Suspended Sediment Transport in Mediterranean Streams: Monitoring and Load Estimation

The suspended sediment (SS) load provides valuable insights into soil loss magnitude,requiring comprehensive monitoring of streamflow (Q) and SS concentrations (SSC) across varioushydrological conditions. The primary aim of this paper was to quantify SS loads in two mountainousriver basins: the Carapelle (506 km2) and the Celone (72 km2) located in Apulia (Southeast Italy) wheredifferent monitoring strategies were adopted (i.e., continuous and discrete). The specific objectivewas to develop sediment rating curves to address gaps in the SSC time series. An optical probewas used to continuously monitor the SSC during 2007 to 2011 in a river section of the Carapelleriver, while Q was measured with the ultrasonic method. A comprehensive dataset comprisingcontinuous Q measurements and discrete SSC measurements was systematically acquired for theCelone river over the period of 2010 to 2011. Distinct sediment rating curves were formulated forthree specific subsets of data delineated by discernible hydrological conditions (i.e., high, normal,and low flow) and SSCs were computed for the missing daily records. The annual specific sedimentload exhibited a range of 2.4 to 6.06 t ha?1 yr?1 for the Celone river, while the Carapelle riverdisplayed a range of 0.9 to 7.45 t ha?1 yr?1. A significant majority of the SS load was transportedduring high-flow conditions, accounting for over 80% of the total load. In contrast, during low-flowconditions, the SS load constituted less than 1% of the total load. The findings of this study highlightthe significance of the hydrological regime as a critical factor influencing sediment transport inmountainous Mediterranean rivers. Furthermore, it demonstrates that the duration of the samplingperiod, along with its specific characteristics, such as dry or wet conditions, can have a substantialimpact on the accurate quantification of the sediment load.