chapter - Atmospheric and Oceanic Science

6.1. General considerations
Climate trends discussed in chapter 5 transform in even more pronounced
hydrological trends. This implies that the hydrological regime cannot longer be
consider stationary Data and cases that illustrate this situation are presented and
analyzed in this chapter that was particularly noticeable in the last decades of the
twentieth century.
6.2. River streamflows
Hydrological trends
In figure 6.1 are shown the annual maximum, minimum and mean daily flows
of the Paraná River in the section Paraná-Santa Fe for a period little longer than one
century, namely 1902-2004 (for the last year are only available data until August at
the moment of this writing), based on the data provided by Sistema de Información
y Alerta Hidrológico del INA-Argentina (System of Information and Hydrological
Alert of the INA-Argentina). The figure suggests that the 1970 decade constitutes
a transition stage between two different states of relative statistical stability: one in
the period 1902-1970 that will be denominated "old stage” and another one, the second,
during the 1980 and 1990 decades (1980-2000) that will be called "modern
stage". Additionally, it can be distinguished a behaviour a bit different in the first
years of the present century that will be named "current situation" since it still cannot
be assigned any statistical relevance.
Fig. 6.1. Annual maximums, minimums and mean of the daily flows of the Paraná River in the section
Paraná-Santa Fe for period 1902-2004.
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