02 - Sub-basins

Result subdivision into sub-basins applying geomorphological analysis with GEOframe tools. The standard GEOframe procedure involves the use of concatenated *.sim files which, starting from a DEM, allow the definition of sub-basins based on geomorphological characteristics. The procedure is summarized as follow: • Carver and Pitfiller: These are preliminary tools that help eliminate uncertainties in the DEM and prepare it for geomorphological investigation. • Flow directions : It determines drainage directions for each cell of the modified raster (pitfiller). • Drain directions: It recalculates the directions to minimize the deviation from the actual flow and returns the map of contributing areas. • Mark outlets: It marks the cells that drain outside the domain. • Water outlet: It defines the mask of the catchment, given the coordinates of the closure point. • Cut out: It defines the mask of the catchment, given the coordinates of the closure point. • Skyview factor: The function returns a raster map of numbers between 0 and 1. Each cell of this raster represents the Skyview Factor value, that is, a value representing the portion of the visible sky. The values tending to zero describe points in the region of interest where the sky is poorly visible or completely obstructed while the maximum, the value 1, represents a point of complete 360° visibility. • Extract network: It extracts the final hydrographic network by imposing a threshold on the contributing area (in this case, it corresponds to 50). • Net attributes builder: It vectorizes the extracted network. The tool equips it with all the attributes to reorder and define it geometrically. • Net numbering: It extracts the raster map of the subbasins by imposing a threshold area (in this case, it was chosen a 3 km2 threshold). • GEOframe Input builder: It prepares the structure of the model input data. For each subbasin, a folder containing the results of the geomorphological analysis related to the HRU is created. Naming conventions: dtm_n°.asc for example, dtm_35.asc, number varies based on the sub-basin which it refers to.