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| Response of soil erosion to watershed revegetation: role of sediment connectivity and erosion power |
| Received:February 13, 2023 |
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| KeyWord:soil erosion;sediment connectivity;runoff erosion power;vegetation restoration;nested watershed |
| Author Name | Affiliation | E-mail | | GUO Zongjun | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China
College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China | | | WU Lei | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, China
College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China | lwu@nwsuaf.edu.cn | | ZHANG Huiyong | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China
College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China | | | LIU Shuai | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A&F University, Yangling 712100, China
College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China | |
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| Abstract: |
| To identify the changing processes of erosion in revegetated watersheds, a model-based methodology was developed to simulate erosion processes and assess the spatial and temporal patterns of erosion and revegetation in the Yanhe watershed. The methodology combined the Revised Universal Soil Loss Equation(RULE), Index of Connectivity(IC), and Soil and Water Assessment Tool(SWAT)to model the variability in runoff erosion processes and the characteristics of the response to vegetation restoration. The results show that:damage due to erosion in the Yanhe watershed has generally improved:the average erosion rate had exceeded 80 t·hm-2·a-1 in most years between 1985 and 2000 and decreased to approximately 10-30 t · hm-2 · a-1 around 2015. The change in the soil erosion rate can be attributed to the degree of vegetation restoration, as evidenced by both measures showing a negative correlated interannual trend. The runoff erosion power decreased over time, from 13.28×10-4 to 4.40×10-4 m4·s-1·km-2 from 1985 to 2020, and a strong scale effect was observed:runoff erosion increased very quickly as a power function of the decreasing area, when the watershed area was less than 1 000 km2. The IC results showed spatial variability, with small IC values in slope areas and large values in gullies. IC ranged from -13.11 to 1.95 across the watershed, being smaller in the middle reaches and larger in the upper and lower reaches, and decreased as the nested catchment area increases. IC was highly correlated with Normalized Difference Vegetation Index(NDVI)at the time scale(R2=0.98), and there was a gradual decrease in IC with increasing vegetation cover, suggesting that increasing vegetation impedes the degree of connectivity of sediment pathways. Meanwhile, IC and erosion were strongly correlated over time, indicating that areas with high IC have higher erosion risk and should be the focus of further erosion control. In general, the methodological framework demonstrated in this study has explanatory power and provides a new way to explore the erosion patterns in the watershed. |
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