Short-term estimation of beach sedimentation pattern in the mixed-energy environment at Digha coast, India

The short-term, long-term and seasonal hydro-morphodynamics and associated sedimentation patterns need to assess in prior aspects concerning the beach nourishment in the erosive coast. However, only the long-term and seasonal beach sedimentation patterns have been studied considering the monsoon phases in the Digha coast. In this study, the field investigation was conducted for 15 days during the 10–24 March 2018 to understand the morphodynamics, hydrodynamics and sedimentation pattern in the meso-tidal and wave-dominated mixed-energy environment in three different beach zones according to tide level. Beach bathymetry survey, wave hydrodynamic measurements and sediment sampling was done coupling with the empirical formulation of data through the geo-statistical methods. The high, moderate and low level of wave dynamics are observed in zone 3, 1 and 2, respectively. The resultant depth of closure varies from 0.94 to 1.28 m according to the fluctuating tide level. Along the four cross-profiles in-between the low-tide level (LTL) and high-tide level (HTL), the sedimentation pattern reveals the accretion in zone 1 (~ 0.81 cm) and 3 (~ 0.11 cm), while meager erosion in zone 2 (~ 0.02 cm). Such type of sedimentation pattern synchronizes with the net sediment volume detained by swash and backwash, which indicates a surplus volume in zone 1 (~ 50.09 gm) and 2 (~ 132.36 gm), and deficit (~ 52.62 gm) in zone 3.