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| Titel |
Impacts of rainfall features and antecedent soil moisture on occurrence of
preferential flow: A study at hillslopes using high-frequency monitoring |
| VerfasserIn |
Zhenyang Peng, Fuqiang Tian, Hongchang Hu |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250125676
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| Publikation (Nr.) |
 EGU/EGU2016-5288.pdf |
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| Zusammenfassung |
| In order to evaluate influences of rainfall features and antecedent soil moisture on
occurrence of preferential flow, a more than 2 years observation was conducted at
12 sites within a 7-km2 catchment, by applying the high-frequency monitoring
approach. Totally 65 rainfall events were selected to compare among sites, and
preferential flow was inferred when (i) responses of soil moisture did not follow
a linear sequence with depth, and (ii) penetration velocity of wetting front in at
least one horizon exceeded the threshold, which was set to be 5-10 times of the
saturated hydraulic conductivity of soil matrix at different depths. Results showed that
frequency of preferential flow was 40.7% in average, but varied from 17.9% to
74.3% among the sites. Correlations between the frequency and rainfall features,
i.e. rainfall amount, duration, maximum and average intensity, were well fitted by
logarithmic curves. Rainfall amount, which was most prominently correlated with
frequency (R2=0.93), was regarded as the dominant driving factor of preferential
flow, while average intensity was in second (R2=0.90). Antecedent soil moisture
was also significantly correlated with the frequency. However, this should largely
be attributed to the differences of soil moisture among sites, since varying range
of soil moisture at a specific site was not wide enough to influence the frequency
significantly. Further examination suggested that topography and surface cover
(dead leaves and humus) were the controlling factors of both infiltration amount and
occurrence of preferential flow, as water was more readily to infiltrate into soils and
preferential flow was more readily to occur when slope gradient was small and surface
cover was thick, while soil moisture was more likely to be a consequence of water
storage capacity, rather than an inducer of preferential flow. This knowledge could be
helpful in understanding the partitioning of surface runoff and infiltration, as well as
runoff processes in catchments with complex topography and underlying conditions. |
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