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Event-based runoff and sediment yield dynamics and controls in the sub-humid headwaters of the Blue Nile, Ethiopia
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  • Habtamu Assaye Deffersha,
  • Jan Nyssen,
  • Jean Poesen,
  • Hanibal Lemma,
  • Derege Meshesha,
  • Alemayehu Wassie,
  • Enyew Tsegaye,
  • Deribew Fentie,
  • Amaury Frankl
Habtamu Assaye Deffersha
Bahir Dar University College of Agriculture and Environmental Sciences

Corresponding Author:habtamuassaye@gmail.com

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Jan Nyssen
Ghent University Faculty of Sciences
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Jean Poesen
KU Leuven
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Hanibal Lemma
Bahir Dar University Institute of Technology
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Derege Meshesha
Bahir Dar University College of Agriculture and Environmental Sciences
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Alemayehu Wassie
Bahir Dar University College of Agriculture and Environmental Sciences
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Enyew Tsegaye
Bahir Dar University College of Agriculture and Environmental Sciences
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Deribew Fentie
Bahir Dar University College of Agriculture and Environmental Sciences
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Amaury Frankl
Ghent University Faculty of Sciences
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Abstract

Land degradation due to soil erosion presents a challenge for sustainable development. We investigated the impact of land use type and land management practices on runoff and sediment yield dynamics in the northwestern highlands of Ethiopia. The study area included 14 zero-order catchments with a surface area ranging from 324 m2 to 1715 m2. V-notch weirs produced from plastic jars were introduced as measuring alternatives that met local constraints. Runoff depth at the weir was registered at 5-min intervals during two rainy seasons in 2018 and 2019. Rainfall was measured using tipping-bucket rain gauges. Runoff samples were collected in 1-L bottles and suspended sediment concentration (SSC) was determined. The mean event runoff coefficient ranged from 3% for forests to 56% for badlands. Similarly, the mean annual sediment yield (SY) was lowest for forests (0.8 Mg ha-1 yr-1) and highest for badlands (43.4 Mg ha-1 yr-1), with significant differences among land use types (14.8 Mg ha-1 yr-1 in cropland, 5.7 Mg ha-1 yr-1 in grazing land, and 2.9 Mg ha-1 yr-1 in plantations). Soil organic matter (SOM) reduced runoff and SY, necessitating the consideration of agronomic and land management practices that enhance SOM. Annual SY decreased exponentially with the rock fragment cover (RFC). In fields where RFC was less than 20%, collecting rock fragments for installing stone bunds resulted in a net increase in SY. Rehabilitating badlands and enhancing SOM content in croplands can substantially reduce catchment SY and, hence considerably contribute to the sustainability of this type of environment.
17 Mar 2021Submitted to Land Degradation & Development
18 Mar 2021Submission Checks Completed
18 Mar 2021Assigned to Editor
07 Apr 2021Reviewer(s) Assigned
11 May 2021Review(s) Completed, Editorial Evaluation Pending
25 May 2021Editorial Decision: Revise Major
09 Jul 20211st Revision Received
10 Jul 2021Submission Checks Completed
10 Jul 2021Assigned to Editor
11 Sep 2021Review(s) Completed, Editorial Evaluation Pending
27 Sep 2021Editorial Decision: Revise Minor
25 Oct 20212nd Revision Received
26 Oct 2021Submission Checks Completed
26 Oct 2021Assigned to Editor
31 Oct 2021Editorial Decision: Accept