Hydrologic Engineering Center - Statistical Software Program (HEC-SSP)

Purpose: Statistical analyses of hydrologic data
Developer: U.S. Army Corps of Engineers Hydrologic Engineering Center (USACE HEC)
Key Features: Performs different types of statistical analysis; Calculates confidence limits
Latest Release: Version 2.0, October 2010
OS Platform: Windows
Cost: Free
Related Software: IH-Floods, Peak-FQ
Website: HEC-SSP (summary, features, users manual, downloads, etc)

Introduction

The HEC-SSP performs statistical analyses of hydrologic data. The program has separate components to perform the following analyses:

Flow Frequency Analysis (FFA); The FFA component assists in annual peak flow frequency analyses

General Frequency Analysis (GFA): . The GFA component has multiple methods, and assists in frequency analysis of annual peak flows as well as stage and precipitation data.

Volume Frequency Analysis (VFA): The VFA component assists in volume frequency analysis of daily flow or stage data.

Duration Analysis (DA): The DA component can be applied on any variable that has data at regular intervals, and used to estimate percent of time that a variable equals or exceeds a specific value.

Coincident Frequency Analysis (CFA): The CFA component is used to compute exceedance frequency relationship of a variable that is a function of two other variables.

Curve Combination Analysis (CCA): The CCA combines multiple frequency curves into a single frequency curve.

Performing a statistical analysis on any of the components assumes that the samples (discharge data) obtained are representative of the parent distribution. The program uses the following five types of statistical distributions to model the parent distribution: none, normal, log normal, Pearson III, and log Pearson III. HEC-SSP can be employed in a wide variety of applications, from the design of hydraulic structures to basin planning.

The HEC-SSP software has several key software features, including a Graphical User Interface (GUI), confidence intervals, and reporting tools. The HEC-FDA was developed by the Hydrologic Engineering Center of the United States Army Corps of Engineers, and is only supported on the Windows operating system.

Advantages and Limitations

Advantages Limitations
  • Data can be entered or imported manually from multiple sources, such as Excel sheets and text files
  • Allows users to choose a method as well as options for statistical analysis
  • Detailed technical report and users' manual
  • Accounts for uncertainty by providing confidence intervals
  • No support provided for users other than U.S. Army Corps of Engineers
  • Model code is not publicly available
  • Statistical analysis does not include extreme value theory or regional frequency analysis
  • Assumes stationarity (no major changes in the watershed and no impact from climate change)

Illustrative Screens

Sample Applications

Africa East Asia and the Pacific Europe & Central Asia Latin America & the Caribbean Middle East and North Africa South Asia
Argentina (Rainfall prediction)
Venezuela (Rainfall Analysis)

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