Suspended sediment flux monitoring in an intra-Apennine poorly gauged basin

In small river basins, road building activities, if not properly carried out, can cause a significant increase in suspended sediment fluxes. In this study the effect of construction activity and its influence on suspended solid loads in an intra-Apennine forested small catchment, draining into Bilancino reservoir (Florence, Italy) was studied. Special attention was drawn to sedimentation processes in the drainage network near logging sites. This research links sediment sources and fluxes using a direct monitoring approach. The procedures take into account different portions the upstream source areas to assess the drainage network connectivity. Monitoring program was conducting by using time integrated sediment traps located along two stream inlets of the Bilancino reservoir. This study area was chosen because of (i) the lack of investigations on sediment loads, and (ii) to evaluate the impact of a new road construction. The results show that the highway construction has caused an 8-fold increase in suspended sediment load relative to a watershed only affected by natural landslides and agricultural activities. The results show that for first and second order basin with a flow velocity of about 1 m s–1 the time integrated sediment traps are appropriate tools for monitoring poorly gauged stream.