Natural streamflow regime alterations: Damming of the Piave river basin (Italy)

摘要

A novel approach is proposed to estimate the natural streamflow regime of a riverand to assess the extent of the alterations induced by dam operation related toanthropogenic (e.g., agricultural, hydropower) water uses in engineered river basins. Themethod consists in the comparison between the seasonal probability density function(pdf) of observed streamflows and the purportedly natural streamflow pdf obtained by arecently proposed and validated probabilistic model. The model employs a minimum oflandscape and climate parameters and unequivocally separates the effects ofanthropogenic regulations from those produced by hydroclimatic fluctuations. Theapproach is applied to evaluate the extent of the alterations of intra‐annual streamflowvariability in a highly engineered alpine catchment of north‐eastern Italy, the Piave river.Streamflows observed downstream of the regulation devices in the Piave catchment arefound to exhibit smaller means/modes, larger coefficients of variation, and morepronounced peaks than the flows that would be observed in the absence of anthropogenicregulation, suggesting that the anthropogenic disturbance leads to remarkable reductions ofriver flows, with an increase of the streamflow variability and of the frequency ofpreferential states far from the mean. Some structural limitations of managementapproaches based on minimum streamflow requirements (widely used to guide waterpolicies) as opposed to criteria based on whole distributions are also discussed.