Background The Loess Plateau in China is one of the regions with the most severe soil erosion in the world. Terraced fields, as an important soil and water conservation engineering measures, play an important role in soil erosion prevention and control. However, under the background of climate change and frequent extreme rainstorm, terrace collapse and damage often occur, its stability evaluation has become an urgent research issue.
Methods We used high-resolution image data obtained from drones, extract terrain indicators before and after the construction of terraced fields in various areas, and visual interpretation methods to extract terraced field blocks in the sample areas, which was based on the relationship between field width, terraced wall height, and ground slope. The stability of terraced fields was studied in the typical sample areas of Liudaogou and Chabagou watersheds in the loess hilly and gully region.
Results 1) After the construction of terraced fields, the slope gradient, slope length, and LS factor of the land surface showed a decreasing trend compared to that before the construction. The slope of terraced wall showed an increasing trend, while the slope length and LS factor generally showed a decreasing trend. 2) Based on the relationship between field width and slope gradient, the stable area, stable but inconvenient to cultivate area, and unstable area in the Liudaogou sample area accounted for 37.86%, 0.09%, and 62.05% respectively, while those in the Chabagou sample area accounted for 68.58%, 0.6%, and 30.81%, respectively. 3) Based on the relationship between the height and slope gradient of the terraced wall, the stable area, stable but inconvenient-to-cultivate area, and unstable area of the Liudaogou sample area each accounted for 36.07%, 1.06%, and 62.67%, while the Chabagou sample area accounted for 4.32%, 4.22%, and 91.46%, respectively.
Conclusions The construction of terraced fields may improve the original slope terrain characteristics and be beneficial for soil erosion control. When the original slope is small, the width of the field can be wider, and the terraced wall height should not be too low. When the original slope is relatively steep, the terraced wall should not be too high, which may cause collapse. This result may provide a basis for optimizing the design and maintenance of terraced fields.
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