A new model of the Severn estuary built in Cardiff University will be used to study the impact of tidal power plans, including a barrage.
The model, which is close in design to the basin, stretches from the west of Carmarthen Bay to Gloucester and was funded by the assembly government.
It will enable researchers to look in depth and long term at possible impacts on aquatic environments and habitats.
The barrage could extend from the south Wales coast to Weston-super-Mare.
A feasibility study by the Welsh Assembly Government and the UK Government into the Severn Barrage, which could produce about 5% of the UK's electricity within 14 years, was announced in January.
It would harness the tidal power of estuary using a hydro-electric dam, but filled by the incoming tide rather than by water flowing downstream.
One option for a Severn Barrage would stretch from Lavernock Point to Brean Down and is estimated to cost around £15bn.
The model has been designed and built by researchers at the Cardiff School of Engineering and Swansea University to resemble as closely as possible all the unique characteristics of the estuary.
It will enable them to produce improved computer simulations of flooding patterns, inter-tidal habitat area changes, and sediment transport and bed changes, such as erosion and deposition.
They will also be able to model changes in beaches and general water quality characteristics such as light intensity in the water column, nutrients and faecal bacteria levels with and without the proposed barrage.
The model of the estuary features a computer generated oscillating weir which is used to generate tides of varying amplitude.
The barrage would stretch from south Wales to the Somerset coast
It also has a removable model barrage that allows the conditions prior to, and after, the construction of the barrage to be simulated.
It also allows for the impact of other tidal energy devices, including tidal lagoon and tidal stream turbines, to be examined.
Professor Roger Falconer, who led the team designing and building the model, said it would be used to double check the information garnered from computer simulations of the impact of a barrage or other tidal power proposals.
"It will help us make the right decision as to how we can minimise any adverse environmental impacts," he said.
After unveiling the model, Sustainability Minister Jane Davidson said the findings of the research would inform the feasibility study.