Michael Cranston Flood Forecasting and Warning Manager SIPR Event, Dundee, 21 st June 2011

© Crown copyright Forecasting and Warning – meeting the needs of partners How do emergency plans best adapt to new advance forecasting…

© Crown copyright Aims Review the developments in flood forecasting and warning Consider the challenges for The science Communication of flooding risk

© Crown copyright Part 1: Review the Developments in Flood Forecasting and Warning

© Crown copyright Developments in Flood Forecasting and Warning “…public expectations around flood warning systems can never be fully met.” Association of Chief Police Officers of Scotland. Scottish Parliament (2008) Flooding and Flood Management Review, RAE Committee 2 nd Report

© Crown copyright Recommendations for Flood Warning National flood warning strategy and further expansion including coastal areas Direct dissemination of warnings Pluvial flood warnings Developing the science to improve flood warnings Understanding the risk – critical infrastructure Improving public access and understanding

© Crown copyright Direct Dissemination of Warnings New direct warning service through Floodline Launched March flood warning areas Now has over 10,000 customers 20% of those targeted to receive warnings

© Crown copyright Direct Dissemination of Warnings

© Crown copyright Developing the Science “…Evidence suggests that increased lead times for predicting events are directly related to reductions in the damage caused to properties and infrastructure.” Pitt (2008) Lessons learned from the 2007 summer floods.

© Crown copyright Developing the Science

© Crown copyright Developing the Science Development of SEPA’s flood forecasting capabilities Launch of FEWS Scotland in 2007 State of the art flood forecasting technology Incorporating hydrology and meteorology data to provide flood forecasts for selected catchments Data and forecasting openly shared with responders

© Crown copyright Developing the Science “…The regular updates received from SEPA – re. the river levels and the Met Office – re. the weather forecast helped to determine decisions regarding the allocating of resources by all services involved..” East Ayrshire Council

© Crown copyright Hydrological and Meteorological Collaboration “…the committee recommends that the Scottish Government ensures that SEPA has the necessary funding to enable it to collaborate with the Met Office to provide an effective flood warning system for all types of flooding.” Scottish Parliament (2008) Flooding and Flood Management Review, RAE Committee 2 nd Report

© Crown copyright Service Aims Provide a joint hydrological and meteorological forecasting service to promote flood vigilance 5 days ahead Provide a joint service to provide surface water/flash flooding alert service in the future Provide better forecasting support service to SEPA’s regional flood warning teams

© Crown copyright SEPA Area Flood Warning Teams: Flood Detection (local) Flood Forecasting (local) Flood Warning Real time data FEWS Met Office Services to Government: Forecasts Heavy Rainfall Warnings Radar/forecast output Public Weather Service: Forecasts NSWWS PWS Advisors CCA Responders – Flood Response Flood Forecasting Centre NSWWS: Alert Warning Flood Warning Forecasts and Alerts under contract Flood Forecasting Service Flood Vigilance Flood Forecasting (strategic) Flood Detection (strategic) Flood Advice R&D UKCMF R&D Consistency of products X-border coordination Flood Guidance

© Crown copyright Highlights Providing a new flood guidance product to 150+ customers in Scotland Improved countrywide communication on flood risk More targeted meteorological guidance and forecast for flood warning Improved flood awareness and vigilance, particularly for new customers

© Crown copyright Part 2: The Challenges Ahead

© Crown copyright Surface Water Flood Risk “…the committee is particularly struck by the absence of any pluvial warning system…(but) does not underestimate the technical and practical challenges...” Scottish Parliament (2008) Flooding and Flood Management Review, RAE Committee 2 nd Report

© Crown copyright Challenges Ahead Developing our forecasting capabilities and science Communication of flood risk

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Building our forecasting expertise Partial coverage of hydrological modelling capabilities Challenges in observations and forecast of rainfall Combined implications for providing countrywide flood forecasts Rapid response catchments and surface water flooding

© Crown copyright Grid to Grid Countrywide Forecasts CEH Wallingford (2009) Provisional application of the G2G Model to the Irvine events of October CEH Wallingford, Wallingford, Oxon., 8pp.

© Crown copyright The value of nowcasts in hydrological forecasting “…it is demonstrated that the rainfall predictions provided by Nimrod (UKPP) are uncertain and at times biased, it is also shown that there is considerable benefit in their use for flood forecasting when compared to the alternative of using no future prediction of rainfall.” Werner and Cranston (2009) Understanding the value of radar rainfall nowcasts in flood forecasting and warning in flashy catchments. Meteorol. Appl., 16,

© Crown copyright Semi-permanent bands of rain in SE flow (believed to be ‘orographic correction’), Good example along Great Glen (this can bleed through to ‘nowcast’ and associated products) and lead to unrealistic accumulations.

