Welcome to the U.S. Army Corps of Engineers, Hydrologic Engineering Center's (HEC) Statistical Software Package (HEC-SSP). HEC-SSP software allows users to perform statistical analyses of hydrologic data. The purpose of this guide is to illustrate the input and output results for 35 example problems. The example problems are provided to illustrate the use of specific options in HEC-SSP and to assist in verifying the correct execution of the HEC-SSP software. The HEC-SSP Examples guide provides a brief description of each example. 

Out of the 35 example problems, the first six examples are the same examples described in the HEC-FFA (Hydrologic Engineering Center's Flood Frequency Analysis) software user's manual. Furthermore, a comparison between the HEC-FFA and HEC-SSP results verifies that the HEC-SSP software produces the same results as HEC-FFA for these six data sets. The first six examples were analyzed in HEC-SSP with both Bulletin 17 and General Frequency Analysis; however, this guide displays only the results obtained using a Bulletin 17 Analysis. Full results for both analyses are included in the SSP_Examples.ssp study and show that the results are the same whether a Bulletin 17 or General Frequency Analysis was performed.

Within the first six examples, the weighted skew option was selected and a regional skew value was entered from the generalized skew map of the United States provided within Bulletin 17B (Plate 1).

Overview of Example Problems

Example NumberExample Problem TitleSSP_Examples.ssp
Analysis NameData Record Name
1

Fitting the Log-Pearson Type III Distribution

FFA Test 1Fishkill Creek-Beacon, NY
2Analysis with High OutliersFFA Test 2Floyd River-James IA
3Testing and Adjusting for a Low OutlierFFA Test 3Back Creek-Jones Springs
4Zero Flood YearsFFA Test 4Orestimba Creek-Newman, CA
5Confidence Limits and Low Threshold DischargeFFA Test 5Kaskaskia River-Vandalia, IL
6Use of Historic DataFFA Test 6Ridley Creek-Moylan, PA
7Analyzing Stage DataStage Analysis Test 7Reservoir Stage
8Using User-Adjusted StatisticsLocal Runoff at Alb Test 8Rio Grande at Alb Local Runoff
9General Frequency - Graphical AnalysisReg Flow Rio Grande Test 9Rio Grande at Alb Reg Flow
10Volume Frequency Analysis, Maximum FlowsUnreg Flow Rio Grande Test 10Rio Grande at Alb Unreg Daily
11Volume Frequency Analysis, Minimum FlowsLow Flow Analysis Test 11Chattahoochee River
12Duration Analysis, Bin (STATS) MethodFishkill Creek Test 12Fishkill Creek-Daily Flow
13Duration Analysis, Rank All Data MethodDuration Curve Test 13Wondering River-Franklin
14Duration Analysis, Manual EntryManual Duration Curve Test 14Not Applicable
15Coincident Frequency Analysis, A and B can be Assumed IndependentCoincident Freq Test 15Not Applicable
16Coincident Frequency Analysis, A and B cannot be Assumed IndependentCoincident Freq Test 16Not Applicable
17Balanced Hydrograph Analysis, Using an Historical Event HydrographBalanced Hydrograph Test 17Sinnemahoning Creek-Hourly
18Balanced Hydrograph Analysis, Using a Triangular-shaped HydrographBalanced Hydrograph Test 178Sinnemahoning Creek-Triangular
19Curve Combination Analysis, Combining Multiple Frequency Curves using Graphical TechniquesCurve Combination Test 19Not Applicable
20Distribution Fitting, Analyzing Model Uncertainty Using a Time Series of Annual Maximum StreamflowDistribution Fitting Test 20Potomac River-Flow-Annual Peak
21Distribution Fitting, Analyzing a Time Series of Daily Average Flow Using Time Window, Seasonal, and Annual Maxima FilteringDistribution Fitting Test 21Sinnemahoning Creek-Daily
22Distribution Fitting, Analyzing a Time Series of Daily Average Flow Using Time Window, Seasonal, and Peaks Over Threshold FilteringDistribution Fitting Test 22Sinnemahoning Creek-Daily
23Distribution Fitting, Analyzing a Time Series of Daily Precipitation Accumulation Using Peaks Over Threshold FilteringDistribution Fitting Test 23Hawley 1 E PA-Daily-Precip-Inc
24Distribution Fitting, Analyzing a Time Series of Daily Average Snow Water Equivalent Using Annual Maxima FilteringDistribution Fitting Test 24Little Meadows-SWE
25Distribution Fitting, Analyzing a Time Series of Daily Average Flow to Estimate Flood SeasonalityDistribution Fitting Test 25South Fork Shoshone River-Daily
26Distribution Fitting, Analyzing a Paired Data Record of Hydrologic Model OutputDistribution Fitting Test 26MCMC OUTPUT-TC
27Mixed Population, Combining Two Frequency Curves using the Probability of Union ConceptMixed Population Test 27

Kettle Creek-Summer-Flow-Annual Peak

Kettle Creek-Winter-Flow-Annual Peak

28Mixed Population, Combining Three Frequency Curves using the Probability of Union ConceptMixed Population Test 28Not Applicable
29General Frequency, Fitting a Log Pearson Type III Distribution using the Expected Moments AlgorithmGeneral Frequency EMA TestSouth Fork Shoshone River-Flow-Annual Peak
30General Frequency, Fitting an Analytical Distribution to a Precipitation Time SeriesGeneral Frequency Precip TestHawley 1E PA-3DAY-Precip-AMS
31

Volume Frequency, Fitting a Family of Log Pearson Type III Distributions to Volume-Duration Data using the Expected Moments Algorithm

Sinnemahoning_VolumeFrequencySinnemahoning Creek-Daily
32Data Filtering, Extracting an Annual Maximum Series
Jamestown-Daily Max Temp
33Data Filtering, Extracting a Partial Duration Series
Miami Beach-Daily Precip
34Data Filtering, Using Multiple Filters
Palisades Dam-Daily Inflow
35Data Filtering, Starting Pool/Elevation Filtering
Sayers Dam-Daily Elevation

Installing HEC-SSP Example Data

To install this study on your computer open the HEC-SSP software and select the Help | Install Example Data menu command. After the install is complete, open the SSP_Examples.ssp study and the HEC-SSP main window will appear as shown in Figure 1. 

Figure 1. SSP Examples Study

After opening the SSP_Examples.ssp study for the first time on your computer, you must compute each example before viewing tabular and graphical results.

The SSP_Examples.ssp study includes, nine Bulletin 17B analyses, eleven General Frequency analyses, three Volume Frequency analyses, three Duration analyses, two Coincidence Frequency analyses, one Curve Combination analysis, two Balanced Hydrograph analyses, seven Distribution Fitting analyses, and two Mixed Population analyses in this study. The following sections document each of the example data sets. HEC-SSP Bulletin 17C Examples details ten additional examples which make use of the Expected Moments Algorithm and Bulletin 17C procedures.