The Government this week released its Surface Water Action Plan, aiming to tackle surface water flooding which affects up to 3.2 million properties in England. It seeks to bring our preparedness more closely into line with that from main rivers and the sea. We review the key points.
The Environment Agency (EA) has improved its surface water flood risk mapping but this latest plan recognises that it is still less robust than flood risks from rivers and the sea.
It identifies that mapping is limited by not accurately capturing:
The EA is charged with improving national surface water mapping and risk assessments. This will be achieved through improved modelling approaches, better quality data and combining the effects of flooding from different sources. The first improved maps will be available by the end of winter 2020/2021.
We look forward to working with the EA on refining surface water risk assessment including the role that groundwater plays in surface flood modelling.
Our GW5 national groundwater flood risk map delivers more granular data showing areas where surface water flood risk may be elevated by a high groundwater table at the property level.
LLFAs have the leadership role on surface water management. Water and sewerage companies also have an important role to play, as they are responsible for much of the drainage network. Securing the long-term resilience of wastewater systems and providing for resilience against flooding and wider risk is a key priority.
Ofwat requires water and sewerage companies to meet the following performance commitments:
Groundwater infiltration to sewers reduces their capacity to cope with surface water flooding. The role of groundwater is a key element to understanding surface water risk for sewer flooding.
We are engaging with water companies to integrate our infiltration and groundwater data as part of their asset management and resilience plans.
Surface water flooding is more difficult to forecast than flooding from rivers and the sea. Current meteorological methods cannot determine where this heavy rain will fall with the necessary levels of precision, and within a useful forecast lead time. The Met Office has launched an early warning for thunderstorms this summer as a trial. They, the EA and the Flood Forecasting Centre (FFC) are carrying out a review of how improvements can be made in surface water flood forecasting and communication.
We work closely with the FFC. Our real time groundwater flood risk and sewer infiltration forecasting is ensuring sufficient advance notice to utility companies, local communities and emergency responders to put contingency plans into operation.
3 levels of management plans are now required to mitigate surface water flooding:
The 25 Year Environment Plan also includes specific commitments to strengthen surface water provisions, including putting in place Sustainable Drainage Systems (SuDS).
The Surface Water Management Plan commits to amending the National Planning Policy Framework (NPPF), Planning Practice Guidance and Building Regulations to encourage the uptake and long term maintenance of SuDS.
Draft revisions to the NPPF include a proposed requirement for all major development and all development in flood risk areas to contain SuDS unless there are clear reasons they would be unsuitable.
LPAs should also ensure maintenance arrangements of SuDS are in place over the lifetime of the development. The final revised NPPF is due to be published later this summer.
There are clear management obligations across local government, national agency and utility companies to plan for these random, unpredictable surface flooding events. This extends to future new build development to ensure they do not exacerbate surface water flood risk.
A greater role for fully comprehensive Flood Risk Assessments and better data ensures that GeoSmart’s data and desktop reports will be at the heart of planning submissions and resilience planning in the future.
For more information, contact us on 01743 581 415 or email firstname.lastname@example.org
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