GWAT is a Watershed Analysis Toolbox for QGIS, originally developed at the dept. of hydrology and hydraulics engineering of Geomeletitiki Consulting Engineers SA.
It is an opinionated tool, providing a specific methodology, compliant with the legal specifications of the Greek legislation, for the calculation of the hydrological parameters of a watershed. The functionality is split into 4 modules, executed in sequence:
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Preprocessing: The user provides the DEM of the watershed, and the tool calculates the filled DEM, flow directions and channel network. Watershed statistics are also produced.
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Hydrological Analysis: The user provides a pour point/drainage outlet, and the tool calculates the Curve Numbers (CN), topographic contours, SCS soil classes and COrine 2018 land cover classes. Statistics regarding the % coverage of different CNs, land cover classes etc are also produced. Note that this step relies on a WFS service for the soil and land cover maps, which currently restricts its application to Greece.
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Longest Flow Path: The tool calculates the longest flow path from the pour point to the watershed outlet. Also calculates the Elongation Ratio of the basin
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ICN Curves: A set of known Greek meteo stations is used to find the n nearest stations to the basin. Inverse Distance Gage Weighting (with respect to the basin's centroid) is then used to calculate the station parameters to be used in ICN curves.
The original goal of this plugin was to automate the workflow of calculating the hydrological parameters of a watershed, as per the Greek legislation. It is essentially a wrapper around some of SAGA's hydrological tools, and some custom python code to strealine the process.
- Ioannis Georgakis: Conception & process design
- Eleftheria Koutsimari: Testing, QA and debuging. The leading expert in the usage of the tool.
- Efstathios Lymperis: Development & maintenance
