LANDSCAPE architects from York have struck gold at the centenary Chelsea Flower Show with a stunning water roof garden.

The Landscape Agency, of Clifton Moor, co-designed the Royal Bank of Canada Blue Water Roof Garden in conjunction with University of Sheffield-based sustainable landscape design and “living roofs” specialist Nigel Dunnett.

It aimed to show how city centre rooftops could be used to actively manage rainwater to meet the dual challenge presented by water shortages and surface flooding risks.

It is the third consecutive year that the agency and Mr Dunnett had been commissioned to design a garden for the Royal Bank of Canada, having won Silver Gilt awards the previous two years.

Agency managing director Patrick James said he was “thrilled” to have won the gold medal. “It is the culmination of almost a year’s hard work by a dedicated team,” he said. “We were determined that this year should be a Gold, having just missed out for the previous two years.”

He said with extremes of drought followed by severe flooding, 2012 perfectly encapsulated the huge challenge facing society in managing water supplies.

“At times of low rainfall, it’s vital that we conserve every drop and make use of recycled ‘grey water’ where possible. “However, during periods of heavy rainfall, we must urgently address how to prevent surface water run-off and reduce the risk of flash flooding which causes heartache and expense to so many households and businesses.”

“We have demonstrated how city roof gardens have enormous potential to provide a realistic solution in helping us manage our water.”

The garden is based on an approach known as “skyrise greening”, which involves gardens on high rise buildings to provide residents with their own green outdoor spaces.

Previous agency projects in a wide variety of places include ones at the Yorkshire Sculpture Park and York Racecourse.