A review of radiometric analysis on soil erosion and deposition studies in Africa

Soil erosion is one of the main soil degradation phenomena that threaten sustainable use of soil productivity thus affecting food security. In addition, it leads to reservoir storage capacity loss because of sedimentation. This not only affects water quantity but also water quality. Worldwide, annual loss in reservoir storage capacity due to sedimentation is 0.5 to 1%. Similarly, about 27% of land in Africa is largely degraded by erosion. As a result, there is need to minimize soil erosion and deposition through site specific estimation of soil erosion and deposition rates in the reservoirs. To achieve this, Fallout RadioNuclides (FRNs) are some of the methods in use. The most common radionuclides include; ¹³⁷Cs, ²¹⁰Pb and ⁷Be. Only few countries in Africa have exploited these FRNs. In these countries, ¹³⁷Cs has been largely exploited but in some regions, it has been reported to be below minimum detection limit. Using ¹³⁷Cs and ²¹⁰Pb, maximum reference inventory in Africa is found to be 1450 and 2602 Bq/m², respectively. However, there is minimal application of ⁷Be within the continent. Also, very little has been done in Africa to assess chronology and sedimentation rates of reservoirs using FRNs measured from sediment cores. In conclusion, a gap still exists on FRNs application in Africa in assessing soil erosion, deposition and reservoir sedimentation.