NAME
r.hazard.flood - Fast procedure to detect flood prone areas.
KEYWORDS
raster,
hydrology
SYNOPSIS
r.hazard.flood
r.hazard.flood --help
r.hazard.flood map=elevation flood=flood mti=MTI [--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
- --overwrite
- Allow output files to overwrite existing files
- --help
- Print usage summary
- --verbose
- Verbose module output
- --quiet
- Quiet module output
- --ui
- Force launching GUI dialog
Parameters:
- map=elevation [required]
- Name of elevation raster map
- flood=flood [required]
- Name of output flood raster map
- mti=MTI [required]
- Name of output MTI raster map
- Name of the output Modified Topographic Index (MTI) raster map
r.hazard.flood is an implementation of a fast procedure to detect
flood prone areas. It is based on a simple procedure that exploits the
correlation between flood exposure and a Modified Topographic Index (MTI),
calculated on the basis of the DTM and strongly influenced by the resolution
of this latter.
Before running the program, the region should be aligned perfectly with the
input map. The cell size taken in consideration is the one specified in the
region settings. If it doesn't match with the elevation map, the result is
nonsense.
Note that this program only supports projected coordinate systems, LatLong
is not supported.
The availability of new technologies for the measurement of surface
elevation has addressed the lack of high resolution elevation data, and
this has led to an increase in the attraction of DEM-based automated
procedures for hydrological applications including the delineation of
floodplains. In particular, the exposure to flooding may be delineated
quite well by adopting a modified topographic index (TIm) computed from
a DEM. The comparison between TIm and flood inundation maps (obtained
from hydraulic simulations) shows that the portion of a basin exposed to
flood inundation is generally characterized by a TIm higher than a given
threshold, tau. This allows the development of a simple procedure for
the identification of flood prone areas that requires only two parameters
for the calibration: the threshold tau and the exponent of TIm. Because
the topographic index is sensitive to the spatial resolution of the digital
elevation model, the threshold is automatically determinated from the cellsize.
The proposed procedure may help in the delineation of flood prone areas
especially in basins with marked topography. The method is sensitive to the
DEM resolution, but a cell size of ~100m is sufficient to reach good
performances for the catchments investigated here. The procedure is also
tested adopting DEMs from different sources, such as the shuttle radar
topography mission (SRTM) DEM, ASTER GDEM, and national elevation data.
This experiment highlights the reliability with the SRTM DEM for the
delineation of flood prone areas. A useful relationship between model parameters
and the reference scale of the DEM was also obtained providing a strategy
for the application of this method in different contexts.
The use of the modified topographic index should not be considered as an
alternative to standard hydrological-hydraulic simulations for flood mapping,
but it may represent a useful and rapid tool for a preliminary delineation
of flooding areas in ungauged basins and in areas where expensive and time
consuming hydrological-hydraulic simulations are not affordable or economically
convenient.
g.region raster=elevation -ap
r.hazard.flood map=elevation flood=flood mti=mti
r.area
Di Leo M., Manfreda S., Fiorentino M., An automated procedure for
the detection of flood prone areas: r.hazard.flood, Geomatics Workbooks
n.10, 2011.
(PDF)
Manfreda S., Di Leo M., Sole A., Detection of Flood Prone Areas using
Digital Elevation Models, Journal of Hydrologic Engineering,
(10.1061/(ASCE)HE.1943-5584.0000367), 2011.
Margherita Di Leo (dileomargherita AT gmail DOT com)
SOURCE CODE
Available at:
r.hazard.flood source code
(history)
Latest change: Monday Jan 30 19:52:26 2023 in commit: cac8d9d848299297977d1315b7e90cc3f7698730
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