An experimental station for the automatic recording of water and sediment discharge in a small alpine watershed

Rating sediment transport contributes greatly to an improved knowledge of the relationships between hydrological and sediment transport processes. In alpine watersheds the importance of these processes is not matched by a corresponding amount of available field data on sediment transport and particularly on bed load. Detailed measurements made in experimental watersheds can help collect data on sediment transport in small mountain streams. In this connection, a small watershed (5 km2) in the Italian Alps strongly affected by erosion has been equipped with an experimental station for recording water and sediment discharge data. The experimental station operates chiefly on the separation of bedload from suspended load. The two fractions are measured by different devices. The experimental equipment has been devised with different objectives: to record sediment transport data under various different hydrological conditions including flood events; to provide reliable input data for deterministic erosion models; and to test different methodologies for water sampling, water level measurement and suspended sediment concentration measurement. The station is also equipped with sensors for gathering water quality parameters, and with a device for the automatic sampling of discharge water. A detailed description of the experimental equipment and of the data recorded by the station is given.