Present versus long term sediment yield to the Adriatic Sea and the reliability of gauging stations data

Carlo Bartolini(*) & Katia Fontanelli
(*) Corresponding author: C. Bartolini, Dipartimento di Scienze della Terra, Università di Firenze, Via G. La Pira, 4 - 50121 Firenze (Italy). Tel. 055-2757522; Fax. 055-218628; e-mail: bartolini@unifi.it.

The current denudation rate over an 128 000 km2 catchment area, encompassing the southern watershed of the Alps, the eastern watershed of the Northern Apennine and part of the Dinarides, was evaluated by means of a wide-reaching appraisal of the suspended load discharge of rivers now feeding the Northern Adriatic Sea. Data from gauging stations located on Alpine and Northern Apenninic rivers were matched to data derived from reservoirs silting and delta growths in lacustrine basins. The area weighed denudation rate obtained from suspension and solution load measurements in the southern watershed of the Alps is 0,071 mm/a while for the Northern Apennine it amounts to 0,431 mm/a. Reservoir silting surveys indicate values of respectively 0,151 and 0,771 mm/a, which also include the bed load component of river sediment yield. The difference is however also due to traditional point sampling techniques frequently underrating the suspended yield of rivers. The Alpine values are consistent with those reported by HINDERER (1999, 2001) which are based on different data sets. The present denudation rates are then compared with literature data on long term average denudation rates (post LGM, Quaternary, Pliocene). The present-day impact of man as a geological agent is not clearly evidenced by modern rates when compared to long term ones, since the manifold indirect and direct anthropic influences largely balance each other.

Denudation rate, Northern Apennine, Alps, Dinarides.