IANIGLA   20881
INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Precipitation and river discharge in the subtropics
Autor/es:
FERRERO, M.E.; VILLALBA, R.; DE MEMBIELA, M.
Lugar:
Tilcara, Jujuy
Reunión:
Workshop; IAI CRN 2047, Final Science Meeting; 2011
Resumen:
The disruption of the northeasterly humid-air flow by the Sub-Andean
mountain ranges generates a latitudinal-band of enhanced orographic
precipitation in subtropical northwestern Argentina (SNWA). These Sub-Andean mountain
areas are the major sources of water for the river systems in NWA. It has been
shown that tree-ring variations from the montane forests in SNWA are sensitive
to annual or even seasonal variations in precipitation. Consequently, they
provide a unique opportunity to evaluate the long-term variability in
precipitation and streamflow across the region. Principal component analysis
was applied to a network of Juglans
australis chronologies in SNWA to determine the common patterns of variance
among records. Correlation and multiple regression techniques were used to
determine the relationships between the tree-ring dominant patterns and monthly
rainfall variations. Transfer functions were developed between precipitation
and tree growth to estimate past variations in precipitation during the past
2-3 centuries using tree-ring records as predictors. Our results indicate that
variations in growth are related to late spring-summer rainfalls, the season of
the year recording the largest precipitation, and consequently, the maximum
runoffs in SNWA. According to our reconstructions, precipitation variability
has increased since early 1990s leading to years of extremely-wet followed by
very-dry events. Reconstructions of seasonal precipitation and streamflow of
different rivers may provide an important framework to evaluate the current
hydroclimatic changes in the subtropical regions in South America influenced by
the summer monsoon system.