International approaches to the hydraulic control of surface water runoff in mitigating flood and environmental risks

Transcription

1 International approaches to the hydraulic control of surface water runoff in mitigating flood and environmental risks AWRA2016 (Orlando) David Powers (Woods Ballard, Udale-Clarke, Kellagher, Dou, Gerolin, McCloy, Schmitt)

2 Introduction Drivers for more sustainable approaches to managing surface water runoff The evolution of design criteria A quick look at international variations UK design resources and tools Supporting evidence for robust design Thoughts on future needs.. Page 2

3 Flooding & erosion Pollution Urban heat stress Water availability Urban heath & wellbeing Biodiversity & green space Liveability Page 3

4 Evolution of criteria from to Page 4

5 .. to.. Green corridor / ecological value / community education Building temperature regulation / air quality improvement Rainfall as a resource Recreational public space Multi-functional parking space Traffic calming

6 UK (SuDS) Manage surface water for maximum benefit Page 6

7 UK Sustainable Drainage Systems (SuDS) Non-statutory design standards and guidance

8 Germany (water sensitive drainage) Pluvial flood risk management for urban drainage systems (DWA 2015a) Local water balance as a benchmark for water sensitive drainage (DWA, 2006) DWA-A 102 (DWA, 2015b) (in preparation) will require the evaluation of wet-weather-flow in terms of its pollution load and impacts on receiving water s Floodrisk 2016 needs Bridget Woods Ballard (b.woods-ballard@hrwallingford.com)

9 France (stormwater management) Graduated levels of service for stormwater management systems (Certu, MEDD, 2003 and DGALN et al., 2014). Demonstration of rainwater zoning specified by the City of Paris

10 China (LID, Sponge Cities) Sponge City Construction Technical Guidance (Ministry of Housing, PRC 2014)

11 USA (BMPs > LIDs > Green Infrastructure) Local / state / federal criteria all vary Quality control focus: via treatment of specified rainfall depth via volumetric removal of specified rainfall depth (addressing contaminant loads + combined sewer overflows)

12 UK design resources: comprehensive guidance Principles Process Engagement Costs and benefits Submissions Planning Criteria Methods Detailed component design Materials Inlets and outlets Landscape Design Planning Processes Programming Method statements Construction Objectives Waste management Activities Frequencies Specifications Maintenance plans Maintenance

13 UK design resources: development integration

14 UK design resources: inspiration Page 14

15 UK: simple design tools for rapid planning Page 15

16 Detailed modelling tools for complex systems Model features: Soil, infiltration, evaporation Integration of 1D and 2D Time series rainfall Runoff volumes Infiltration volumes CSO performance analysis Flooding frequency analysis Depth Duration Courtesy Innovyze Page 16

17 What is needed for the future? Regulatory and government support for shift from seeing surface water as a problem to an opportunity Improved stakeholder engagement and partnerships (citizens as customers ) Stronger business case for investment Retrofit incentives for known flood risk areas Understanding of need for adaptability (pipes lack affordable flexibility) Education, awareness, removal of innovation barriers Page 17

18 What is needed for the future for criteria? Systems rather than component design approaches Efficient and cost-effective flood risk and pollution control (catchment specific? flow/volume control? design storms or time series rainfall?) e.g Uplifts of 40% for climate change increase present day 1:100 year return period to years In these conditions what difference does a development make on the receiving catchment? If it is small catchments which are most vulnerable focus on the receiving stream at the point of discharge? Sustainability criteria energy and material use Criteria that address the protection and preservation of water resources (including rainfall) Linking drainage with extreme event management Page 18

19 Long-term criteria To reduce the risks of short and long term performance deterioration: Construction management planning and inspection Maintenance: objective setting and management Asset data: collection and management Performance data: collection and management CAD & Design Updat e Capture LID Data GIS & Modelling Asset Maintenanc e Mapping Page 19

20 Thank You David Powers Page 20

21 Robust evidence to build on... Page 21