To evaluate the annual sediment dispersal pattern, a year-long beach profile monitoring and granulometric analysis were adopted along the Kundapura estuarine beaches of coastal Karnataka. The river mouth is bounded by breakwaters and the coast is armoured by seawalls and groins. Beaches adjacent to the breakwater showed progradation as a result of the shadow zone created due to the sheltering effect from incident waves. Evidence also comes from the replacement of coarser mode sediments by finer. Those away from the shadow zone, however, experienced extensive erosion. They are subjected to along-shore drift and minimal replacement from the same. It was also observed that despite being tropical estuarine beaches, sediments did not show any affinity towards a Cuvial-derived character. These points towards transport of fine sediments further offshore and retention of coarser fraction in the surf zone that is to be carried shoreward. Breakwaters in turn facilitate this by channelising the river discharge farther in the sea. Evidence towards the same is also provided by the well-sorted to moderately well-sorted nature of the sediments. Breakwaters were thus observed to highly influence the sediment dispersion and distribution along an estuarine coast. This study will provide knowledge on the role of coastal structures in sediment dispersion while framing future coastal protection strategies for the conservation of the coast.
$\bullet$ Progradation of beaches adjacent to the breakwaters due to sheltering from direct waves whereas erosion of beaches away from the influence of these structures is observed.
$\bullet$ Extensive engineered coast has resulted in the narrowing of the natural beach width making it reflective with a high-energy environment thus accelerating further erosion. Due to this, the beach has lost its recreational value.
$\bullet$ The along-shore drift directions derived considering beach morphology, beach volume change and beach sedimentology, along with the mode of transport and environmental affinity of sediments provide a comprehensive understanding of sediment dispersal pattern along the coast.
Volume 132, 2023
Continuous Article Publishing mode
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