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Titel |
Influence of soil and climate on root zone storage capacity |
VerfasserIn |
Tanja de Boer-Euser, Hilary McMillan, Markus Hrachowitz, Hessel Winsemius, Hubert Savenije |
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 |
250124543
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Publikation (Nr.) |
EGU/EGU2016-3993.pdf |
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Zusammenfassung |
The catchment representative root zone storage capacity (Sr), i.e. the plant available soil
water, is an important parameter of hydrological systems. It does not only influence the runoff
from catchments, by controlling the partitioning of water fluxes but it also influences the
local climate, by providing the source for transpiration. Sr is difficult to observe at
catchment scale, due to heterogeneities in vegetation and soils. Sr estimates are
traditionally derived from soil characteristics and estimates of root depths. In contrast, a
recently suggested method allows the determination of Sr based on climate data, i.e.
precipitation and evaporation, alone (Gao et al., 2014). By doing so, the time-variable size
of Sr, is explicitly accounted for, which is not the case for traditional soil based
methods. The time-variable size of Sr reflects root growth and thus the vegetation’s
adaption to medium-term fluctuations in the climate. Thus, we tested and compared Sr
estimates from this ’climate based method’ with estimates from soil data for 32
catchments in New Zealand. The results show a larger range in climate derived Sr than
in soil derived Sr. Using a model experiment, we show that a model using the
climate derived Sr is more accurately able to reproduce a set of hydrological regime
signatures, in particular for humid catchments. For more arid catchments, the two
methods provide similar model results. This implies that, although soil database
information has some predictive power for model soil storage capacity, climate
has a similar or greater control on Sr, as climate affects the evolving hydrological
functioning of the root zone at the time scale of hydrological interest. In addition, Sr
represents the plant available water and thus root surface, volume and density, and
is therefore a more complete descriptor of vegetation influence on water fluxes
than mere root depth. On balance, the results indicate that climate has a higher
explanatory power than soils for catchment representative root zone storage capacity. |
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