The Dee Estuary, located on the southern side of Liverpool Bay, in the Eastern Irish Sea, is macrotidalwith a peak spring tidal range in excess of 10m. The large tidal range and associated strong currentsmake the estuary a very dynamic system with large fluxes of sediment. River canalisation and landreclamation between 1700 and early 1900 has significantly altered the hydrodynamic and sedimentologicalconditions. This caused the main navigation channel to migrate from the eastern side to thewestern shore of the estuary. Large bed forms are visible in the intertidal zones of the mouth of the estuaryin aerial photographs. These features can be seen to be migrating into the estuary from X-bandradar images. Dune migration can lead to residual sand transport rates, depending of the directionand magnitude of the dune characteristics. It is therefore important to monitor the movement of theselarge scale bed forms to determine the stability of the complex area of sand banks and channels inthe Dee Estuary. Understanding the patterns of dune migration and associated sediment transport isfundamental for effective sediment management of an estuary, as well as an important considerationfor offshore construction. Monitoring the migration patterns of large scale bed forms in the mouth ofthe Dee Estuary will show if they correlate with the transport of sediment into the estuary and howmuch they contribute to the sediment budget of the estuary. The driving forces behind large scalebed form migration are investigated to determine whether it is the action of waves, tidal currents or acombination of the two which are important. ADCP deployments on West Kirby Sands show a strongflood dominant tide which could be indicative of a flood dominant residual sediment transport. A'three pronged' approach is taken to understand the migration of large scale bed forms in the mouthof the Dee Estuary. This includes remote sensing with X-band radar data, field measurements usingDGPS surveying and numerical modelling techniques. Modelling of the estuary using TELEMAC,validated with ADCP measurements at West Kirby Sands, shows flood dominant sediment transportover a tidal cycle. A 'model chaining' approach is taken to simulate tides, waves, wave generatedcurrents and sediment transport. Developments are made to include a variable bed roughness feedbackmethod into TELEMAC.