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| Titel |
Modelling the hydrological behaviour of a coffee agroforestry basin in Costa Rica |
| VerfasserIn |
F. Gómez-Delgado, O. Roupsard, G. Maire, S. Taugourdeau, A. Pérez, M. Oijen, P. Vaast, B. Rapidel, J. M. Harmand, M. Voltz, J. M. Bonnefond, P. Imbach, R. Moussa |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 15, no. 1 ; Nr. 15, no. 1 (2011-01-28), S.369-392 |
| Datensatznummer |
250012609
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| Publikation (Nr.) |
 copernicus.org/hess-15-369-2011.pdf |
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| Zusammenfassung |
| The profitability of hydropower in Costa Rica is affected by soil erosion
and sedimentation in dam reservoirs, which are in turn influenced by land
use, infiltration and aquifer interactions with surface water. In order to
foster the provision and payment for Hydrological Environmental Services
(HES), a quantitative assessment of the impact of specific land uses on the
functioning of drainage-basins is required. The present paper aims to study
the water balance partitioning in a volcanic coffee agroforestry micro-basin
(1 km2, steep slopes) in Costa Rica, as a first step towards evaluating
sediment or contaminant loads. The main hydrological processes were
monitored during one year, using flume, eddy-covariance flux tower, soil
water profiles and piezometers. A new Hydro-SVAT lumped model is proposed,
that balances SVAT (Soil Vegetation Atmosphere Transfer) and basin-reservoir
routines. The purpose of such a coupling was to achieve a trade-off between
the expected performance of ecophysiological and hydrological models, which
are often employed separately and at different spatial scales, either the
plot or the basin. The calibration of the model to perform streamflow
yielded a Nash-Sutcliffe (NS) coefficient equal to 0.89 for the year 2009,
while the validation of the water balance partitioning was consistent with
the independent measurements of actual evapotranspiration (R2 = 0.79,
energy balance closed independently), soil water content (R2 = 0.35) and
water table level (R2 = 0.84). Eight months of data from 2010 were used
to validate modelled streamflow, resulting in a NS = 0.75. An uncertainty
analysis showed that the streamflow modelling was precise for nearly every
time step, while a sensitivity analysis revealed which parameters mostly
affected model precision, depending on the season. It was observed that
64% of the incident rainfall R flowed out of the basin as streamflow and
25% as evapotranspiration, while the remaining 11% is probably
explained by deep percolation, measurement errors and/or inter-annual
changes in soil and aquifer water stocks. The model indicated an
interception loss equal to 4% of R, a surface runoff of 4% and an
infiltration component of 92%. The modelled streamflow was constituted by
87% of baseflow originating from the aquifer, 7% of subsurface
non-saturated runoff and 6% of surface runoff. Given the low surface
runoff observed under the current physical conditions (andisol) and
management practices (no tillage, planted trees, bare soil kept by weeding),
this agroforestry system on a volcanic soil demonstrated potential to
provide valuable HES, such as a reduced superficial displacement-capacity
for fertilizers, pesticides and sediments, as well as a streamflow
regulation function provided by the highly efficient mechanisms of aquifer
recharge and discharge. The proposed combination of experimentation and
modelling across ecophysiological and hydrological approaches proved to be
useful to account for the behaviour of a given basin, so that it can be
applied to compare HES provision for different regions or management
alternatives. |
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