HSPEXP+ is RESPEC’s latest version of an open-source water resources applications software, now available free of charge on GitHub.com. HSPEXP+ stands for “an Enhanced Expert System for Calibration of HSPF.”  The comprehensive analytical tool is used worldwide by the online community of hydrology professionals in watershed modeling, hydrologic and water quality calibration, quality assurance/quality control (QA/QC), sensitivity analysis, uncertainty analysis, and scenario comparisons for HSPF models.

Supporting watershed modeling and water quality projects, RESPEC’s HSPEXP+ includes features like constituent reports for organic material simulated as biochemical oxygen demand (BOD), heat, dissolved oxygen, and general quality (GQUAL) constituents like metals and indicator bacteria, in addition to the water sediment, total nitrogen, and total phosphorus reports. Reports and graphs for additional constituents will assist modelers in obtaining better insights for their models. These additional reports can be used to conduct efficient QA/QC of a Hydrologic Simulation Program‑FORTRAN (HSPF) model.

HSPEXP+ also includes the Multi Simulation Manager. Using the Multi Simulation Manager, a modeler can provide multiple parameter values ahead of time and conduct thousands of model simulations without constant user intervention. Multi Simulation Manager can be used to conduct sensitivity analysis, uncertainty analysis, scenario selection, and model calibration.

HSPEXP+ provides several additional reports and an advanced graphing functionality to assist a modeler in obtaining meaningful insights about the model on an overall basis, as well as on an operation-by-operation basis.

HSPEXP+ generates time series plots comparing observed and simulated data, hydrology calibration statistics, hydrology calibration advice, constituent balance reports, reach budget reports, box-whisker plots of constituent loading by land use, monthly constituent loadings by land use, and Regan plots to evaluate model stability. HSPEXP+ is an open-source project and is available for no cost at RESPEC’s
GitHub site. A detailed description of the individual capabilities of HSPEXP+ is provided at https://www.chijournal.org/C422.


Clients use HSPEXP+ to:

  • Generate graphs, error statistics, and reports to assist in HSPF hydrology and water quality calibration and validation.
  • Conduct QA/QC of existing HSPF models.
  • Conduct HSPF model scenario analysis.
  • Conduct sensitivity and uncertainty analyses of an HSPF model.
  • Create additional reports to gain better insight into models.
  • Conduct thousands of model simulations.
  • Utilize enhanced Scenario selection
  • Perform more accurate model calibration


HSPEXP+ Tutorial Videos: