Ephemeral gully erosion is a primary mode of soil erosion that is highly
visible, affecting soil productivity and restricting land use. Watershed
is the basic unit of soil erosion control; existing research has focused
on several typical ephemeral gullies or slopes, which do not fully
display changes in ephemeral gullies at a watershed scale. This study
analyzed the spatial-temporal evolution and development rate of
ephemeral gully erosion at the watershed scale on the Loess Plateau from
2009 to 2021 using remote sensing images (0.5 m resolution), unmanned
aerial vehicles (UAV), and field investigations. The results revealed
that: (1) most ephemeral gullies occurred in southwestern parts of the
watershed, with many hills and large slope gradients; (2) average growth
rates of each ephemeral gully frequency, length, density, dissection
degree, and width were 2.87 km y
, 1.66 m y , 0.12 km km
y , 0.0125% y
, and 0.04 m y ,
respectively; (3) ephemeral gully erosion volume ( V) and length
( L) had a good power function relationship: V = 0 . 0842 L 1 .
1932 ( R 2 = 0 . 80 ) . The root mean square error (RMSE) and
coefficient of determination (R ) between the
measured and predicted ephemeral gully volumes suggest that the
V–L relationship has a good predictive ability for ephemeral
gully volume. Thus, the V–L model was used to evaluate the
development rate of ephemeral gully erosion volume in small watersheds
from 2009 to 2021, revealing an average value of 743.20 m
y . This study proposed a
feasible model for assessing ephemeral gully volume and volume changes
at a watershed scale using high-resolution remote sensing images,
providing a reference for understanding the development of ephemeral
gully erosion in small watersheds over time.
Gully erosion is one of the main modes of slope erosion on the Loess
Plateau, which plays a connecting role in the slope gully erosion
system. The Loess Plateau has wide and densely distributed gullies. The
study selected a typical small watershed in the hilly and gully region
of the Loess Plateau to measure the morphological characteristics and
spatial-temporal distribution of gullies. A deep learning image semantic
segmentation model was used to identify and extract the morphological
features of gullies at the watershed scale from 2009 to 2021 based on
remote sensing images (0.5 m resolution) and then analyze their temporal
and spatial distribution characteristics. The results revealed that: (1)
most gullies occurred in the hilly southern parts of the watershed,
which has complex landforms and large slope gradients; (2) gully number
increased from 1,159 in 2009 to 2,312 in 2021 (average 97 per year),
with a frequency development rate of 2.87 km y
; (3) gully length generally ranged from 25–40 m,
with an average growth rate is 1.66 m y and
density development rate of 0.12 km km y
; (4) gully width ranged from 0.5–1.5 m, with an
average growth rate of 0.04 m y . (5) the total
gully area increased from 0.0566 km² in 2009 to 0.1072 km² in 2021, with
a development rate of 4,213.39 m² y and dissection
degree development rate of 0.0125% y . This study
provides a theoretical and scientific basis for gully erosion control
and eco-environmental protection at the watershed scale on the Loess
Plateau.
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