A data acquisition framework for runoff prediction in ungauged basins - Runoff Prediction in Ungauged Basins: Synthesis across Processes, Places and Scales - page 33

Figure 3.5. Hydrological interpretation of
landscape features. Photo: © SAHRA at
University of Arizona.

are not easily inferred from topography and surface char-
acteristics alone. Where possible, field reconnaissance and
expert judgement can be invaluable for hydrological
assessment and, when coupled with remote analyses, allow
for more skilled interpretation and reading of the hydro-
logical landscape ( Figure 3.5 ). Field visits allow for com-
parison of the PUB catchment to similar gauged
catchments or heavily researched and more completely
understood catchments, thereby allowing transfer of the
'

environment. A landscape with wet vegetation types across
most landscape positions indicates widely available water
and a more stable soil moisture regime. Vegetation type,
while a function of many complex ecological and environ-
mental variable interactions, can be used as an indicator of
soil moisture stability/instability and rooting depth water
availability. For example, Mediterranean vegetation indi-
cates seasonally available water, while sagebrush can indi-
cate low or non-growing seasonal water availability.
Stream channel characteristics can also help infer catch-
ment runoff dynamics. Catchment drainage density can be
an indicator of climate and geology. The connection
between cross-section form and river runoff can result in
a high degree of temporal and spatial regularity as
expressed in the at-a-site and downstream hydraulic geom-
etry relationships (Mejia and Reed, 2011 ). Scoured chan-
nels and floodplains indicate high flows and runoff
magnitude, while streambed sediment characteristics and
morphology can inform estimation of stream power and
runoff magnitude when coupled with stream slope meas-
ures (Trevisani et al., 2010 ). Bankfull runoff estimation
can be used as an indicator of the size of peak runoff,
whereas in-channel and near-channel vegetation persist-
ence/species can inform interpretation of likely flow stabil-
ity and riparian corridor water table dynamics.
Runoff mechanisms can also be inferred by combining
previously described remote and local observations. Ero-
sional features across landscape positions can indicate the
magnitude, frequency and spatial extent of overland flow.
Locations of overland flow indicators can also suggest
infiltration excess or saturated overland flow processes.

individuals or teams pos-
sess from previous experience. This remotely sensed and
field visit derived similarity analysis relies on experience-
derived intuition and expert judgement. Interviews
with those possessing local knowledge and experienced
interpretation of the landscape can help determine or
select appropriate models and representation of dominant
hydrological processes operating in a catchment

hydrological knowledge library '

to

improve PUB.
Bedrock geological characteristics (e.g., weathering
depth, porosity, faults, dip direction, etc.) and soil depths
provide information about the likelihood and magnitude of
subsurface storage and geological and soil zone contribu-
tions to runoff. Additionally, catchment slope and flow
path lengths, in connection with forcing information, can
be used to infer likely runoff responsiveness (flashiness of
the hydrological system). Vegetation characteristics both
reflect and modify long-term hydrological dynamics. For
example, dry upland vegetation and wet alluvial vegetation
imply deeper groundwater and flow paths that could sus-
tain runoff during low precipitation time periods. They also
suggest transient soil moisture availability in the upland