  This paper explores a large collection of about 377,000 observations,
spanning more than 20 years with a frequency of 30 minutes, of the streamflow
of the Paglia river, in central Italy. We analyze the long-term persistence
properties of the series by computing the Hurst exponent, not only in its
original form but also under an evolutionary point of view by analyzing the
Hurst exponents over a rolling windows basis. The methodological tool adopted
for the persistence is the detrended fluctuation analysis (DFA), which is
classically known as suitable for our purpose. As an ancillary exploration, we
implement a control on the data validity by assessing if the data exhibit the
regularity stated by Benford's law. Results are interesting under different
viewpoints. First, we show that the Paglia river streamflow exhibits
periodicities which broadly suggest the existence of some common behaviour with
El Nino and the North Atlantic Oscillations: this specifically points to a (not
necessarily direct) effect of these oceanic phenomena on the hydrogeological
equilibria of very far geographical zones: however, such an hypothesis needs
further analyses to be validated. Second, the series of streamflows shows an
antipersistent behaviour. Third, data are not consistent with Benford's law:
this suggests that the measurement criteria should be opportunely revised.
Fourth, the streamflow distribution is well approximated by a discrete
generalized Beta distribution: this is well in accordance with the measured
streamflows being the outcome of a complex system.
