A wave breaking against a sea wall causes high pressure gradients to act along the sea bed, pushing objects away from the wall. This situation is modelled using pressure impulse theory to show that, for a large object near a sea wall, the impulsive force due to the wave will move the object. This force can be found, given knowledge of the added mass and volume of an object. In particular, if th...

This paper introduces a 2 0 visual servoing technique for the station keepiirg of an unmanned underwater vehicle (UUV) with respect to planar targets on the sea bed. The underwater vehicle is subject to sea current disturbances which make it drift from its desired position. Feature points from unmarked objects are extracted and tracked with a sparse feature tracker developed in-house [I]. The s...

The goal of the Surface Heat Budget of the Arctic Ocean (SHEBA) program is to gain knowledge of the important physical processes in, below, and above sea ice in order to improve their representation in global climate models. In order to provide the community with a test bed for evaluating sea ice model components, we are attempting to make accurate estimates of the thickness distribution for th...

We provide a mechanistic explanation for observed metrics for drumlins, which represent their sizes and shapes. Our explanation is based on a concept of drumlin growth occurring through a process of instability, whereby small amplitude wave forms first grow as ice slides over a bed of deformable sediments, following by a coarsening process, in which the wavelength as well as the relief of the d...

A series of 18 flume runs were conducted in a 6-m long, 0.5-m wide recirculating flume with a bed gradient of 0.8% to determine the influence of obstruction shape on the formation and characteristics of forced pools. Six differentshaped obstructions were added to the flume with the maximum width of the obstruction held constant at 20 cm, which equaled a 40% constriction of flow. The obstruction...

Experimental results are reported for the bulk motion induced in a bed of granular matter contained in a cylindrical pan with a flat bottom subjected to simultaneous vertical and horizontal vibrations. The motion in space of the moving pan is quantified. A number of distinct bulk dynamical modes are observed in which the particle bed adopts different shapes and motions. At the lowest pan excita...

Why do ice streams exist on the Western Antarctic Ice Sheet, like near the Siple Coast? And what sets their width? They are streams of typically 30-80 km horizontal width, flowing rapidly towards the Ross Sea at hundreds of m.yr. The streams are bordered by slow moving ice, frozen to the bed, but no structure in the bed has been cited as controlling the location of the stream margins. We examin...

Abstract Scouring is a complex process dependent on several factors, and local scour more than general scour. This study was an attempt to predict round bridge piers based in the water stream. Three obstacle shapes were used – circular, round-nosed, elliptical as they are predominant hydraulic structures like piers. For each shape, depth measured around periphery for five gradually increasing d...

Information on bed topography and basal conditions is essential to developing the nextgeneration ice-sheet models needed to generate a more accurate estimate of ice-sheet contribution to sea-level rise. Synthetic aperture radar (SAR) images of the ice–bed can be analyzed to obtain information on bed topography and basal conditions. We developed a wideband SAR, which was used during July 2005 to...