Soil Loss Estimation in Gullies of the Colônia Antônio Aleixo Basin, Manaus, Amazonas, Brazil

Abstract

Gullies in urban environments pose challenges to urban land-use planning due to their rapid development and the impact they cause on infrastructure and the physical environment. This study aimed at monitoring four gullies located in Colônia Antônio Aleixo watershed, in Manaus, Brazil, to analyze their morphometric characteristics and to estimate associated erosion rates. The study was based on cartographic records from 2006, 2012, and 2016, complemented by Unmanned Aerial Vehicle (UAV) surveys conducted in 2017 and 2020. The high-resolution imagery provided detailed information on the erosive features, while fieldwork supported data validation. The results indicate widening of the gullies and reduction in their depth, due to internal sediment deposition. Edge retreat also led to the coalescence of adjacent features. UAV monitoring made it possible to identify secondary landforms associated with reworking processes, such as headcut alcoves and small erosional channels. It is concluded that topographic profile analysis is an effective approach for understanding the morphology and evolutionary dynamics of gullies in urban environments.