(c) Width variation from 2012–2018 (d) Width variation from 2018–2021
Figure 6. Width spatial-temporal evolution of gullies from 2009 to 2021
3.2.4 Area and dissection degree of gullies
Table 3 shows the area distribution of gullies from 2009 to 2021. In 2009, 2012, 2018, and 2021, gully area ranged from 6.5–230.71, 4.64–246.86, 4.64–230, and 5.36–209.5 m² (average 49.12, 47.34, 46.05, and 46.36 m²), total area was 0.0566, 0.0968, 0.1111, and 0.1072 km², and dissection degree was 0.17%, 0.29%, 0.33%, and 0.32%, respectively, with a total area development rate of 4,213.39 m² y–1 and dissection degree development rate of 0.0125% y–1. From 2009 to 2012, 70.36% of gully areas increased, and 23.85% decreased. From 2012 to 2018, 56.29% of gully areas increased, and 43.31% decreased. From 2018 to 2021, 48.43% of gully areas increased, and 51.03% decreased. The area variation range in gullies gradually decreased from 2009 to 2021.
Table 3 Area distribution of gullies from 2009 to 2021