A watershed average slope value is often needed in some hydrologic calculations, for example, Time of Concentration (TOC) estimation using NRCS Lag Time Method. The slope tool in AcrGIS or…
A watershed average slope value is often needed in some hydrologic calculations, for example, Time of Concentration (TOC) estimation using NRCS Lag Time Method. The slope tool in AcrGIS or…
A DEM, before it can be used for watershed delineation, often needs to be reconditioned and pre-processed by “filling” any depressions or sinks (an area lower than its surroundings) to…
TauDEM, developed by Utah State University is a set of tools to extract and analyze hydrologic information from topography as represented by a DEM. TauDEM is a set of standalone command…
In HEC-RAS 2D, the terrain created from LiDAR DEM often does not have enough details for areas located within a river channel. For better modeling purpose, normally a river bathymetry…
Often it is necessary to re-condition a DEM by burning streams or building walls to force a watershed to be delineated with known streams or boundaries (example: NHD streams or…
When performing a watershed delineation in GIS, a DEM usually needs to be pre-processed by "filling" any depressions or sinks (an area lower than its surroundings) to create a hydraulically…
In addition to delineating watersheds (drainage basins) upstream of one or more outlet points using WhiteboxTools' Watershed and UnnestBasins tools as illustrated in this post, WhiteboxTools has three other tools…
The SCS Curve Number (CN) is used to quantify infiltration loss during runoff calculation. As illustrated in Figure 1, a curve number should be determined by soil (Hydrologic Soil Groups, or…
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…