Deterministic chaotic dynamics of Raba River flow (Polish Carpathian Mountains)

•Initial clues from preliminary analysis of the observed system.•Discrimination between determinism and randomness made by three diverse techniques.•Distinction between non-chaotic and chaotic motion achieved by two independent tests.•Fractal analysis revealed dissipative, deterministic chaotic dynamics.•Nonlinearity and stationarity tests complemented the research.

SummaryIs the underlying dynamics of river flow random or deterministic? If it is deterministic, is it deterministic chaotic? This issue is still controversial. The application of several independent methods, techniques and tools for studying daily river flow data gives consistent, reliable and clear-cut results to the question. The outcomes point out that the investigated discharge dynamics is not random but deterministic. Moreover, the results completely confirm the nonlinear deterministic chaotic nature of the studied process. The research was conducted on daily discharge from two selected gauging stations of the mountain river in southern Poland, the Raba River.