  We have used the Kolmogorov complexities, sample and permutation entropies to
quantify the randomness degree in river flow time series of two mountain rivers
in Bosnia and Herzegovina, representing the turbulent environmental fluid, for
the period 1926-1990. In particular, we have examined the monthly river flow
time series from two rivers (Miljacka and Bosnia) in mountain part of their
flow and then calculated the Kolmogorov Complexity (KL) based on the Lempel-Ziv
Algorithm (LZA) (Lower - KLL and Upper - KLU), Sample Entropy (SE) and
Permutation Entropy (PE) values for each time series. The results indicate that
the KLL, KLU, SE and PE values in two rivers are close to each other regardless
of the amplitude differences in their monthly flow rates. We have illustrated
the changes in mountain river flow complexity by experiments using (i) the data
set for the Bosnia River and (ii) anticipated human activities and projected
climate changes. We have explored the sensitivity of considered measures in
dependence on the length of time series. In addition, we have divided the
period 1926-1990 into three sub-intervals: (a) 1926-1945, (b)1946-1965 and
(c)1966-1990, and calculated the KLL, KLU, SE and PE values for the various
time series in these sub-intervals. It is found that during the period
1946-1965, there is a decrease in their complexities, and corresponding changes
in the SE and PE, in comparison to the period 1926-1990. This complexity loss
may be primarily attributed to (i) human interventions, after Second World War,
on these rivers because of their use for water consumption and (ii) climate
change in recent time.
