Changing Dynamics of the River Channel and Its Segments: A Spatio-Temporal Analysis of the Periyar River, Southern India

Abstract

Riverine systems are increasingly affected by natural processes and human activities, leading to significant morphological changes. Understanding these changes is essential for sustainable river management and disaster risk reduction. This study aims to analyse the spatio-temporal morphological changes of the Periyar River over a 67 km stretch in Ernakulam District, focusing on sinuosity, erosion–accretion patterns, and channel shifts using GIS and remote sensing techniques. It adopts a longitudinal geospatial analysis using historical maps and satellite imagery. The methodology involved dividing the river stretch into eight sections (A–H) and analysing morphological changes through GIS and remote sensing tools, with parameters such as sinuosity index, erosion and accretion areas, channel shifting rates, and valley index quantified and compared across time periods. The results indicate a northward shift of the river, with the sinuosity index increasing by 20.28% (from 1.09 to 1.31) and a net accretion of 1,535.63 hectares; Section E exhibited the highest sinuosity (2.33–2.50) along with a 23.8% increase in erosion, while Section D showed the highest dynamism with a shifting rate of 1.40 hectares per year, and the valley index decreased from 1.30 to 1.07, indicating valley narrowing, with the highest erosion recorded during 2008–2023 (221 hectares), largely influenced by urbanisation and altered sedimentation patterns. The study concludes that significant geomorphic transformations are driven by both natural and anthropogenic factors, and emphasises the need for targeted interventions such as riparian vegetation restoration and controlled urban development in high-risk zones to stabilise riverbanks and reduce flood risks, while also providing a replicable framework for sustainable management of dynamic river systems.