HEC-SSP Examples Introduction

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 Number	Example Problem Title	SSP_Examples.ssp
Example Number	Example Problem Title	Analysis Name	Data Record Name
1	Fitting the Log-Pearson Type III Distribution	FFA Test 1	Fishkill Creek-Beacon, NY
2	Analysis with High Outliers	FFA Test 2	Floyd River-James IA
3	Testing and Adjusting for a Low Outlier	FFA Test 3	Back Creek-Jones Springs
4	Zero Flood Years	FFA Test 4	Orestimba Creek-Newman, CA
5	Confidence Limits and Low Threshold Discharge	FFA Test 5	Kaskaskia River-Vandalia, IL
6	Use of Historic Data	FFA Test 6	Ridley Creek-Moylan, PA
7	Analyzing Stage Data	Stage Analysis Test 7	Reservoir Stage
8	Using User-Adjusted Statistics	Local Runoff at Alb Test 8	Rio Grande at Alb Local Runoff
9	General Frequency - Graphical Analysis	Reg Flow Rio Grande Test 9	Rio Grande at Alb Reg Flow
10	Volume Frequency Analysis, Maximum Flows	Unreg Flow Rio Grande Test 10	Rio Grande at Alb Unreg Daily
11	Volume Frequency Analysis, Minimum Flows	Low Flow Analysis Test 11	Chattahoochee River
12	Duration Analysis, Bin (STATS) Method	Fishkill Creek Test 12	Fishkill Creek-Daily Flow
13	Duration Analysis, Rank All Data Method	Duration Curve Test 13	Wondering River-Franklin
14	Duration Analysis, Manual Entry	Manual Duration Curve Test 14	Not Applicable
15	Coincident Frequency Analysis, A and B can be Assumed Independent	Coincident Freq Test 15	Not Applicable
16	Coincident Frequency Analysis, A and B cannot be Assumed Independent	Coincident Freq Test 16	Not Applicable
17	Balanced Hydrograph Analysis, Using an Historical Event Hydrograph	Balanced Hydrograph Test 17	Sinnemahoning Creek-Hourly
18	Balanced Hydrograph Analysis, Using a Triangular-shaped Hydrograph	Balanced Hydrograph Test 178	Sinnemahoning Creek-Triangular
19	Curve Combination Analysis, Combining Multiple Frequency Curves using Graphical Techniques	Curve Combination Test 19	Not Applicable
20	Distribution Fitting, Analyzing Model Uncertainty Using a Time Series of Annual Maximum Streamflow	Distribution Fitting Test 20	Potomac River-Flow-Annual Peak
21	Distribution Fitting, Analyzing a Time Series of Daily Average Flow Using Time Window, Seasonal, and Annual Maxima Filtering	Distribution Fitting Test 21	Sinnemahoning Creek-Daily
22	Distribution Fitting, Analyzing a Time Series of Daily Average Flow Using Time Window, Seasonal, and Peaks Over Threshold Filtering	Distribution Fitting Test 22	Sinnemahoning Creek-Daily
23	Distribution Fitting, Analyzing a Time Series of Daily Precipitation Accumulation Using Peaks Over Threshold Filtering	Distribution Fitting Test 23	Hawley 1 E PA-Daily-Precip-Inc
24	Distribution Fitting, Analyzing a Time Series of Daily Average Snow Water Equivalent Using Annual Maxima Filtering	Distribution Fitting Test 24	Little Meadows-SWE
25	Distribution Fitting, Analyzing a Time Series of Daily Average Flow to Estimate Flood Seasonality	Distribution Fitting Test 25	South Fork Shoshone River-Daily
26	Distribution Fitting, Analyzing a Paired Data Record of Hydrologic Model Output	Distribution Fitting Test 26	MCMC OUTPUT-TC
27	Mixed Population, Combining Two Frequency Curves using the Probability of Union Concept	Mixed Population Test 27	Kettle Creek-Summer-Flow-Annual Peak Kettle Creek-Winter-Flow-Annual Peak
28	Mixed Population, Combining Three Frequency Curves using the Probability of Union Concept	Mixed Population Test 28	Not Applicable
29	General Frequency, Fitting a Log Pearson Type III Distribution using the Expected Moments Algorithm	General Frequency EMA Test	South Fork Shoshone River-Flow-Annual Peak
30	General Frequency, Fitting an Analytical Distribution to a Precipitation Time Series	General Frequency Precip Test	Hawley 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_VolumeFrequency	Sinnemahoning Creek-Daily
32	Data Filtering, Extracting an Annual Maximum Series		Jamestown-Daily Max Temp
33	Data Filtering, Extracting a Partial Duration Series		Miami Beach-Daily Precip
34	Data Filtering, Using Multiple Filters		Palisades Dam-Daily Inflow
35	Data 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. HEC-SSP Example Studies

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.