11. Extract and connect attributes to the subbasins

Attributes can be added to the subbasins from datasets in shapefiles (point/polygons) or gridded/rasters (.bil format).
The added attributes will be found in the attribute file of the exported subbasin shapefile or the so called HYSS file.
The datasets can be spatially linked to the subbasins by a few different GIS methods:

Point layers (nearest or inside)

Polygons (mean, missing, nearest, inside, first centerhit, largest centerhit, smallest centerhit, target, outlet, sum, multiple, classes, adjclasses)

Grid (mean, nearest, min, max, median, stdev, sum, missing, zones, classes, adjclasses, relief ratio).

NOTE (1): Test the methods to be sure you get the supposed outcome.
NOTE (2): HYPE uses -9999 for missing values. If no data can be extracted for a certain subbasin it will get this value by default.
NOTE (3): Remember that the used files (shapefiles/grids) must be in the same projection as the WHIST database you are using and the grids must be in .bil format.

11.1 General description
11.2 Link information from a point layer
11.2 Link information from polygons
11.3 Link information from grid

11.1 General description

Go to HYDRO/Data
Click the button "manage data connection"
Choose the type of data file to extract (polygon/point/grid)
Choose the field from the data set attributes that will be connected.
Choose method to link/extract the data, give the attribute a name, click on "create new". The Name will now appear to the right under "Existing list".
Continue with all dataconnections you want to add to the attribute table and click OK
Select the basins you want to connect the data to
Click on the button "create for selected basins" and choose the once you want to calculate/recalculate in the next window and then OK.
If you want to remove data connections: select the once you want to remove in the "Existing list" and click on "remove". If you want to remove all data connections: click on "clear".
When you Export subbasin shapefile and/or HYSS file the extracted data will all be added after the already existing default columns

11.2 Link information from a point layer

There are two ways to link data from a point layer to the subbasins:

nearest
inside

Red dots are observation points, X are subbasin centerpoints, orange lines show links to nearest observation point, yellow show links to an observation point located inside the subbasin.

You can choose which attribute from the linked file you would like to link. It is possible to link several attributes from the same file.

See 11.1 General description for all steps from data to output.

11.2 Link information from polygons

There several ways to link data from a point layer to the subbasins:

MEAN
MISSING
NEAREST
INSIDE
FIRST CENTERHIT
LARGEST CENTERHIT
SMALLEST CENTERHIT
TARGET
OUTLET
SUM
MULTIPLE
CLASSES
ADJCLASSES

You can choose which attribute from the linked file you would like to link. It is possible to link several attributes from the same file.

See 11.1 General description for all steps from data to output.

11.3 Link information from grid

There are several ways to extract data from a grid to the subbasins. The choice usually depends on the nature of the gridded data, for example:

From a DEM you can extract different elevation statistics for the subbasins:

MEAN
MEDIAN
MIN
MAX
STDEV
RELIEF RATIO ((ELEVmedian - ELEVmin) / (ELEVmax - ELEVmin))

From a grid with different classes (e.g. SLC (soil and landuse classes) or zones you can extract the fraction of each class/zone belonging to each subbasin.

CLASSES (e.g. SLC_1, SLC_2, SLC_3...)

From DEM and DIR you can extract the slope of the subbasin.

SLOPE

From SLC and DEM you can extract the deviation of the subbasin mean elevation for each class in the subbasin (adjclasses) which will give you the attributes called DHSLC_1, DHSLC_2, DHSLC_3, etc (corresponding to SLC_1, SLC_2, SLC_3, etc)

ADJCLASS

From a population grid you ca sum up the number of citizens within the subbasin

See 11.1 General description for all steps from data to output.