The standard hydrologic grid (SHG) is a grid system developed by USACE Hydrologic Engineering Center (HEC) to cover the conterminous United States for hydrologic modeling purpose in HEC-HMS. SHG is…
The standard hydrologic grid (SHG) is a grid system developed by USACE Hydrologic Engineering Center (HEC) to cover the conterminous United States for hydrologic modeling purpose in HEC-HMS. SHG is…
HEC-HMS frequency storm is a type of "nested" rainfall distributions, which can be built by using NOAA Atlas 14 precipitation depth data. If you want to reduce point precipitation depths…
Similar to SCS Type I, IA, II, and III or other NRCS "nested" rainfall distributions, HEC-HMS frequency storm method provides a way to construct your own "nested" rainfall distributions using…
This post (3 of 3) is an instruction of combining Land Cover Raster file and HSG Raster file to create a CN raster file for calculating an area-weighted average CN…
Hydrologic Soil Group Data (A, B, C, and D) is an important soil property which impacts the soil infiltration rates and runoff potential. Soils were originally assigned to hydrologic soil…
The SCS (NRCS) Curve Number is used to quantify infiltration loss during runoff calculation. As illustrated in Figure 1, the CN is determined by both soil types (Hydrologic Soil Groups,…
HEC-HMS has the capability to estimate hydrology parameters for watersheds delineated. This post is to demonstrate these functions. The Bear Creek Watershed was delineated in Post 1 of 3 and…
After a watershed has been delineated using HEC-HMS GIS tools, the subbasins and reaches can be further refined using HEC-HMS merge and split functions. Five subbasins and two reaches were…
The new HEC-HMS published around 2020 has some useful GIS tools to delineate a watershed using terrain data. Unlike HEC-GeoHMS, these standalone GIS commands are an integral part of HEC-HMS…