A regional statistical analysis of unimpaired low river flows and implication for environmental minimum flow requirements

Low flow regime is tightly dependent on catchment hydrogeological features and a detailed surface and groundwater catchment analysis is necessary for an accurate characterization. However on a practical perspective regional statistical analysis is widely applied to derive indexes to characterize low flow regimes in poorly gauged watersheds. In this study we focus on some of the well known low flow statistics such as the Q7,T and the flow duration curve and we particularly investigate the importance of geological features. It has been found that it is possible to derive regional flow-duration and flow-frequency curves starting from the knowledge of a BFI regional value, which is essentially dependent on permeability