5. Conclusion
The SegNet model was used to recognize ephemeral gullies and extract their morphological features at a watershed scale from 2009 to 2021 to analyze temporal and spatial distribution characteristics of ephemeral gullies in the hilly and gully region of the Loess Plateau. This study showed that ephemeral gullies are mainly located in the southern part of the watershed, where there are complex landforms and steep slopes. The increase in ephemeral gully number, length, width, total area, frequency, density, dissection degree, and erosion volume was 97 y–1, 1.66 m y–1, 0.04 m y–1, 4,213.39 m2y–1, 2.87 km2y–1, 0.12 km km–2y–1, 0.0125% y–1, and 22.12 m3 km–2 y–1, respectively. The regression analysis revealed a power function relationship between ephemeral gully erosion volume and length:\(V=0.0842L^{1.1932}\ (R^{2}=0.80,\ n=1,594)\). Indeed, The regression analysis revealed ephemeral gully length can be measured accurately and easily from high-resolution satellite images. This study demonstrated that assessing ephemeral gully erosion volume and volume rate is feasible using a regression model of ephemeral gully erosion volume and length from historical high-resolution remote sensing images in the hilly and gully region of the Loess Plateau in China.