Geoscience Reference
In-Depth Information
Traces of pipes
N
Drainage
network
Agri Valley
0
200
m
Figure 11.10
Patterns of pipes mapped in the Agri basin, southern Italy by Farifteh and Soeters (1999).
conditions (James and Roulet, 2007). Thus, a spec-
trum of approaches and understandings of hydrological
connectivity has resulted from research conducted in dif-
ferent environments.
Current debates around hydrogeomorphic connectiv-
ity have centred on quantifying indices of hydrological
connectivity (Troch
et al.
, 2009; Antoine, Javaux and
Bielders, 2009) and investigating how these vary between
catchments. Studies can be divided into those deriving
pathways from topography (e.g. Lane, Reaney and Heath-
waite, 2009; Lesschen, Schoorl and Cammeraat, 2009;
Tetzlaff
et al.
, 2009) (in a similar vein to using topo-
graphic wetness indices to predict variable source area
understandings informed by water infiltration and trans-
fer at the plot or catchment scale (Buda
et al.
, 2009) and
occasionally by bringing these two approaches together
(Jensco
et al.
, 2009; Meerkerk, van Wesemael and Bellin,
2009).
A key soil variable that modifies the connectivity of
overland flow is the surface roughness. Surface roughness
is complex because it operates at a number of spatial scales
and can be highly dynamic. For instance, plough furrows
are relatively large and influence flow pathways (
form
roughness
; see Kirkby, Bracken and Reaney, 2002) and
individual stones and soil aggregates can be larger than
the flow depth (
grain roughness
), yet on the other hand