Field investigation of rill and ephemeral gully erosion in the Sparacia experimental area, South Italy

This paper reports the results of a field investigation aiming at characterizing the morphology and hydraulics of both rills and ephemeral gullies (EGs) monitored at Sparacia experimental area, Sicily, Italy. The comparison between rill and interrill erosion measurements showed that sediment delivery processes occurred in some erosive events and that the rill erosion rate was dominant in many cases.The measurements were used for testing both the empirical relationships between the channel (rill, EGs and gully) length and its eroded volume and among the morphological variables (length, width, depth and volume) describing the channelized process.Finally, the rill and EGs hydraulic geometry was modelled by three well known power equations relating the discharge with the mean flow velocity, with the flow depth and with the width of each channel segment, respectively. The rill measurements also showed that the flow velocity was affected by the rill segment slope while the flow depth and width were controlled by the plot slope. Therefore, three equations, taking into account these slope effects, were proposed to estimate the hydraulic characteristics of the rills monitored at the Sparacia area.

► Rill and ephemeral gully erosion in Sicily, Italy.
► At event scale rill erosion is dominant in comparison with interrill erosion.
► The severity of the channelized erosion process can be estimated by channel length.
► A morphological similarity between rills and ephemeral gullies exists.
► Plot slope affects rill width and depth.