Application of Sediment Transport Model for Sand Management Project

In a coastal sediment management project sand borrow and placement activities can significantly modify nearshore bathymetry and lead to sediment movement and redistribution. The purpose of the study is to apply a coastal numerical model to calculate waves, current, tide, sediment transport, and morphology change, and to evaluate sediment movement around designated sand source areas and nearshore placement sites around a coastal inlet system. As sediment management alternatives are developed, the effect of major forcing conditions (hydrodynamics, waves, and wind) on sediment transport is determined, and the impact of sand borrow area selection on sediment balance and local morphologic changes is investigated. Model simulations show that sand mining tends to cause current changes and induce material accumulation around borrow areas. Relatively large backfilling occurs in nearshore sand borrow areas and sand removal in offshore borrow areas does not have significant impact on sediment transport fields due to weak currents. Model results also help identify the areas with net sediment losses or gains and indicate that sediment supplies can come from nearshore beach area or neighboring shallow area of a borrow site.