City of Bradford Metropolitan District Council Leeds City Council Yorkshire Water

1. Making space for waterIntegrated Urban Drainage pilotsRiver Aire Strategic StudiesPreliminary results City of Bradford Metropolitan District Council Leeds City Council Yorkshire Water Environment Agency Pennine Water Group, Universities of Bradford and Sheffield

2. The challenge To provide information to facilitate a sea change in behaviour

3. What if? • The global carbon economy continues to expand unabated until constrained by the economies of scarcity? • Densification of our urban areas continues at the same rate as it has done for the past 50 years? • The management of our urban drainage systems continues as it has done for the past 50 years?

4. Pressures • Up to 20% increase in rainfall depth by 2085! • Up to 20% increase in rainfall intensity by 2085! • Up to 20% increase in impermeable area by 2055 if we don’t alter the way that we manage our urban landscape! • Up to 30% more space occupied by buildings by 2055 • Up to 20% reduction in infiltration to groundwater overall by 2055 and up to 40% reduction when urban green space is excluded! • Up to 40 increase in temperature of receiving waters in summer coupled with reduced base flows!

5. States • Ofwat and the Environment Agency will continue to regulate inflexible nationally driven campaign based investment programmes with set deliverables identified on a five yearly basis. There will be little funding available for large scale upgrading of urban drainage systems • Government refuses to legislate to define responsibilities such as the adoption of SuDS or to provide real guidance for brownfield development • Local authorities will continue to be under-funded and under staffed in relevant disciplines and so will not be able to address the emerging problems • As a result of this developments go ahead using conventional piped drainage systems with little concern for the management of excess flows

6. The study area

7. Urban impacts

10. Potential doubling of the frequency of flooding due to climate change at a given location • Potential doubling of the frequency of flooding due to urbanisation at a given location • Potential quadrupling of the frequency of flooding due to combined impacts

11. River impacts • Up to 15% increase in peak spill to receiving waters due to climate change during extreme wet weather, but unlikely to coincide with river peak • Up to 80% increase in spill volume due to climate change at drainage area scale for twice yearly summer rainfall • Up to 10% increase in flow to full treatment due to climate change during wet weather

12. Tales of the river bank • Interaction between the river and the sewers

13. 10 year 120 minute rainfall with free outflow No flood defense With flood defense With flood defense and flap valves

14. 100 year river level with 10 year rainfall 120 minute 360 minute No flood defense With flood defense With flood defense and flap valves

15. 100 year river level with 30 year rainfall 120 minute 360 minute No flood defense With flood defense With flood defense and flap valves

16. The way forward • The analysis is providing compelling evidence to change the way that things are done. • Planners want to know where the predicted flooding is likely to occur so that they can either • Avoid specific areas • Develop suitable policy to allow development • There are concerns over issues relating to blight of properties, so Defra needs to insist that the models and/or the results of the simulations are made available. • The outputs indicate where more detailed modelling is required.

17. The AUDACIOUS approach (a framework for urban storm and surface water management)

18. Urban flood risk management and the land and water planning frameworks – the storm and surface water management plan and the land and water management plan