Precipitation event distribution in Central Argentina : spatial and temporal patterns
Date
2015
Journal Title
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Publisher
John Wiley & Sons
Abstract
The annual amount of precipitation inputs received by a site during a full year is considered a dominant spatial and temporal
control of primary productivity and other related process in arid to subhumid ecosystems. However, to be effectively used by
plants, these inputs have to escape runoff, favoured by large and less frequent precipitation events, and evaporation losses,
favoured by small and more frequent events. Thus, available water for plant transpiration is not only influenced by the annual
sum of precipitation events but also by their frequency-size distribution. In this paper, we characterize this distribution and its
association to total annual precipitation inputs through space (five sites along a tenfold precipitation gradient across 1000 km) and
time (1961–2010) in the plains of central Argentina. We decomposed total precipitation into two structural components, which
are the frequency and mean size of events, showing that they have similar contributions (log–log slopes≈0·5) explaining
precipitation shifts in space. Over time, however, we found a preponderance of mean event size explaining precipitation
fluctuations, particularly towards wetter sites (log–log slopes increasing from 0·61 to 0·88). The relative variability of event sizes,
independent of their mean size (i.e. inequality), was numerically characterized with Gini coefficients derived from Lorenz curves,
which showed highly constant values in space and time. Assuming fixed event-size thresholds for evaporation and runoff, and
ignoring other controls beyond precipitation structure, the proportion of water potentially available for plant transpiration grew
with total precipitation, raising from 0·45 to 0·71 from the driest to the wettest sites, but displaying stronger responses to total
precipitation in time, particularly in drier sites. No long-term trends in any of the precipitation structure variables were detected.
Response functions of frequency and mean size of events to annual precipitation together with Lorenz curves appeared to be
robust descriptors of precipitation regimes that, not requiring any a priori assumptions, are useful to assess how spatial and
temporal shifts in total precipitation may concurrently affect its relative availability for plant transpiration.
Description
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Journal Article (peer-reviewed)
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Keywords
HYDROCLIMATOLOGY, PRECIPITATION, EVAPOTRANSPIRATION, AGRICULTURAL METEOROLOGY, PERIODICITY, MATHEMATICAL MODELS, CLIMATE CHANGE, WATER RESOURCES, NO-TILLAGE, TRANSPIRATION, GRASSES, WATERSHED MANAGEMENT
Citation
Magliano, P.N., Fernández, R.J., Mercau, J.L., & Jobbágy, E.G. (2015). Precipitation event distribution in Central Argentina: spatial and temporal patterns. Ecohydrology, 8, 94-104. doi:10.1002/eco.1491