Estimating nearshore bedform amplitudes with altimeters

Abstract

Estimates of the heights of large (0.1-0.4 m heights and 1-10 m horizontal lengths) migrating bedforms on a sandy beach made with fixed, single-point altimeters are similar to heights estimated from profiles across the bedforms made with altimeters mounted on an amphibious vehicle that traversed the surf zone. Unlike many profiling systems, the robust, fixed altimeters can measure bedforms in bubbly, sediment-laden surfzone waters nearly continuously, including during storms, thus allowing investigation of the relationships between bedform heights and near-bottom velocities to be extended to a wide range of wave conditions. The fixed-altimeter observations of migrating bedforms suggest a sandy surfzone seafloor is not always smooth during energetic conditions with strong mean currents and large wave-orbital velocities.