The Ontogeny and Mitigation of Gully Erosion in the Coastal Plain Sands of Uyo, Southeastern Nigeria: A Comparative Field Assessment

Gully erosion constitutes a major environmental challenge in southeastern Nigeria, particularly within the coastal plain sands of Uyo where fragile soil conditions, intense rainfall, and rapid urbanization interact to accelerate land degradation. This study investigates the ontogeny (developmental stages), spatial dynamics, driving factors, and mitigation of gully erosion through a comparative field assessment. A mixed-method approach was adopted, integrating field measurements, geospatial techniques, and a survey of 350 sampled observations across ten locations. Findings reveal that gully erosion in the study area is predominantly in advanced stages, with 60% of observed gullies classified as mature or advanced, indicating extensive geomorphic development and persistent erosion processes. The study identifies high rainfall intensity (100%) and sandy soils (88.6%) as primary natural drivers, while poor drainage systems (78.9%), deforestation (70.9%), and urbanization (63.1%) significantly intensify erosion. Spatial analysis shows a higher concentration of gullies in urban (45.1%) and peri-urban (32.0%) areas, underscoring the influence of land-use change. Morphological characteristics indicate deep (mean: 4.8 m), wide (7.3 m), and elongated (56.2 m) gullies, reflecting both vertical incision and lateral expansion. Although engineering measures are the most common mitigation approach (40%), their effectiveness is limited, with 40% rated as poorly effective due to inadequate design, maintenance, and lack of integration. The study highlights a strong preference for sustainable strategies, including improved drainage, afforestation, and integrated watershed management. It concludes that gully erosion in Uyo is a dynamic and human-amplified process requiring holistic, context-specific, and multi-scalar interventions. The research contributes to improved understanding of erosion dynamics and provides a basis for sustainable land management and policy development in coastal plain environments.