Can climate variability information constrain a hydrological model for an ungauged Costa Rican catchment? |
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Authors: | Beatriz Quesada‐Montano Ida K Westerberg Diana Fuentes‐Andino Hugo G Hidalgo Sven Halldin |
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Institution: | 1. Department of Earth Sciences, Uppsala University, Uppsala, Sweden;2. Centre for Geophysical Research, University of Costa Rica, San Jose, Costa Rica;3. Centre for Natural Disaster Science, Uppsala, Sweden;4. IVL Swedish Environmental Research Institute, Stockholm, Sweden;5. School of Physics, University of Costa Rica, San Jose, Costa Rica |
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Abstract: | Long‐term hydrological data are key to understanding catchment behaviour and for decision making within water management and planning. Given the lack of observed data in many regions worldwide, such as Central America, hydrological models are an alternative for reproducing historical streamflow series. Additional types of information—to locally observed discharge—can be used to constrain model parameter uncertainty for ungauged catchments. Given the strong influence that climatic large‐scale processes exert on streamflow variability in the Central American region, we explored the use of climate variability knowledge as process constraints to constrain the simulated discharge uncertainty for a Costa Rican catchment, assumed to be ungauged. To reduce model uncertainty, we first rejected parameter relationships that disagreed with our understanding of the system. Then, based on this reduced parameter space, we applied the climate‐based process constraints at long‐term, inter‐annual, and intra‐annual timescales. In the first step, we reduced the initial number of parameters by 52%, and then, we further reduced the number of parameters by 3% with the climate constraints. Finally, we compared the climate‐based constraints with a constraint based on global maps of low‐flow statistics. This latter constraint proved to be more restrictive than those based on climate variability (further reducing the number of parameters by 66% compared with 3%). Even so, the climate‐based constraints rejected inconsistent model simulations that were not rejected by the low‐flow statistics constraint. When taken all together, the constraints produced constrained simulation uncertainty bands, and the median simulated discharge followed the observed time series to a similar level as an optimized model. All the constraints were found useful in constraining model uncertainty for an—assumed to be—ungauged basin. This shows that our method is promising for modelling long‐term flow data for ungauged catchments on the Pacific side of Central America and that similar methods can be developed for ungauged basins in other regions where climate variability exerts a strong control on streamflow variability. |
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Keywords: | Central America climate variability hydrological model process constraints uncertainty ungauged basins |
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