INNOVATIVE FUTURE-PROOFING IN HILLERØD	11/06/2009
	The violent downpours of the summer of 2007 caused many instances of flooding. In Hillerød, an entire residential area was flooded. For purposes of reducing the risk of flooding to the home owners affected, the local authorities have analysed this incident. Experts estimate that, due to the climate changes, such extreme downpours will occur much more frequently in the future. Hence, Hillerød Municipality has initiated a series of initiatives in order to avoid instances of flooding similar to those experienced in 2007 where several areas were submerged. Model calculations for the drainage conditions of one of the residential areas affected show that, in this case, enlarged drain pipes will not be sufficient to reduce the risk of similar flooding. This is why Hillerød Municipality is now investigating the feasibility of action on two other fronts: the possibility of building small dams in a forest area, thus keeping back and delaying the water and the possibility of making minor changes in the terrain to deflect the water from the houses. This would minimise the risk of the exposed houses being hit again – and this relatively inexpensively. 3-D modelling In connection with this project, we were in charge of advanced modelling by means of linked 3-D surface models and models of the drainage systems in the area. Thus, we were able to analyse the flooding and precisely establish its cause. The same model is used for determining how the climate changes will influence the risk of flooding and how the risk of similar occurrences of flooding can be best and cheapest reduced or remedied. Using e.g. advanced cartographic analyses and 3-D surface modelling, Grontmij | Carl Bro is assisting a number of municipalities in climate-adaptation projects. Further information Uffe Gangelhof, Engineer, Grontmij | Carl Bro, Telephone +45 4348 4709, Uffe.Gangelhof@grontmij-carlbro.dk