Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2018-54
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
08 Mar 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
The influence of long-term changes in canopy structure on rainfall interception loss: a case study in Speulderbos, the Netherlands
César Cisneros Vaca, Christiaan van der Tol, and Chandra Prasad Ghimire Faculty of Geo-information and Earth Observation (ITC), University of Twente, Enschede, P.O. Box 217, 7500 AE, the Netherlands
Abstract. The evaporation of intercepted water by forests is a significant contributor to both the water and energy budget of the Earth. In many studies, a discrepancy in the water and energy budget is found: the energy that is needed for evaporation is larger than the available energy supplied by net radiation. In this study, we analyse the water and energy budget of a mature Douglas-fir stand in the Netherlands, for the two growing seasons of 2015 and 2016. Based on the wet-canopy water balance equation for these two growing seasons, derived interception losses were estimated to be 37 % and 39 % of gross rainfall, respectively.

We further scrutinized eddy covariance energy balance data from these two consecutive growing seasons and found the average evaporation rate during wet canopy conditions was 0.20 mm h−1. The source of energy for this wet-canopy evaporation was net radiation (35 %), a negative sensible heat flux (45 %) and a negative energy storage change (15 %). This confirms that the energy for wet-canopy evaporation is extracted from the biomass as well as the atmosphere.

Moreover, the measured interception loss at the forest was similar to that measured at the same site years before (I = 38 %), when the forest was younger (29 years old, vs 55 years old in 2015). At that time, the forest was denser and had a higher canopy storage capacity (2.4 mm then vs 1.90 mm in 2015), but the aerodynamic conductance was lower (0.065 m s−1 then vs 0.105 m s−1 in 2015), and therefore past evaporation rates were lower than evaporation rates found in the present study (0.077 mm h−1 vs 0.20 mm h−1 in 2015). Our findings emphasize the importance of quantifying downward sensible heat flux and heat release from canopy biomass in tall forest in order to improve the quantification of evaporative fluxes in wet canopies.

Citation: Cisneros Vaca, C., van der Tol, C., and Prasad Ghimire, C.: The influence of long-term changes in canopy structure on rainfall interception loss: a case study in Speulderbos, the Netherlands, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-54, in review, 2018.
César Cisneros Vaca et al.
César Cisneros Vaca et al.
César Cisneros Vaca et al.

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