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| Titel |
Modelling rainfall interception by forests: a new method for estimating the canopy storage capacity |
| VerfasserIn |
Fernando Pereira, Fernanda Valente, Cristina Nóbrega |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107001
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| Publikation (Nr.) |
 EGU/EGU2015-6687.pdf |
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| Zusammenfassung |
| Evaporation of rainfall intercepted by forests is usually an important part of a catchment
water balance. Recognizing the importance of interception loss, several models of the process
have been developed. A key parameter of these models is the canopy storage capacity (S),
commonly estimated by the so-called Leyton method. However, this method is somewhat
subjective in the selection of the storms used to derive S, which is particularly critical when
throughfall is highly variable in space. To overcome these problems, a new method for
estimating S was proposed in 2009 by Pereira et al. (Agricultural and Forest Meteorology,
149: 680-688), which uses information from a larger number of storms, is less sensitive to
throughfall spatial variability and is consistent with the formulation of the two most widely
used rainfall interception models, Gash analytical model and Rutter model. However,
this method has a drawback: it does not account for stemflow (Sf). To allow a
wider use of this methodology, we propose now a revised version which makes the
estimation of S independent of the importance of stemflow. For the application of this
new version we only need to establish a linear regression of throughfall vs. gross
rainfall using data from all storms large enough to saturate the canopy. Two of the
parameters used by the Gash and the Rutter models, pd (the drainage partitioning
coefficient) and S, are then derived from the regression coefficients: pd is firstly
estimated allowing then the derivation of S but, if Sf is not considered, S can be
estimated making pd= 0. This new method was tested using data from a eucalyptus
plantation, a maritime pine forest and a traditional olive grove, all located in Central
Portugal. For both the eucalyptus and the pine forests pd and S estimated by this new
approach were comparable to the values derived in previous studies using the standard
procedures. In the case of the traditional olive grove, the estimates obtained by
this methodology for pd and S allowed interception loss to be modelled with a
normalized averaged error less than 4%. Globally, these results confirm that the method is
more robust and certainly less subjective, providing adequate estimates for pd and
S which, in turn, are crucial for a good performance of the interception models. |
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