Geoscience Reference
In-Depth Information
2.3.2 Data enrichment
The data enrichment process collects, for each edge
i
, the following infor-
mation:
•
S
i
: the Strahler order of the edge
i
•
L
i
: the total distance to the furthest source up hill
•
B
i
: the total number of branches up hill
The procedure is top-down: starting from one of the sources, the algorithm
follows the flow direction down hill, calculating
L
i
for each edge (
S
i
and
B
i
will not change until another edge is met). If the current edge
c
has two
fathers
a,b
, the values for
c
will be calculated as follows:
S
c
= max( S
a
, S
b
)
if S
a
!= S
b
S
c
= S
a
+1
otherwise
L
c
= max ( L
a
,L
b
) + length( c )
B
c
= max ( B
a
,B
b
) + 1
The next current edge will be one of the children of
c
. The algorithm
randomly chooses a source edge to start from: as a consequence it may
happen that when two edges meet, one of them has not been enriched yet.
In such a case the algorithm will pick another source and start the procedure
from there. The same happens if the current edge has not any child. The
process will end when all the edges have been enriched.
2.3.3 River course reconstruction
The procedure is bottom-up: starting from the drain with the highest
Strahler order, the algorithm follows the flow direction up hill choosing as
the next current edge one of the fathers edge of the current edge. The next
current edge is chosen after assigning a score to each father that depends
on the name of the edge, the IGMI hydrography class it belongs to (among
“very small”, “small”, “medium” and “big” river), the number
L
, the
number
B
and its width.
The scoring procedure will assign a higher score to a father edge if:
•
it has the same name of the current edge,
