A “nested” design storm distribution, such as SCS Type Type I, IA, II, and III, or the frequency storm in HEC-HMS, is an artificial rainfall distribution using precipitation depth-duration-frequency data.…
A “nested” design storm distribution, such as SCS Type Type I, IA, II, and III, or the frequency storm in HEC-HMS, is an artificial rainfall distribution using precipitation depth-duration-frequency data.…
Historically Probable maximum precipitation (PMP) rainfall depths for spillway design were estimated using NOAA procedure and methodology such as HMR 51 and HMR 52. However, since HMR 51 and HMR…
Combined scale factor (CSF) is introduced in this post as well as the difference between ground coordinates (surface coordinates) and grid coordinates. As explained in the post, in a GIS…
The earth surface is irregular and curvy. To describe the earth surface mathematically, an ellipsoid is defined to approximate the bumpy earth surface, or more accurately a datum based on…
HEC-GridUtil is tool developed by USACE Hydrologic Engineering Center to manage and view gridded data stored in DSS files. The Post 1 of 2 here demonstrates on how to start…
Gridded data, either a static single grid or time series grids/grid set, can be imported and stored in HEC-DSS files using Vortex or HMS Gridded data importer. HEC-DSSVue is a…
Historical hourly or daily precipitation data in gridded format can be imported into a HEC DSS file used by HEC-HMS as time series gridded dataset or gridsets. The commonly available…
NOAA Atlas 14 provides the latest official U.S. precipitation frequency (PF) estimates for various durations and frequencies with lower and upper bounds of the 90% confidence interval. Refer to Post…
Two calibration methods are available in HEC-HMS: semi-automatic calibration using computation points and automatic calibration using optimization trial runs. This post is to focus on calibration by optimization trial runs.…
Two calibration methods are available in HEC-HMS: semi-automatic calibration using computation points and automatic calibration using optimization trial runs. This post is to focus on computation point calibration. Calibration by…