Quantifying erosion using 137Cs and 210Pb in cultivated soils in three Mediterranean watershed: Synthesis study from El Hachef, Raouz and Nakhla (North West Morocco)

Measurements of soil erosion on the Moroccan landscape using classical erosion methods have been the objective of several research studies, but these classical methods are difficult to conduct, time consuming and very expensive and the quantitative estimation of soil loss remains insufficient particularly in the North of Morocco. In this study, we present results on soil erosion quantification using Cs-137 and Pb-210 in three dam catchments: El Hachef, Raouz and Nakhla. In each area inventories of Cs-137 and Pb-210(ex) were measured in cultivated soils and compared to reference inventories (noneroded) measured in the same area. The differences were converted onto erosion or accumulation rate using mass balance models (MB1 and MB2). In El Hachef, the mean erosion rates using Cs-137 with MB1 and MB2 models and Pb-210(ex) with MB2 model are respectively 32 t ha(-1) yr(-1), 29 t ha(-1) yr(-1) and 20 t ha(-1) yr(-1). In Raouz, the mean erosion rates using Cs-137 with MB1 and MB2 models and Pb-210(ex) with MB2 model are respectively 13.9 t ha(-1) yr(-1), 12.2 t ha(-1) yr(-1) and 16.1 t ha(-1) yr(-1). In Nakhla, the mean erosion rates using Cs-137 with MB1 and MB2 models and Pb-210(ex) with MB2 model are respectively 33.1 t ha(-1) yr(-1), 41.3 t ha(-1) yr(-1) and 20 t ha(-1) yr(-1). These results show the severity of erosion in North West Morocco compare to other Mediterranean countries and the necessity to seek for urgent solutions to stem this problem. (C) 2012 Elsevier Ltd. All rights reserved.