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-2018-225
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
02 May 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
Toward continental hydrologic–hydrodynamic modeling in South America
Vinícius A. Siqueira1, Rodrigo C. D. Paiva1, Ayan S. Fleischmann1, Fernando M. Fan1, Anderson L. Ruhoff1, Paulo R. M. Pontes2, Adrien Paris3,4,a, Stéphane Calmant3, and Walter Collischonn1 1Instituto de Pesquisas Hidráulicas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, 91501-970, Brazil
2Instituto Tecnológico Vale (ITV), Belém, 66055-090, Brazil
3LEGOS, Université de Toulouse, CNRS, CNES, IRD, UPS, Toulouse, France
4GET, Toulouse, France
anow at : Collecte Localisation Satellite (CLS), Ramonville-Saint-Agne, 31520, France
Abstract. Providing reliable estimates of streamflow and hydrological fluxes is a major challenge for water resources management over national and transnational basins in South America. Global hydrological models and land surface models are a possible solution to simulate the terrestrial water cycle at the continental scale, but issues on parameterization and limitations in representing lowland river systems put into question their utility for basin-scale analysis and to deliver daily discharges to meet local needs. In an attempt to overcome such limitations, we extended a regional, fully coupled hydrologic–hydrodynamic model (MGB) to the continental domain of South America and assessed its performance using daily river discharges, water levels from independent sources (in situ, satellite altimetry), estimates of terrestrial water storage (TWS) and evapotranspiration (ET) from remote sensing and other available global datasets. In addition, river discharges were compared with outputs from global models acquired through the eartH2Observe project (HTESSEL/CaMa-Flood, LISFLOOD and WaterGAP3), providing the first cross-scale assessment (regional/continental × global models) that makes use of spatially consistent daily discharge data. A satisfactory representation of discharges and water levels was obtained (NSE > 0.6 in 55 % of the cases) and MGB was able to capture patterns of seasonality and magnitude of TWS and ET especially over the largest basins of South America. Continental-scale modeling significantly improved discharge estimates when compared with global models, which resulted in a large number of gauges with negative (or close to 0) NSE values. Models were largely affected by positive bias mainly over East/Northeast Brazil and Argentina as well as over regions of Sao Francisco and Parnaiba basins, while major issues on flow timing were observed in regions affected by floodplain processes such as the Amazon, La Plata, Tocantins–Araguaia, Orinoco and Magdalena basins. We state that efforts in calibrating rainfall-runoff parameters within large basins are necessary to simulate daily river discharges appropriately in this continent, but implementing a hydrodynamic routing component is also important. We hope that our study provides further insights about hydrological simulation in South America, helping to reduce the gap between global and regional hydrological modeling communities.
Citation: Siqueira, V. A., Paiva, R. C. D., Fleischmann, A. S., Fan, F. M., Ruhoff, A. L., Pontes, P. R. M., Paris, A., Calmant, S., and Collischonn, W.: Toward continental hydrologic–hydrodynamic modeling in South America, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2018-225, in review, 2018.
Vinícius A. Siqueira et al.
Vinícius A. Siqueira et al.
Vinícius A. Siqueira et al.

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Short summary
Providing reliable estimates of water fluxes at the continental scale is a challenging task. We extended a regional hydrological model to the entirety of South America and assessed its performance using multiple observations. We found that continental-scale modeling is promising and significantly improves river discharges in comparison to estimates from global models. Efforts in model calibration and improved river model physics are necessary to simulate daily river discharges in this continent.
Providing reliable estimates of water fluxes at the continental scale is a challenging task. We...
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