Coupling statistically downscaled GCM outputs with a basin-lake hydrological model in subtropical South America: evaluation of the influence of large-scale precipitation changes on regional hydroclimate variability

International audienceWe explore the reliability of large-scale climate variables, namely precipitation and temperature, as inputs for a basin-lake hydrological model in central Argentina. We used data from two regions in NCEP/NCAR reanalyses and three regions from LMDZ model simulations forced with observed sea surface temperature (HadISST) for the last 50 years. Reanalyses data cover part of the geographical area of the Sali-Dulce Basin (region A) and a zone at lower latitudes (region B). The LMDZ selected regions represent the geographical area of the Sali-Dulce Basin (box A), and two areas outside of the basin at lower latitudes (boxes B and C). A statistical downscaling method is used to connect the large-scale climate variables inferred from LMDZ and the reanalyses, with the hydrological Soil Water Assessment Tool (SWAT) model in order to simulate the Rio Sali-Dulce discharge during 1950-2005. The SWAT simulations are then used to force the water balance of Laguna Mar Chiquita, which experienced an abrupt level rise in the 1970's attributed to the increase in Rio Sali-Dulce discharge. Despite that the lowstand in the 1970's is not well reproduced in either simulation, the key hydrological cycles in the lake level are accurately captured. Even though satisfying results are obtained with the SWAT simulations using downscaled reanalyses, the lake level are more realistically simulated with the SWAT simulations using downscaled LMDZ data in boxes B and C, showing a strong climate influence from the tropics on lake level fluctuations. Our results highlight the ability of downscaled climatic data to reproduce regional climate features. Laguna Mar Chiquita can therefore be considered as an integrator of large-scale climate changes since the forcing scenarios giving best results are those relying on global climate simulations forced with observed sea surface temperature. This climate-basin-lake model is a promising approach for understanding and simulating long-term lake level variations

EUROMED Patrimoines Partagés : Réalisations et Calendrier 1 du Projet

Poster scientifique pour le Programme EUROMED Patrimoines Partagés(CEE/CITERES-EMAM et 15 partenaires étrangers

EUROMED Patrimoines partagés : Réalisations et Calendrier 2 du Projet

Poster scientifique pour le Programme EUROMED Patrimoines Partagés(CEE/CITERES-EMAM et 15 partenaires étrangers

EUROMED Patrimoines Partagés : Conclusions et Perspectives du Projet

Poster pour le Programme EUROMED Patrimoines Partagés(CEE/CITERES-EMAM et 15 partenaires étrangers

EUROMED Patrimoines Partagés : Objectifs du Projet

Poster scientifique pour le Programme EUROMED Patrimoines Partagés(CEE/CITERES-EMAM et 15 partenaires étrangers

Synthèse énantiosélective de nouveaux composés spirohétérocycliques

Communication oral

EUROMED Patrimoines Partagés : Présentation des Partenaires du Projet

Programme EUROMED Patrimoines Partagés(CEE/CITERES-EMAM et 15 partenaires étrangers

Hydrological modelling of a closed lake (Laguna Mar Chiquita, Argentina) in the context of 20th century climatic changes

A major hydroclimatic change occured in southeastern South America at the beginning of the 1970s. This change was recorded in Laguna Mar Chiquita (central Argentina), the terminal saline lake of a 127,000 km(2) catchment as a dramatic rise in lake level larger than any observed over the past 230 years. Based on available continuous lake level monitoring since 1967, our study aimed to develop a lake water balance model for investigating the link between climate and lake level variations. Since un-gauged downstream surfaces represented approximately 80% of the catchment, the main challenge of the model development and implementation came from estimating the magnitude of catchment inputs from sparsely available gauge data. We determined a strongly negative water balance in the un-gauged part of the catchment that can be attributed to evapotranspiration in two large surface water hydrosystems. The chloride balance indicated that the lake is hydrologically closed, without significant groundwater outflows. Using contrasted hydroclimatic conditions, the robustness of the model calibration was evaluated with the model residual, and a short validation proposed for the 1998-2006 time period. Sensitivity analyses were performed in order to identify the main forcing factors of lake variations. We determined that the abrupt lake level rise in the early 1970s could be attributed to increased runoff in the upper northern sub-basin, suggesting a tropical climatic influence. Based on available hydroclimatic data, we propose a continuous lake level simulation for the 1926-2006 time period which could be used as a reference curve for better constraining paleohydrological reconstructions from sedimentary proxies