Recurrence analysis of total suspended sediment and streamflows of Mahanadi River Basin, India

A comprehensive investigation into the nonlinear characteristics of daily streamflows and suspended sediment concentration offers valuable insights into river dynamics and the influence of hydraulic structures. This study explores the nonlinear behaviour of total suspended sediment (TSS) concentration and streamflow using recurrence plots and recurrence quantification analysis (RQA), with a specific focus on the impact of the Hirakud Dam in Mahanadi basin, India. Daily data from ten stations across the Mahanadi basin, spanning 15 years (1985–2000), were analysed. Results revealed that downstream stations exhibited lower determinism and maximum diagonal line lengths in recurrence plots for sediment concentration, suggesting reduced predictability and higher uncertainty in sediment dynamics. Conversely, upstream stations showed higher laminarity values, indicating prolonged periods of stable or low-variability sediment discharge. For streamflow data, most downstream stations (three out of four) displayed high determinism, indicating more regular and predictable flow patterns despite the dam’s presence. This contrasting result suggests that the Hirakud dam exerts a more pronounced influence on sediment behaviour than on streamflow. The findings underscore the differential effects of dam regulation on sediment transport and flow dynamics and point to the necessity of distinct, targeted management strategies to address sedimentation and hydrological stability in regulated river systems.