References

USACE Guidance

EM 1110-2-1415 (USACE, 1993)
USACE. 1993. Hydrologic Frequency Analysis. EM 1110-2-1415, 5 March 1993. General hydrologic frequency guidance; use Bulletin 17C for the annual peak-flow procedures identified in this chapter. Available from USACE Engineer Manuals.

EM 1110-2-1417 (USACE, 1994)
USACE. 1994. Flood-Runoff Analysis. EM 1110-2-1417, 31 August 1994. Chapter 10 addresses calibration; paragraph 17-3 discusses rainfall and runoff frequency. Available from USACE Engineer Manuals.

EM 1110-2-1619 (USACE, 2025)
USACE. 2025. Risk Assessment for Flood Risk Management and Coastal Storm Risk Management Studies. EM 1110-2-1619, 29 September 2025. Supersedes the 1 August 1996 edition and EP 1110-2-9 (31 July 1994), among other publications. Appendix C consolidates the hydrologic engineering studies design material and gives current planning policy precedence over conflicts. Available from USACE Engineer Manuals.

ER 1105-2-103 (USACE, 2023)
USACE. 2023. Policy for Conducting Civil Works Planning Studies. ER 1105-2-103, 7 November 2023, effective 7 December 2023. Supersedes Chapters 1, 2, and 3 of ER 1105-2-100 (22 April 2000). Paragraph 1-17b and Chapter 2 support the planning-process overview. Available from USACE Engineer Regulations.

ER 1110-2-1150 (USACE, 1999)
USACE. 1999. Engineering and Design for Civil Works Projects. ER 1110-2-1150, 31 August 1999. Paragraphs 13 through 16 describe engineering contributions during feasibility, design, construction, and operations; read with current planning policy. Available from USACE Engineer Regulations.

ER 1110-2-1464 (USACE, 1994)
USACE. 1994. Hydrologic Analysis of Watershed Runoff. ER 1110-2-1464, 30 June 1994. Paragraph 5 addresses study design. Available from USACE Engineer Regulations.

ECB 2026-1 (USACE, 2026)
USACE. 2026. Incorporating Resilience to Nonstationary Hydrometeorological Conditions in USACE Civil Works Studies, Designs, and Projects. ECB 2026-1, 9 January 2026; expires 9 January 2028. Paragraphs 4c through 4f and section 8 address applicability, exceptions, and frequency/duration analyses. WBDG copy.

Flood-Frequency Reference

Bulletin 17C (England et al., 2018; version 1.1, 2019)
England, J. F., Jr., and others. 2018. Guidelines for Determining Flood Flow Frequency: Bulletin 17C. U.S. Geological Survey Techniques and Methods, book 4, chapter B5, 148 p., version 1.1, May 2019. Replaces Bulletin 17B. Official USGS publication and revision record.

HEC Software Documentation

📖 HEC-HMS User's Manual

Current model setup, method selection, computation, and interpretation.

• Selecting a Loss Method — event and continuous applicability
• Selecting a Transform Method — lumped, distributed, and 2D runoff methods
• Selecting a Reach Routing Method — hydrologic routing assumptions
• Adjusting Parameters for the Forecast — forecast adjustments and the Combined Parameter Editor
• Ensemble Simulations — combining base simulations
• Erosion and Sediment Transport — sediment workflow and outputs

📐 HEC-HMS Technical Reference Manual

Method theory, equations, assumptions, and parameter estimation.

🛠️ HEC-HMS Tutorials and Guides

Worked exercises for configuring and evaluating models.

• Model Calibration and Validation — calibration and independent evaluation exercises
• Optimization Trial Enhancements — multiple targets, zonal parameters, and forecast optimization

📊 HEC-RAS Documentation

Hydraulic and sediment-model documentation.

📊 HEC-FDA Documentation

Flood risk management analysis, including expected annual damage and uncertainty.

📊 HEC-FIA Documentation

Event consequence analysis.

📊 HEC-SSP User's Manual

Hydrologic statistical analyses, including Bulletin 17 Analysis.

📊 HEC-ResSim Documentation

Reservoir-system operations modeling.

📊 HEC-EFM Documentation

Hydrologic and hydraulic relationships supporting ecosystem evaluation.