Geoscience Reference
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Fig. 11.7 Maximal extent of the saturated areas and distribution of subsurface outflow points at the peak
discharge rate of a 195 mm storm in September 1980 on a steep 0.022 km
2
catchment within the source
region of the Tama River. The saturated area occupied roughly 3.3% of the basin area and the area
shown represents roughly one quarter of the basin area. (From Tanaka
et al.
, 1981.)
to the more specific view that, while individual macropore segments are usually shorter
than 0.5 m, they tend to self-organize, as wetness increases, into larger flow systems with
such preferential flow connections between them as buried pockets of organic material
and loose soil, small depressions of bedrock substrate, and fractures in the weathered
bedrock.
Chemical analysis of measurements on a 0.75 ha forested first-order catchment in
the sub-Andean foreland basin of Peru by Elsenbeer
et al
. (1995b) indicated that the
stormflow response is dominated by event water. This water traveled to the stream
channel as a combination of overland flow and through pipes. Some pipe flow reached
the stream directly, but some emerged to the surface before reaching the stream. The
overland flow was thus generated by emerging pipe flow and directly by the rain.
This made them observe that, from the perspective of the catchment, the distinction
between pipe flow and overland flow is meaningless, as both mechanisms produced event
water.
From observations in a semiaridpine forest in New Mexico, Newman
et al
. (1998)
concluded that most of the lateral subsurface flow takes place in the B horizon through
macropores. Thus throughout most of the year, the soil profile behaves like a two-domain
