GHR.- Tools for hydraulic modeling by combining Hec-Ras, Grass and other possible GIS applications.
The GHR application has been designed to perform one-dimensional hydraulic calculations of river reaches with the Hec-Ras model (http://www.hec.usace.army.mil/software/hec-ras). Its main objective is to facilitate the geometric definition of the section, using a digital terrain model (DTM) to obtain and operate with water and soil surface heights.
Besides the Hec-Ras application, the basis of GHR is the GIS (Geographic Information System) Grass (https://grass.osgeo.org/). However, another GIS can be used in some tasks.
The application works on a DTM, in raster format (matrix), as one of the main sources of information. It offers two possibilities:
With the DTM and together with vectorial GIS layers of longitudinal axes and plants of the cross-sections to the channel, it generates a file (SDF type) that contains the hydraulic characterization of the river section, including the vertical definitions of the cross-sections, whose altitudes are obtained from the DTM.
From an SDF file exported from Hec-Ras, it generates the vectorial layers of axes and sections and, if it includes the calculation results, it also generates the flood areas. The application can also generate the GIS layers of the flood zone boundaries included in the SDF, but also allows them to be modified by the user to condition the interpolation of the water flows in the terrain, all using the MDT.
Other solutions can be found that offer utilities that satisfy GHR. Among others, the following can be mentioned:
Hec-GeoRas: "HEC-GeoRAS is a set of procedures, tools and utilities for processing geospatial data in ArcGIS using a graphical user interface (GUI)" ( http://www.hec.usace.army.mil/software/hec-georas).
RiverGIS. "RiverGIS is a QGIS plugin for creating HEC-RAS flow model geometry from spatial data. The functionality is similar to that of HEC-GeoRAS. For data storage and spatial operations you need a PostGIS" database (http://www.rivergis.com).
RiverGIS is based on the free software SIG QGIS (https://www.qgis.org/), but requires a PostGIS database (http://www.postgis.net). Hec-GeoRas is based on the ArcGIS application (http://www.arcgis.com), which is commercial.
Both are more complete and therefore more complex than GHR, but GHR is designed to provide a fast and efficient solution for one-dimensional modeling.
GHR only depends on Grass and uses the Python interpreter associated with it, so it has no special requirements for the installation.
Some tasks that are done with GHR can also be performed from Hec-Ras itself. But the use of specialized GIS tools is considered advantageous from many points of view. And GHR allow the manual modification of inundation areas.