Meander geometry characteristics as a response to hydraulic and lithologic control in the active floodplains of Lower Nagar basin

Abstract

ABSTRACT The present work aims to evaluate the controlling factor of meander geometry in the alluvial rivers. The assimilation of lithologic and hydraulic analysis of the meandering channels puts new insight to the understanding of the meander geometry. The study compares two highly contrasting meandering rivers of Nagar and Kulik in the Lower Nagar Basin, India. To assess the connection between the meandering nature with the hydraulic and lithologic factors, extensive field survey was made during the bank-full monsoon period. The principal component analysis between the hydraulic variables and meandering components suggests that the hydraulic factors of Nagar more effectively control the bend structure of the river, whereas the lithology of the Kulik river controls the meandering planforms. The meander patterns have shown significant transition flowing over different lithologies of grainsize combinations. The statistical prediction based on the hydraulic functions was used to predict the future possible changes in meandering planform. Moreover, the implication of the result was validated with the past century changes and thus can be suitable for the river management practices. In general, the meandering dimensions (in terms of λ, Am and Rc) are found to be maximized when finer materials are prevalent and vice-versa.