Remote-sensing perspective and GPR subsurface perception on the growth of a recently emerged spit at Talashil coast, west coast of India

Abstract

The growth as well as the internal structure of the recently emerged Talashil spit along the west coast of India was studied using multidate satellite images coupled with ground-penetrating radar (GPR) information. Decadal changes (2003–2013) in configuration, geomorphology and erosion and accretion pockets along the spit were traced and compared. A 170 m long subsurface profile across the spit from shoreline to river shore was generated using GPR. Historical satellite images from 1973 to 2013 illustrate a rapid transformation of a linear sand bar into a matured spit. The growth trend over the period 2003–2013 shows mainly accretion along the seashore and erosion along the river shore. Three dynamic hot spot locations were noticed where erosion and accretion were alternately dominating. The radar facies clearly distinguishes zones of fluvial, dune and inter-tidal dominance and substantiates the interpretation of the satellite images. This study indicates spit formation following build up and emergence of a submerged shoal due to fluvial sedimentation, after which an equilibrium between erosion and accumulation was reached. The data indicate that the growth of the spit has reached its mature stage and only lateral oscillation of the spit is likely in the future unless sizable disturbances caused by either tectonic or anthropogenic processes influence this region.