QEHT Engineering Hydrology
Road-drainage and catchment hydrology from a DEM, computed entirely inside QGIS: no external executables, no extra Python packages.
QEHT turns a DEM and a road centreline into the hydrology a drainage
designer needs at every crossing, with every computation running inside
QGIS using only NumPy and the GDAL bindings that QGIS ships. It never
starts another process, so it works on managed workstations where
security software blocks the SAGA, GRASS, TauDEM or WhiteboxTools
providers, and it needs no pip installation.
Terrain and drainage: DEM preparation and audits (nearest-neighbour
resampling, undeclared NoData), depression filling, D8 flow direction with
Barnes (2014) or toward-lower flat resolution, flow accumulation, streams
with Strahler order, catchments, longest flow paths and the four slope
measures used in design.
Road drainage: crossing candidates along the alignment with chainage,
burning culverts through embankments, ground profile, a drainage-coverage
check (missing crossings, sags, flat stretches) with proposed crossings,
a check against mapped rivers, floodplain width and channel sections at
crossings, corridor auto-clip for national DEMs, and DEM-error uncertainty
of area and time of concentration at each crossing.
Catchment parameters: soils and USLE K from SOTWIS, SoilGrids or any soil
map; hydrologic soil groups, curve numbers and Rational C; rainfall zones
and mean annual rainfall; land-cover scenarios; time of concentration by
Kirpich, Kerby-Kirpich, SCS lag, TR-55 and Bransby-Williams with validity
flags; erosion indices, RUSLE and side-drain siltation screening.
Outputs: a one-click pipeline with a fixed folder layout, an HTML run
report, a one-row-per-crossing characteristics table, raster quicklooks,
KMZ and XLSX exports, and a self-describing GeoPackage (design hydrology
package) for design software. Proxies and estimates are labelled as such
in every output; no engineering value is invented.
Licensed under the GNU General Public License version 2 or later.