Spatial distribution of coastal sand dunes along the Cox's Bazar Coast, Bangladesh: relationships with grain size and vegetation cover

Coastal sand dunes along the Cox’s Bazar-Teknaf plain form shore-parallel ridges that buffer waves, surge, and relative sea level rise, yet they face accelerating pressure from tourism, shoreline change, and interrupted sand supply. This study characterizes their spatial distribution and zonation, and relates dune morphology to grain size and vegetation across the coast. The coastline was divided into five zones from Nazirartek to Teknaf and samples were collected from 44 sites. Dune dimensions were measured in the field and mapped with GPS; morphology was classified from foredunes to secondary forms. Sands were collected using an Auger instrument and analyzed by dry sieving after standard pre-treatment; pH and moisture were measured; and vegetation was identified using morphological traits verified against regional floras and databases. Results show a discontinuous belt of foredune, middune, and backdune ridges with blowouts and swales; foredunes are the highest and most exposed, and vegetation cover from pioneers seaward to established communities landward correlates with grain size, moisture, and exposure, indicating gradients in stability and maturity. Many sites are presently in an erosional phase that elevates risk to communities and coastal resilience. Policy should prioritize integrated dune management that combines ecological restoration with native vegetation, land-use controls, community participation, and continuous scientific monitoring to sustain the dunes’ coastal defense function and curb damage from poorly regulated development and tourism.