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A multi-method approach to analyze changes in gully characteristics between 2009 and 2018 in southeast Nigeria
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  • Ikenna Osumgborogwu,
  • John Wainwright,
  • Laura Turbull,
  • Luke Uzoigwe
Ikenna Osumgborogwu
Durham University
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John Wainwright
Durham University
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Laura Turbull
Durham University
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Luke Uzoigwe
Imo State University
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Abstract

Gully erosion is the dominant environmental problem in southeast Nigeria and has led to loss of human and material resources. In this study, we evaluated changes in gully characteristics in southeast Nigeria between 2009 and 2018 using a multi-method approach including geotechnical investigations, analysis of high-resolution satellite imagery (2 – 5 m) and focus group discussions. Gully numbers increased from 26 to 39 and mean gully length increased from 0.39 to 0.43 km. We found that the soils in the study area have low cohesion and high sand content which make them susceptible to dispersal by erosive forces. Land adjacent to rivers had the highest concentration of gullies, and there was a sharp rise in slope from 10 – 58.2% within a distance less than 500 m from the river. Regarding potential gully-drivers, land-use changes were observed. Non-vegetated lands increased from 58.6 km2 to 144.7 km2 between 2009 and 2018, while reductions in fallowed lands from 281.2 km2 to 57.8 km2 were observed. Results from focus group meetings indicate there was no gullying in the area before the Nigerian civil war. Although war-time activities which led to initiation of oldest gullies have ceased, land-use changes likely increase volume of surface runoff. We infer that interactions between soil conditions which potentially enhance seepage erosion and higher surface runoff resulting from land-use changes have propagated gullying in the study area post-civil war.

Peer review status:IN REVISION

24 May 2021Submitted to Land Degradation & Development
29 Jun 2021Submission Checks Completed
29 Jun 2021Assigned to Editor
12 Jul 2021Reviewer(s) Assigned
23 Jul 2021Review(s) Completed, Editorial Evaluation Pending
30 Aug 2021Editorial Decision: Revise Major
06 Sep 20211st Revision Received
09 Sep 2021Assigned to Editor
09 Sep 2021Submission Checks Completed