Restoration intervention effects on gully geometry and runoff characteristics at Meqebesa sub catchment in southern Ethiopia

Abstract

Gully restoration intervention efforts are critical for erosion and morphology management. Restoration activities are implemented to regulate gully development, runoff velocity, soil loss, and sediments. This study aims to investigate the effects of restoration interventions on gully geometry and runoff characteristics. Being the first effort in the region, this study analyzed these alterations by comparing the before and after condition based on on-site measurements of gully characteristics and surveys conducted from June 2023 to April 2024. The study carried out field measurements of gully geometric parameters such as width, depth, slope, and cross-sectional area in different phases between June 2023 to April 2024. Additionally, runoff characteristics, including runoff velocity, force exerted on the gully bed material, and erosion rate, were also quantified. The findings indicate that restoration interventions have high contributions to reduce gully bed slope up to 15%, gully depth up to 18%, and gully volume up to 15% by stabilizing gully morphology. Additionally, runoff velocity, shear stress force, and erosion rate were reduced by 44%, 26%, and 15%, respectively. The findings demonstrate that restoration interventions play a critical role in changing gully morphology and regulating runoff processes. Over all, the results highlight the importance of integrating restoration strategies to regulate the effects of gully development. More generally the outputs from this study can support the regional stockholders in the planning of watershed management. Gully restoration intervention highly alters gully morphology and runoff characteristics. Intervention changes the gully morphology by 15–18%, and runoff characteristics from 15 to 44%. The intervention measures have reduced gully volume by 15%. Gully restoration has substantially reduced runoff velocity, shear stress force, and erosion rate.