Measurements of sea bed ripple evolution in an estuarine environment using a high resolution acoustic sand ripple profiling system

To predict suspended sediment dynamics a knowledge of sea bed roughness is generally required. This measurement has traditionally been difficult to obtain when significant amounts of suspended sediments are being transported. However it is now becoming possible to characterise the form of the sea bed, and its evolution, in-situ using high resolution acoustic techniques. In the present work, time series of two dimensional backscatter slices taken vertically through the water column have been produced using a high resolution 2 MHz rotary scanning sonar. The data were recorded over a number of flood tides in an estuarine environment, and signal processing techniques were subsequently used to pick out the position of the bed from the resulting images. Analyses of the sand ripple profiles are given over time and show the evolution of the sand ripples in terms of wavelength, amplitude and migration rate