Quantitative estimation of sediment erosion and accretion processes in a micro-tidal coast

Abstract

Spatio-temporal cross-shore profiles and textural characteristics are the key parameters for understanding dynamics of the inter-tidal sedimentary environment. This study describes short-term dynamics of the inter-tidal sedimentary environment at beaches along the micro-tidal coast. Further a correlation is estimated in cross-shore morphodynamics and textural characteristics of surface sediments. The sedimentary environment is examined for a complete annual cycle using monthly collected cross-shore profiles and sediment samples. The Devbag beach (northern side) and Ravindranath Tagore beach (southern side) at the Kali river mouth, Karwar, west coast of India are characterized from extremely gentle to average slope, and broadly composed of unimodal sands. The sedimentary environment is significantly composed of textures having fine to medium sand, well to moderately sorted, fine to coarse skewed, and platykurtic to leptokurtic in nature. During the annual cycle a reversal pattern is observed between the two adjacent beaches, where a slower rate of sediment accretion is observed at Devbag beach while Ravindranath Tagore beach exhibited erosion. The beach dynamics along with the propagation of south-west (SW) and south-west-west (SWW) waves towards the coast significantly exhibit a dominance of northward sediment transport with the existence of a northerly alongshore current. In addition, the study reveals that an eroded beach may not be significantly identified composed of coarse grains. The poor correlation in morpho-sedimentary characteristics reveals the prediction of grain characteristics based on beach profile and vice-versa is unrealistic.