The use of Remote Sensing and GIS Methodology in the Analysis of Urualla Gully Erosion site Imo State Nigeria

Abstract

The study of Urualla gully erosion is currently undermined by the inherent costs associated with consistent field monitoring and the lack of historic measurements to perform time series analysis. Remote sensing methodologies, via the Landsat archive, are used as a low-cost data source to allow analyses of gullies over the time period 2006 to 2021. In conjunction with longterm environmental variables, the Landsat data is used to establish land cover changes over the time period, via pixel-based classification, to identify its role in gully development. Aiming to link environmental characteristics and land cover changes with Urualla gully development and its rates of change, Digital Elevation Models (DEM) and remote sensing imagery are used to detect topographical and landscape characteristics and to calculate gully dimensions. Landscape analysis over the study period reveals a steady increase in Gully/Open land. The increasing area of Urualla gully consistently correlates with vegetation loss, (r= -0.97 (p<0.05)) and also, when correlated with Built-Up Area over the same period of time, the correlation shows (r= 0.97 (p<0.05). Analysis of study area topography at 30m resolution reveals that Urualla gully site developed on high slope of more than 400 . The study offers a method of monitoring Urualla gully development from early stage to maturity and exemplifies the complexity and variability of erosion drivers in the study area. It presents a verified approach in the monitoring of gullies, enacted through use of low budget/computing cost remote sensing and classification technologies, and serves to embolden civilian and governmental efforts to manage the societal and environmental menace of gully erosion.