Jeopardizing the environment with beach nourishment

Grain size distribution of modern beach sediments in Sri Lanka

“…2b). For example, the lower standard deviation values indicate well-sorted samples under low-energy depositional conditions (López 2017;Yun et al 2023). The sorting values of the southwest region of Sri Lanka range from 1.307 to 2.104, with an average of 1.621 (Table 1), suggesting moderately sorted samples (Fig.…”

“…Therefore, the mean grain size is an indicator to explain the energy of deposition environments. Generally, the finer sediments are found in a low-energy regime and the coarser sediments are found in a high-energy environment (Bhattacharya et al 2016;Saengsupavanich et al 2023).…”

“…Beach nourishment is the process of depositing additional sediment on or near the beach to enhance beach safety and protect buildings and infrastructure from wave attacks (Dean 2002;Hamm et al 2002;McLachlan and Brown 2006;de Schipper et al 2021;Saengsupavanich et al 2023). Coastal erosion and reduced sediment supply are major natural threats to the coastline in Sri Lanka (Amalan et al 2018;Ratnayake et al 2018;Gunasinghe et al 2021).…”

“…Sediment compatibility is one of the main factors to consider in beach nourishment projects, and it refers to the degree of similarities between nourished sediments and native sediments (Dean 2002). There are various methods for quantifying compatibility, some of which consider only the mean or median diameters of native and borrow materials and some of which consider other parameters such as grain size distributions for sorting (Dean 2002;Saengsupavanich et al 2023). In more traditional usage, the grain size of nourishing sediments needs to be equal in size to original/native beach sediments (van der Wal 1998;Hartog et al 2008;Castelle et al 2009).…”

“…For example, beach nourishment (i.e., additional sediments place on or near the beach to protect coastal structures) improves beaches for recreation, and creates new habitats/ecological values (Dean 2002;de Schipper et al 2021). Sediment grain size is a critical parameter in the beach nourishment process, affecting (i) stability (larger grain sizes like gravel, and cobble are resistant to erosion), (ii) beach profile (selection of sediment grain size depends on the desired beach profile), (iii) habitat (coarse sediments provide better habitat for larger organisms like crabs, whereas fine sediments provide better habitat for smaller organisms like worms), and (iv) cost (coarse grains are generally having high operation cost) (Ratnayake et al 2019;Gunasinghe et al 2022;Saengsupavanich et al 2023).…”