Types and volumes of in-channel wood in three Italian gravel-bed rivers suffering from different degrees of human disturbances

The evaluation of the various degree of influence of in-channel large wood is receiving an increasing interest from various disciplines (biology, ecology, geomorphology and hydraulic engineering), because of its both positive and potentially negative effects. This study analyses the physical characteristics, quantity and morphological effects of in-channel wood on three gravel-bed rivers located in north-eastern Italy (Brenta, Piave, and Tagliamento), which are characterized by different ranges of human disturbances. It has been verified that the Tagliamento River (the less impacted of the three study rivers) features the higher spatial density and volumes of single logs and wood jams than the Piave and Brenta. The same transition from the lesser to the higher disturbed river is respected if the volumes of sediments deposited (below) and scoured (around) jams are considered.