3.4 Estimation of ephemeral gully erosion volume and erosion
rate
Ephemeral gully erosion volume was calculated based on the VāLmodel using the length of 1,153 ephemeral gullies interpreted by remote
sensing images in 2009, with the ephemeral gully erosion volumes in 2009
and 2012 summarized in Table 4. In 2009, the total erosion volume of
1,153 ephemeral gullies was 10,257.60 m3, with an
average erosion volume of each ephemeral gully of 8.90
m3. In 2021, the total erosion volume of 2,312
ephemeral gullies was 19,175.95 m3, with an average
erosion volume of each ephemeral gully of 8.29 m3.
From 2009 to 2021, the ephemeral gully erosion volume change was mainly
in the south of the watershed (Fig. 7), where the terrain is broken and
has many steep slopes. In addition, the slope area has damaged soil
structure and less vegetation coverage after the gully land
consolidation project, so soil erosion can easily occur under extreme
rainfall. The average erosion volume of each ephemeral gully increased
by 3.54 m3 or 0.29 m3yā1, and the total erosion volume of all ephemeral
gullies (except for those that disappeared) increased by 8,918.35
m3 or 743.20 m3yā1 from 2009 to 2021.
Table 4 Ephemeral gully volume from 2009 to 2021 in the Zhoutungou
watershed.