Validating the Use of ¹³⁷Cs Measurements to Derive the Slope Component of the Sediment Budget of a Small Rangeland Catchment in Southern Italy

Abstract

The sediment budget is a key concept and tool for characterizing the mobilization, transfer and storage of fine sediment within a catchment. Caesium-137 measurements can provide valuable information on gross and net erosion rates associated with sheet and rill erosion that can be used to establish the slope component of a catchment sediment budget. However, there is a need to validate the use of 137 Cs measurements for this purpose, because their reliability has sometimes been questioned. The study reported focuses on a small (3·04 ha) steepland (mean slope 37%) catchment in Southern Italy. It exploits the availability of information on the medium-term sediment output from the catchment provided by the construction of a reservoir at its outlet in 1978 and the existence of estimates of soil redistribution rates derived from 137 Cs measurements made on 68 replicate soil cores collected from the slopes of a substantial proportion of the catchment in 2001, to validate the use of 137 Cs measurements to construct the slope component of the catchment sediment budget. An additional 50 replicate soil cores were collected from the catchment slopes for 137 Cs analysis, to complement the data already available. Nine cores collected from the area occupied by the reservoir were used to estimate the mean annual sediment input to the reservoir. In the absence of evidence that the poorly developed channel system in the catchment was either a significant sediment source or sink, it was possible to directly compare the estimate of net soil loss from the catchment slopes (7·33 Mg ha À1 y À1 ) with the estimate of sediment output from the catchment provided by the reservoir deposits (7·52 Mg ha À1 y À1 ). Taking account of the uncertainties involved, the close agreement of the two values is seen as providing a convincing validation of the use of 137 Cs measurements to both estimate soil redistribution rates and as a basis for constructing the slope component of the sediment budget of a small catchment.

Wildfire Effects on Suspended Sediment Delivery Quantified Using Fallout Radionuclide Tracers in a Mediterranean Catchment

“…In this sense, caesium‐137 ( 137 Cs) and excess lead‐210 ( 210 Pb ex ) have been widely applied as tracers to determine the relative hillslope surface and channel bank source contributions to the sediment that is either stored and/or transported through the river networks (Walling ; Porto et al . ). Their use within wildfire studies is relatively limited, and work‐to‐date has been almost exclusively based within Australia (Wallbrink et al .…”

Coarse and fine sediment sources in nested watersheds with eucalyptus forest

“…Physico‐chemical properties of eroded sediment have close relationship with soil and sediments from different sources within a watershed. Each sediment source has different characteristics in magnitude of contribution and potential contamination, whereas identifying sediment sources is critical in understanding sediment emission rate and in management of sediments eroded at the watershed scale (Minella et al, ) and for designing soil and water conservation practices (Porto, Walling, La Spada, & Callegari, ). Thus, using natural tracers by means of geochemical composition analysis of soil and sediment in statistical methods with fingerprinting technique allows quantifying the main sources contributions to the global sediment (D'Haen, Verstraeten, & Degryse, ).…”

Influence of climate and land use changes on recent trends of soil erosion rates within the Russian Plain

“…The additional field data covering more than 20–25‐year intervals should be collected for the more detail assessment of the contemporary trend of the soil erosion rates in the different landscape zones of the Russian Plain. Application of bomb‐ and Chernobyl‐derived 137 Cs for evaluation of sedimentation rates in the sediment sinks catching deposits delivered from adjacent cultivated land is the promising tool for evaluation of erosion rate trend for two time slices (Golosov et al, ; Golosov et al, ; Porto, Walling, La Spada, & Callegari, ).…”