Flux and fate of river-discharged sediments to the Adriatic Sea

Small rivers, particularly those draining mountainous terrain, discharge disproportionately large quantities of sediment to the global ocean. Because small mountainous rivers are more susceptible to catastrophic events, they tend to discharge their sediments over relatively short periods of time, such as during floods. The impact of small mountainous rivers is especially evident on the coastal ocean, such as the Adriatic Sea where fully 75% of the estimated 145 million tons (Mt) of discharged sediment comes from rivers with basin areas smaller than 7000 km(2). Within this semi-enclosed basin in the northeast of the Mediterranean Sea, of particular note are the high sediment loads of five Albanian rivers (located in the southeast), which, prior to dam construction, collectively discharged about 85 Mt yr(-1) perhaps much of it at hyperpycnal concentrations, which would have allowed the sediment to bypass the shelf and be deposited at greater depths. Geochemical data confirm that Albanian river sediment extends well into the southern and central Adriatic Sea. Delineating and understanding the flux and fate of Adriatic Sea sediments may be best facilitated through the reanalysis of existing river datasets and the acquisition of new river data, particularly during periodic floods, high-resolution seismic profiling coupled with site-pecific coring, as well as application of integrated ocean-sediment numerical models.