PO RIVER PRODELTA: AN ARCHIVE OF THE HUMAN IMPACT

Biside natural factors, the growth patterns of modern deltas reflect increasing human impacts affecting both catments or directly the delta regions. To fully appreciate the natural behaviour of shallow water depositional systems before and under major human impacts, it is necessary to extrapolate time-averaged estimates of changes in sediment suplply from indirect data, such as the volume of depositional units (delta lobes) for which the thickness distribution can be measured from HR seismic profiles. The depositional impacts (thicness, distribution) of flood events in prodelta systems, define ways to extrapolate this knowledge to older flood events at century scales. Using the Fall-2000 flood of the Po river as an example, we demostrate that it is possible to use the associations of benthic foraminifera, thecamoebians, concentrations (X, ARM, SIRM,) and grain size (SIRM/ARM, SIRM X, ARM/X) related magnetic parameters, in prodelta environment. All together these parameters allow to reconstruct the impact of recent and ancient flood events even where sedimentary structures are not unequivocal. An icreasing contribution of magnetic minerals with larger grain-size is correlate with minima in flocculation observed in the sediment.