Blue-Green Cities

The Blue-Green Cities Research Project was led by Prof Colin Thorne, University of Nottingham. Nine UK Universities were involved in addition to numerous academic, industry and local government partners.

Inundation modelling and influences of SuDS

We developed the CityCAT hydrodynamic model to better represent urban areas. This allowed us to:

• fully couple the surface flow model with a storm sewer network model
• represent key Blue-Green infrastructure such as blue-green roofs, permeable areas, swales, water butts
• carry out an ensemble of simulations addressing the uncertainty and variability in the characteristics of present and future extreme rain storms.

The Ouseburn catchment case study explored the influence of the Newcastle Great Park (NGP) SuDS ponds on the flow and sediment dynamics in the Ouseburn, a tributary of the River Tyne that runs through the NGP development.

We investigated how the SuDS ponds influenced three simulated flood inundation events:

• non-flood condition (5 year event)
• sewer design condition (30 year event)
• flood condition (100 year event).

We considered ‘with’ and ‘without’ SuDS ponds scenarios for the three events toassess the relative impact of the ponds. The simulation showed that the SuDS ponds attenuated and delayed the flood peaks for all three events, and that effects are more pronounced for higher magnitude events (e.g. 100 year). We also assessed the impact of the ponds on sediment dynamics for the three flood events. The ponds were shown to trap sediment during all three simulated flood events, thus meeting their design criteria.

Newcastle - the Demonstration City

In 2015, the Blue-Green Cities team transferred their research to Newcastle upon Tyne. Through discussion with the Newcastle Learning and Action Alliance, two areas were selected for detailed study:

• the middle Ouseburn and Newcastle Great Park
• the urban core and adjoining residential area of Wingrove.

We have a long-standing partnership with Newcastle City Council (Lead Local Flood Authority (LLFA) for Newcastle), the University Estates Department, Environment Agency and Northumbrian Water (NWL), who were keen to work with us to identify suitable measures for surface water management following the severe flooding in summer 2012.