Document Type : Research Paper
Authors
1 Department of Watershed Management, Faculty of Natural Resources, Tarbiat Modares University, Noor, Iran.
2 Department of Watershed Management, Faculty of Natural Resources, Tarbiat Modares University
3 Department of Physics, Faculty of Sciences, University of Isfahan, Isfahan, Iran
Abstract
Introduction:
Estimating soil erosion and sedimentation using radioactive elements is a tool used to provide erosion/deposition maps and calculate sediment budget components. This study aimed to compare the sediment budget components over the periods of 100-120 years and the last 60 years, respectively, using 210Pbex and 137Cs radionuclides in the control sub-watershed of the Khamsan representative-paired watershed.
Materials and methods:
Soil sampling in the control sub-watershed was conducted using a systematic-random approach at 57 points, appropriately distributed across different land uses. To calculate the erosion/deposition intensity at each point, the diffusion and migration model and mass balance model II were used for non-agricultural lands agricultural lands, respectively. Erosion/stable/deposition area maps were created by comparing the inventories of 210Pbex and 137Cs with reference areas. Finally, the average erosion/deposition intensity distribution map was prepared using the working unit approach, and the components of the sediment budget were calculated as the average of the last 100-120 years using 210Pbex and the average of the last 60 years using 137Cs.
Results and discussion:
The comparison of sediment budget results in the studied sub-watershed showed that in the last 100-120 year and the last 60 years, the average total soil erosion was 292.87 and 526.87 (ton year-1), respectively. The average total deposition was 7.07 and 20.26 (ton year-1), and the average net soil erosion (sediment yield) was 285.79 and 506.61 (ton year-1), respectively. In the two time periods of 100-120 years and the last 60 years, the average erosion intensity was estimated at 2.92- and 5.25-ton ha-1 year-1, and the sediment yield was 2.85- and 5.05-ton ha-1 year-1, respectively.
Keywords
)