Abstract:
This research investigated the extent of gully head retreat and the effectiveness of
rehabilitation measures on vegetation recovery in the Debremewi watershed in Northwestern
Ethiopia, a region vulnerable to severe land degradation due to gully erosion. The study
aimed to quantify gully head expansion, evaluate vegetation cover dynamics using the
Normalized Difference Vegetation Index (NDVI), and estimate soil loss caused by gully
erosion. High-resolution imagery from Google Earth Pro was utilized to assess gully head
retreat over a five-year period. Initially at 2010, 35 gullies were identified, which expanded to
38 as a result of upward movement and lateral splitting after five years from existing gullies
on 2015. By 2020, interventions reduced the number of actively retreating gullies to 12.
However, a slight resurgence in gully expansion was observed after 2020. Vegetation cover
was analyzed using Sentinel-2A imagery over three time intervals from 2016 to 2024. Results
revealed that watershed management interventions significantly enhanced vegetation cover, as
indicated by increased NDVI values. Nonetheless, the termination of these interventions after
2020 led to accelerated gully formation, increased soil loss, and a decline in vegetation cover.
For the past four consecutive years, the total estimated soil loss from gully erosion was
approximately 70,834 tons, or 94 tons per hectare, which are 23.5 ton in per year. In
conclusion, while initial interventions successfully mitigated gully expansion and promoted
vegetation growth, sustainable outcomes require continued maintenance and communitybased
land
management.
This
study
highlights
the
necessity
of
long-term,
locally
led
strategies
to
maintain
ecosystem
restoration
in erosion-prone
areas.