© Crown copyright Managing uncertainty and error

© Crown copyright Uncertainty in Forecasts How are the errors in radar measurement propagated into rainfall forecasts What more can hydrologists do to manage this uncertainty What additional challenges are there to going beyond 6 hours in flood forecasting

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STEPS Nowcasts (T+6) - Locally intense rainfall over the 6 hour model period - Confirmed previous 36 and 24 hour predictions - Over 100 mm recorded in Tyndrum

© Crown copyright Deterministic UK4 Model - 24 hour forecast accumulation up to 1800 on Wed 6 th April Forecast for approx 24 hours of rain, often heavy with significant accumulations. - > 100 forecast

© Crown copyright MOGREPS-R - Well defined area of >50MM in 24 HR up to 1800 on 6th April. Probability high and fits with area of high risk and deterministic forecasts hence reasonably high confidence.

© Crown copyright Uncertainty in Forecasts Raingauge Radar T0 Automatic Input to Hydrological Model STEPS T+6 UK4 T+36 MOGREPS-R T+54 >

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Challenges in communicating uncertainty “…if someone had told us that these estimates (flood forecasts) were not an exact science, or that other countries predict potential river crest heights in probabilities for various levels, we may have been better prepared.” Glassheim (1997) Fear and loathing in North Dakota. Natural Hazards Observer, XXI, 1-4.

© Crown copyright Challenges in communicating uncertainty Need to clear understanding across all organisations on the risk matrix

© Crown copyright Consistency in Guidance FLOOD RISK MATRIX GUIDANCE Very LowLowMediumHigh Typical ImpactsMinimal Disruption Generally no impact, however there may be:  Isolated and minor flooding of low-lying land and roads  Isolated instances of spray/wave overtopping in coastal roads and promenades Minor Disruption  Localised flooding of land and roads – risk of aquaplaning  Localised flooding affecting individual properties  Localised disruption to key sites on floodplains  Individual properties in coastal locations affected by spray and/or wave overtopping  Local disruption to travel Moderate Disruption  Flooding affecting parts of communities  Damage of buildings/structures is possible  Possible danger to life due to fast flowing/deep water/ wave overtopping/ wave inundation  Disruption to infrastructure Significant Disruption  Widespread flooding affecting whole communities  Collapse of buildings/structures is possible  Danger to life due to fast flowing/ deep water/ wave overtopping/ wave inundation  Widespread disruption or loss of infrastructure  Large scale evacuation of properties may be required Expected Partner Response Level Business as usualSingle agency operational response. Multi-agency response likely to be needed Predominantly at tactical level. SGoRR may be considered Multi-agency strategic response likely at SCG level or regional level. Mutual aid likely with perhaps national co- ordination. SGoRR convened. Implications for public Generally no impact; however there may be some isolated and minor flooding. Little or no disruption to travel although wet road surfaces could lead to difficult driving conditions. Localised flooding possible. Wet road surfaces and possibility of ponding water, especially in known trouble spots. Local disruption to travel – longer journey times. Flooding of land and roads and property is likely. Disruption to travel and infrastructure Widespread flooding of property. Severe disruption to travel. Loss of gas, electricity, water supplies. Significant disruption to communities. Guidance on likelihood Confidence is very low. Forecast suggests less than 20% chance of occurrence. Confidence is very low. Forecast suggests between 20% and 40% chance of occurrence. Confidence is medium. Forecast suggests between 40% and 60% chance of occurrence. Confidence is medium. Forecast suggests greater than 60% chance of occurrence.

© Crown copyright Challenges Ahead Development of countrywide flood forecasting system – forecasts ‘everywhere’ out to 5 days Needs very close meteorology and hydrology working to understand the uncertainties and predict shorter lead time flooding Need for clear communication of flood risk for all sources of flooding

© Crown copyright Conclusions Significant effort into developing forecasting and warning Combined hydrological and meteorological understanding of the flood risk from all sources …but not without considerable challenges

© Crown copyright Forecast 21 st June 2011 There is a low risk of flooding in eastern Scotland through today and into Wednesday which may lead to minor disruption. For the remainder of the forecast period and areas, flooding risk is very low. Flood Guidance Statement (21 st June 2011) Scottish Flood Forecasting Service

© Crown copyright Forecast 21 st June 2011

© Crown copyright Forecast 21 st June 2011

© Crown copyright Forecast 21 st June 2011

© Crown copyright Forecast 21 st June 2011