What does it take to flood the Pampas? : lessons from a decade of strong hydrological fluctuations
Date
2015-01
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Abstract
While most landscapes respond to extreme rainfalls with increased liquid water outputs, very flat and poorly drained ones have little capacity to do this and their most common responses include (i) increased water storage leading to rising water tables and floods, (ii) increased evaporative water losses and, at high levels of storage, (iii) increased liquid water losses. The relative importance of these pathways were explored in the extensive plains of the Argentine Pampas, where two significant flood episodes (herein FE1 and FE2) occurred in 2000-2003 and 2012-2013. Focusing on two of the most flood-prone areas (Western and Lower Pampa, 60 000 km2 each), it was found that the surface water cover reached 31 and 19% during FE1 in each subregion, while FE2 covered up to 22 and 10%, respectively. From the spatiotemporal heterogeneity of the flood events, we distinguished 1) slow floods lasting several years when the water table is brought near the surface 16 following sustained precipitation excesses in groundwater-connected systems (Western Pampa), and "fast" floods triggered by surface water accumulation over the course of weeks to months, typical of a poor above-/belowground connectivity (Lower Pampa) or more generally when exceptionally-strong rain-falls overwhelm infiltration. Because of these different hydrological responses, precipitation and evapotranspiration were strongly linked in the Lower Pampa only, while the connection between water fluxes and storage was limited to the Western Pampa. In both regions, evapotranspirative losses (pathway (ii)) were strongly linked to flooded conditions as a regulatory feedback, while liquid water losses (pathway (iii)) remained negligible.
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Draft
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Journal Article (peer-reviewed)
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Keywords
FLOODING, PLAINS, ARGENTINA--PAMPAS, EVAPOTRANSPIRATION, HYDROLOGY, SOIL WATER BALANCE, STREAM FLOW, GROUNDWATER, PERIODICITY, RISK MANAGEMENT
Citation
Kuppel, S., Houspanoussian, J., Nosetto, M.D., & Jobbágy, E.G. (2015). What does it take to flood the Pampas? Lessons from a decade of strong hydrological fluctuations. Water Resources Research, 1-39.