Non-Linear Responses to Land Use Change: Exploring Morphological Thresholds and Chaotic Signatures in the Ankobra River.

Abstract

River systems often display complex and seemingly random behaviours and patterns. This complexity may be attributable to the non-linear dynamics intrinsic to these systems, making them suitable for analysis through the lens of chaos theory. While natural processes contribute to chaotic behaviour, human land-use and land-cover changes significantly alter river systems by modifying sediment loads, flow regimes, and riparian vegetation. In this study, we examine how land-use and land-cover changes can act as perturbations, triggering or amplifying chaotic dynamics in river systems, using the Ankobra River basin as a case study. The research utilizes satellite imagery, remote sensing (RS), and Geographic Information Systems (GIS) techniques for spatiotemporal quantification of river channel form and LULC changes over three (3) decades (1991-2024). Specifically, Landsat images were processed and analysed using 5.6 ENVI and ArcGIS Pro. Findings reveal a significant and consistent increase in built-up areas over the different periods in the various sections of the river, coupled with a notable decrease in dense and sparse vegetation observed over much of the study period. The study concludes that the behaviour of river systems is on a continuous trajectory where future dynamics is dependent critically on present actions, past events, and conditions that exists in both upstream and downstream reaches.