Fig. 2.

Hydroclimatic fluctuations produce flow regime instability. (A) Hydroclimatic fluctuations in the Piave River at Cancia, Italy, during the summer, identified by the underlying fluctuations of λ, α, and k across consecutive, disjointed groups of 2 y (representing the variability of the number, magnitude, and response time of flow-producing rainfall events). (B) Experimental evidence of the effect of hydroclimatic fluctuations on the streamflow distribution: The frequency changes are particularly evident for the range of flows, , that had not been observed during 1998–1999 but became relatively frequent during 2000–2001. (C) Relative magnitude of the long-term variability of hydroclimatic parameters λ, α, and k (including the shape and rate parameters of the flow pdf: and ) increases with the seasonal .