Multi-scale comparison of Topographic Wetness Index for Soil Erosion Assessment

Abstract. Soil erosion remains a complex environmental phenomenon with broad implications for ecosystem stability and land management. The topographic wetness index (TWI), a commonly employed indicator in hydrological and geomorphological modeling, plays a crucial role in understanding how moisture distribution influences erosion potential. Despite its widespread use, TWI's theoretical grounding in multi-scale erosion assessment remains underexplored. Existing literature tends to focus on empirical applications at isolated spatial scales, often overlooking scale-sensitive behaviors and theoretical consistency. This study develops a conceptual framework for understanding the scale dependency of TWI in soil erosion modeling. It explores the assumptions underpinning TWI, its mathematical structure, and its interaction with scale-related processes by interacting with theoretical perspectives from geomorphology, hydrology, and spatial analysis. The study proposes a theoretical model for evaluating TWI's suitability across scales, identifying key factors that influence its performance. This framework aims to inform more robust and theoretically grounded applications of TWI in soil erosion assessment, paving the way for improved model transferability and sustainable land management practices.