Deriving Hydrological Response Units (HRUs) using a Web Processing Service implementation based on GRASS GIS

QGIS releases equal to or newer than 0.7 can easily connected to GRASS GIS by means of a toolbox that provides a wide range of standard GRASS modules you can launch – albeit only on data coming from GRASS. This QGIS plugin is expandable through XML configurations describing the assignment of options and inputs for a certain module. But how about embedding a precise workflow where the several processes don’t consist of a single GRASS module by force? Especially for a sequence of dependent tasks it makes sense to merge relevant GRASS functionality into an own and encapsulated QGIS extension. Its architecture and development is tested and combined with the Web Processing Service (WPS) for remote execution using the concept of hydrological response units (HRUs) as an example. The results of this assay may be suitable for discussing and planning other wizard-like geoprocessing plugins in QGIS that also should make use of an additional GRASS server.