Using caesium-137 and unsupported lead-210 measurements to explore the relationship between sediment mobilisation, sediment delivery and sediment yield for a Calabrian catchment
Paolo Porto A B D , Des E. Walling A , Giovanni Callegari C and Antonina Capra BA Department of Geography, University of Exeter, United Kingdom.
B Dipartimento di Scienze e Tecnologie Agro-Forestali e Ambientali, Università degli Studi ‘Mediterranea’ di Reggio Calabria, Italy.
C C.N.R. – Istituto per i Sistemi Agricoli e Forestali del Mediterraneo, Sezione Ecologia e Idrologia Forestale, Rende (Cs), Italy.
D Corresponding author. Email: p.porto@exeter.ac.uk
Marine and Freshwater Research 60(7) 680-689 https://doi.org/10.1071/MF08050
Submitted: 25 February 2008 Accepted: 25 February 2009 Published: 28 July 2009
Abstract
Recent concern about the many environmental problems associated with the transport of fine sediment by rivers has generated a need to obtain spatially distributed evidence of the erosion rates operating within a catchment and to explore more explicitly the links between sediment mobilisation, transfer, storage and output. In the past few decades, the fallout radionuclides caesium-137 (137Cs) and unsupported lead-210 (210Pbex) have been successfully used as tracers to estimate soil erosion and deposition rates in many areas of the world. However, to date, most studies using this approach have focussed on relatively small areas, such as individual fields or small catchments. There is a need to explore the potential for upscaling the approach to larger areas or catchments. The present paper reports an attempt to use the fallout radionuclides 137Cs and 210Pbex to explore further the relationship between sediment mobilisation, sediment transfer and storage, and sediment yield for a medium-scale (31.61 km2) catchment located in Calabria, southern Italy. The results emphasise that the low value of specific sediment yield derived for the study catchment from measurements of the suspended sediment flux at the catchment outlet obscure the existence of appreciable erosion rates in many areas of the catchment. Much of this erosion is balanced by deposition and sediment storage, resulting in a relatively low sediment delivery ratio for the catchment.
Additional keywords: sediment load, soil erosion.
Acknowledgements
The study reported in this paper was supported by grants from MIUR RdB 2006 and IAEA (Technical Contract 15478) and by the provision of facilities for gamma spectrometry measurements by the Department of Geography at the University of Exeter, UK. The assistance of Helen Jones and Sue Rouillard in producing the figures and of Jim Grapes in undertaking the gamma spectrometry measurements are gratefully acknowledged. Thanks are also extended to both the referees and the Guest Editor for their useful comments.
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