Short-term observation of beach dynamics using cross-shore profiles and foreshore sediment

摘要

Cross-shore beach profiles and textural characteristics of foreshore sediment were analyzed for understanding an annual cycle of intertidal beach dynamics at Devbag, an Island sheltered estuarine coast. This study is carried out as response to the shoreline management project proposed by Ministry of Earth Science, India. Cross-shore transects were monitored in a monthly interval during February 2008 to February 2010 along with collection of beach surface sediment samples. Change in beach volume over an annual cycle showed a slow rate of sediment accretion at the Devbag beach where the maximum accretion was found at dissipative zone. During the year 2008-09, the volume of sediment accretion was 24.23 m~3/m with an average beach width and slope of 91 m and 3.3° respectively. During 2009-2010, the accreted beach volume was 33.54 m~3/m with an average beach width and slope of 132 m and 2.6° respectively. The beach along the coast was varying from extremely gentle to a slightly steeper slope which showed dissipative to reflective nature. The Beach was dominated by both fine and medium sands. More quantity of unimodal and bimodal sediment was found with moderately well sorted and moderately sorted nature. No significant correlation in beach morpho-sedimentary characteristics was found due to the non-uniform trend in beach morphodynamics and textural characteristics. Present study emphasizes the need to observe the beach changes over inter-annual seasons before planning coastal protection measures. The results of the study will be helpful for formulating an effective coastal zone management plan at Devbag, Kali estuary, west coast of India.