Hydrology
One-line model description PIHM is a multiprocess, multi-scale hydrologic model.
Extended model description PIHM is a multiprocess, multi-scale hydrologic model where the major hydrological processes are fully coupled using the semi-discrete finite volume method. PIHM is a physical model for surface and groundwater, “tightly-coupled” to a GIS interface. PIHMgis which is open source, platform independent and extensible. The tight coupling between GIS and the model is achieved by developing a shared data-model and hydrologic-model data structure.

basins, continental,

First name Christopher
Last name Duffy
Type of contact Project manager
Institute / Organization Penn State University
Postal address 1 212 Sackett Bldg
Postal address 2 Civil & Environmental Engineering
Town / City University Park
Postal code 16802
State Pennsylvania
Country United States
Email address
Phone +1 814 863-4384
Fax +1 814-863-7304

First name Mukesh
Last name Kumar
Type of contact Technical contact
Institute / Organization
Postal address 1
Postal address 2
Town / City
Postal code
Email address

First name Gopal
Last name Bhatt
Type of contact Technical contact
Institute / Organization
Postal address 1
Postal address 2
Town / City
Postal code
Email address

Supported platforms Unix, Linux, Mac OS, Windows
Other platform Platform independent
Programming language C, C++
Other program language
Code optimized
Multiple processors implemented
Nr of distributed processors
Nr of shared processors
Start year development 2002
Does model development still take place? Yes
If above answer is no, provide end year model development
Code development status
When did you indicate the 'code development status'?
Model availability As code
Source code availability
(Or provide future intension)
Through web repository
Source web address
Source csdms web address
Program license type GPL v2
Program license type other
Memory requirements --
Typical run time --

Describe input parameters PIHM is an integrated finite volume hydrologic model. It simulates channel routing, overland flow and groundwater flow in fully coupled scheme. It uses semi-discrete Finite Volume approach to discretize PDE (equations governing physical processes) into ODE to form a system of ODEs and solved with SUNDIALS solver (LBL).
PIHM incorporates an object-oriented model data structure which provides extensibility and efficient storage of data at the same time. PIHM v2.0 requires the following input files:
  • projectName.txt : This file will have the project name as its content.
  • .mesh File : Spatial information of Nodes and Irregular Meshes (TINs)
  • .att File : Attribute defining different classes an element belongs to
  • .soil File : Soil properties
  • .geol : Geologic properties
  • .lc file : Vegetation parameters of different land cover types
  • .riv file : Spatial, geometry and material information of river segments
  • .forc file : All the forcing variables (forcing time-series)
  • .ibc file : Boundary condition information for elements
  • .para file : Control parameters (solver options; model modes; error control)
  • .init : If initial condition input is through a file
  • .calib : Calibration parameters and process controls
Input format ASCII
Other input format Shape file
Describe output parameters PIHM v2.0 uses Net_CDF for state and flux output. Details are under development (April 2009) and will be complete July 2009
Output format ASCII
Other output format NetCDF
Pre-processing software needed? No
Describe pre-processing software
Post-processing software needed? No
Describe post-processing software
Visualization software needed? Yes
If above answer is yes
Other visualization software any software able to visualize gridded data (RiverTools / 3DEM)

Describe processes represented by the model The Penn State Integrated Hydrologic Model (PIHM) is a fully coupled multiprocess hydrologic model. Instead of coupling through artificial boundary conditions, major hydrological processes are fully coupled by the semi-discrete finite volume approach. For those processes whose governing equations are partial differential equations (PDE), we first discretize in space via the finite volume method. This results in a system of ordinary differential equations (ODE) representing those procesess within the control volume. Within the same control volume, combining other processes whose governing equations are ODE’s, (e.g. the snow accumulation and melt process), a local ODE system is formed for the complete dynamics of the finite volume.
Describe key physical parameters and equations Processes include: 2-D overland flow, 2-D groundwater flow, 1-D soil moisture, 1-D channel flow, snow/melt, et, vegetation water use by NLCD,
Describe length scale and resolution constraints typically based on original DEM used to develop the watershed model
Describe time scale and resolution constraints fully implicit, time adaptive, based on the CVODE ODE solver from LBL
Describe any numerical limitations and issues Solver is efficient and accurate for very stiff systems of equations

Describe available calibration data sets Upper Juniata River 875 km^2: see:
Upload calibration data sets if available:
Describe available test data sets Upper Juniata River 875 km^2: see:
Upload test data sets if available:
Describe ideal data for testing PIHM is a distributed watershed model that can represent surface/subsurface processes at scales ranging from a few hundred m^2 to 10,000 km^2. However, large systems will require the parallel version currently under development

Do you have current or future plans for collaborating with other researchers? We have several other extensions to PIHM under development: solute transport, sediment transport, 3-D Richard's Equation. Full information can be found at:
Is there a manual available? Yes
Upload manual if available:
Model website if any
Model forum / discussion board
Comments --

This part will be filled out by CSDMS staff

OpenMI compliant No but possible
BMI compliant No but possible
WMT component No but possible
PyMT component
Is this a data component
Can be coupled with:
Model info
Christopher Duffy
Kumar, Bhatt
Nr. of publications: 43
Total citations: 1083
h-index: 20
Qrcode PIHM.png
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Nr. of publications: 43
Total citations: 1083
h-index: 20

Featured publication(s)YearModel describedType of ReferenceCitations
Qu, Yizhong; Duffy, Christopher J.; 2007-08-01. A semidiscrete finite volume formulation for multiprocess watershed simulation: MULTIPROCESS WATERSHED SIMULATION. Water Resources Research, 43, . 10.1029/2006WR005752
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Model overview 227
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Input Files

Output Files