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This study aims to evaluate changes in soil erosion and sedimentation processes in the Northwest region of Morocco based on the use of fallout radionuclide techniques. The Caesium-137 technique was combined with the re-sampling approach to assess soil erosion rates associated with two periods (1954–2000/2001 and 1954–2017/2018) in four agricultural fields located in El Hachef and Raouz watersheds, and excess Lead-210 was used to estimate the temporal variation of the sedimentation rate in a water reservoir named "9th of April 1947", located in this region, downstream from El Hachef watershed. The results show that the net soil erosion rates had decreased in the two study fields of El Hachef watershed, from 26.3 to 20.2 t ha−1 year−1 and from 50.8 to 42.7 t ha−1 year−1, respectively, and in one field of Raouz watershed, from 19.4 to 16.1 t ha−1 year−1, due to some beneficial changes in land use consisting of more frequent fallow periods combined with natural vegetation and crop rotation practice. However, in one of the two fields of the Raouz watershed, where agricultural practices were not changed, the net soil erosion rate increased from 4.5 to 5.7 t ha−1 year−1 between the two periods, which could be due to climate change impact on soil erosion in this area. Taking into account the relative uncertainties on the 137Cs inventories and the period elapsed between the two sampling campaigns, the results obtained by the re-sampling 137Cs method can be considered statistically significant in particular for fields with high changes in soil erosion rates. The results also indicate an increase of the sedimentation from 18.9 t ha−1 year−1 in 1950 to 79.8 t ha−1 year−1 in 2015 in the downstream water reservoir, which can be attributed to the combined impacts of both climate change and agriculture practices in the region. [ABSTRACT FROM AUTHOR]

Abstract: 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 137Cs and 210Pb in three dam catchments: El Hachef, Raouz and Nakhla. In each area inventories of 137Cs and 210Pbex 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 137Cs with MB1 and MB2 models and 210Pbex with MB2 model are respectively 32tha−1 yr−1, 29tha−1 yr−1 and 20tha−1 yr−1. In Raouz, the mean erosion rates using 137Cs with MB1 and MB2 models and 210Pbex with MB2 model are respectively 13.9tha−1 yr−1, 12.2tha−1 yr−1 and 16.1tha−1 yr−1. In Nakhla, the mean erosion rates using 137Cs with MB1 and MB2 models and 210Pbex with MB2 model are respectively 33.1tha−1 yr−1, 41.3tha−1 yr−1 and 20tha−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. [Copyright &y& Elsevier]

Water erosion poses a significant environmental threat in the Mediterranean region, with pronounced impacts observed throughout Morocco. It impairs soil quality and disrupts both sediment transport and water availability. Contributing factors range from natural (climate, topography, and geology) to anthropogenic (land use, vegetation cover, and management). This study introduces an improved Priority Actions Program/Regional Activity Centre (PAP/RAC) model, enriched with GIS and the Caesium-137 (137Cs) technique, to investigate erosion within Morocco's Raouz basin. Enhanced with additional variables including soil types, slope length, rainfall erosion potential, slope orientation, soil moisture, and land surface temperature, the model transcends the classical approach, promoting granularity and precision in predictions. In addition to the comprehensive model, the 137Cs method, which discerns long-term soil erosion and redistribution, provides a dual-faceted validation, bolstering the robustness of this project's erosion risk evaluation. This study's outcomes underscore the gravity of the erosion hazard with significant soil depletion rates ranging from 8.1 to 20 t ha−1 yr−1, demonstrating the model's alignment with empirical data, affirming its utility. The modified PAP/RAC model concurs with the 137Cs data, demonstrating its usefulness for water erosion assessment and management in similar areas. • The modified PAP/RAC model enhances erosion prediction. •Model validated with extensive 137Cs data. •GIS integration identifies erosion hotspots. •A comparative study with global erosion data. • The model adapts to diverse Mediterranean climates. [ABSTRACT FROM AUTHOR]

The Nakhla watershed was one of the most affected areas by water erosion in Northwest Morocco. This phenomenon caused the sedimentation of the Nakhla dam, an important water reservoir that contributed to water supply in the region. The motivation behind our investigation is to know the evolution of the situation in this watershed. The objective of this study is to use fallout Caesium-137 and excess Lead-210 to assess changes in soil redistribution rates during the last century and the impact of recent soil conservation practices within an agricultural field in the Nakhla watershed. The Caesium-137 technique, which has proved its efficiency in estimating erosion rates over the last 50–60 years, was associated with the re-sampling approach in the current study to reveal the response of soil redistribution rates to land use change over the last fifteen years within an upland agricultural field in Northwest Morocco under Mediterranean conditions. The excess Lead-210 was used to generate data on soil movement over a longer time window of 100 years. Subsequently, the combined use of Caesium-137 re-sampling with excess Lead-210 techniques allowed for the estimation of soil erosion rates over three periods: 1954–2002, 1954–2017 and 1917–2017. Quantification of water erosion with excess Lead-210 indicated a rate of 27 t ha−1 yr−1. Based on Caesium-137 measurements, the comparative analysis of the soil redistribution estimates over two periods (1954–2002 and 1954–2017) shows that soil loss rates have significantly decreased from 36 t ha−1 yr−1 to 29 t ha−1 yr−1 during the period between the two sampling campaigns (2002–2017) due to the beneficial impact of agricultural practices. This decrease is consistent with the available records of sediment yield in the Nakhla dam during these periods. The main findings show that the sustainable agricultural practices and the implemented soil erosion control strategy, based on more frequent fallow with natural vegetation and olive plantations, were effective in reducing soil erosion in the investigated area. • Caesium-137 technique with re-sampling approach were successfully used to study recent changes in soil erosion rates. • Lead-210 in excess allowed to assess soil redistribution rates over the last century in the study field. • Sustainable agricultural practices and suitable erosion control strategy have reduced soil erosion in the study field. • The decreasing trend in sediment yield was in agreement with the results derived from Caesium-137 measurements. • There is no observable change in soil erosion rate due to climate change impact over time. [ABSTRACT FROM AUTHOR]