Remote sensing of sand distribution patterns across an insular shelf: Oahu, Hawaii

Sandy substrate is important as a resource, habitat, and dynamic region of the bathymetry. We find that sand storage across the insular shelf of Oahu, Hawaii is controlled most strongly by general insular shelf morphology and to a lesser degree by hydrodynamic energy. Shelf sand is predominantly found in water depths less than or crossing the 10 m contour. We use remote sensing to identify and classify 14,037 individual sand deposits in nine study regions. A supervised classification algorithm aggregates these into five classes with 14 subclasses. Almost 63% of all sandy surface area falls into two subclasses of the Channels and Connected Fields class, 1) Major Channels and 2) Unchannelized Drainage. These subclasses connect regions of sediment production to regions of sediment storage on the insular shelf surface. This study is the first to quantitatively analyze and classify shelf sand deposits, in a high volcanic island coral reef setting.