Human impact on sediment yield and channel dynamics in the Arno River (Central Italy)

The Arno River basin has been subjected to human disturbance and modification since Roman times. Until 1800 the main aims of such modifications were to provide flood protection for adjacent towns and to acquire new land for cultivation. The combination of reduced sediment supply and increased sediment transport capacity resulted in extensive streamed degradation that threatened the stability of several bridges and other structures. The relative importance of human activity in causing channel adjustment compared with natural changes, such as the progressively lower runoff recorded during the last seven decades, is discussed.