Arcadis UK chief executive Alan Brookes will lead its new business following the acquisition of Hyder Consulting whose global chief executive Ivor Catto has stepped down.
The UK business will employ around 3,900 people and have turnover of around £280m.
Arcadis said Mr Catto had stepped down “in order to seek other business opportunities”.
Group CEO Neil McArthur said: “I would like to thank Ivor for his help in Hyder’s smooth transition to Arcadis and facilitation of the alignment of Hyder’s capabilities at both regional and global levels.
“Under his leadership, Hyder has successfully built the operating model based on global design excellence which was a major consideration for us when acquiring Hyder.
“I have great respect for his leadership and wish him well.”
Former Hyder UK managing director Graham Reid has been named as Arcadis global design director.
Mr Reid said: “We are already seeing the strength of the combined business with a significant win in Crossrail 2 and further successes anticipated in the future. I look forward to working across the whole Arcadis business to deliver best value for our clients.”
The group has also announced its new leaders in Australia Pacific and the Middle East.
Greg Steele will become regional CEO for Australia Pacific, Arcadis’s’ seventh region, having been Hyder MD in Australasia since 2010.
In the Middle East, Wael Allan has been named Arcadis CEO for the region.
Mr Allan was Hyder Consulting’s group operating officer and chairman for the Middle East.
John Williams will take up the role of COO and will lead a 2,200-person, £130m business in the Middle East.
Alan Brookes, Graham Reid, Greg Steele and Wael Allan will all join the group’s senior management committee.