Hydrologic engineers in U.S. Army Corps of Engineers (USACE) offices support planning, designing, operating, permitting, and regulating activities by providing information about watershed runoff under existing and future conditions, with and without water-control features. The Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS) simulates watershed processes to estimate runoff volumes, peak flow rates, hydrograph timing, and, with the appropriate methods and inputs, sediment yields and transport. Hydraulic, consequence, or other analyses may be needed to turn these outputs into decision information.
The guide illustrates applications in eight study chapters:
Determine the information needed to make those decisions.
Select the spatial and temporal extent and resolution of the analysis.
Select methods whose assumptions and data requirements fit the study.
Estimate and calibrate parameters, and validate against independent observations where data permit.
Develop initial and boundary conditions appropriate to the application.
Apply the model and review computation messages and results.
Check physical plausibility, evaluate sensitivity, and characterize uncertainty relevant to the decision.
Process the results into the required decision information and document inputs, assumptions, model versions, and limitations.
The original Case Studies remain historical examples. Current-guidance notes and current-software tips explain developments that may affect a new application; they do not revise the original computed results. See the Preface for the callout convention and How Should HEC-HMS be used? for the modeling workflow.