“Gebruik van kansverwachtingen” - case studies - Jan Verkade en Karel Heynert 14 februari 2012

February 10, 2012 “Gebruik van kansverwachtinge” - casussen Waterschap Noorderzijlvest US National Weather Service, North Central River Forecasting Centre

Casus Noorderzijlvest najaar 2011

February 10, 2012 Water Board “Noorderzijlvest” Water Board: responsible for maintaining water levels in polder districts within acceptable levels (Fully controlled systems, well below MSL) 2010 event: flood warning called, but nothing happened Hydrologist was blamed Way forward: probability forecasts

February 10, 2012 Water Board “Noorderzijlvest” November 2011: forecasting – warning – response exercise Lessons: interpretation of probability forecasts not an issue information overload is decision makers: with these forecasts, I don’t have to make my own estimates of the inherent uncertainties probability forecasts used to devise scenarios (worst case)

US National Weather Service North Central region februari 2012

February 10, 2012 National Weather Service: North Central RFC Red River Grand Forks Fargo Mississippi River Minneapolis St Paul Missouri River Minnesota River

February 10, 2012 National Weather Service: North Central RFC Overstromingen relatief frequent (o.a. 2009, 2010, 2011) Naar aanleiding van gebeurtenissen van 1997: kansverwachtingen Op dit moment: middellange termijn (~90d) Nabije toekomst: korte termijn (tot 10 dagen vooruit)

February 10, 2012

Gebruikers van kansverwachtingen Emergency planners and emergency managers (State of Minnesota; gemeentes) US Army Corps of Engineers: “flood fighters” Reservoirbeheerders Energiebedrijven Media  iedereen maakt eigen afwegingen (!)  veel interactie tussen forecasters en gebruikers  in sommige gevallen interpretatie met hulp van consultants

February 10, 2012 Probability forecast study – purpose General move towards probabilistic forecasting, varying reasons To capture perceived benefits, simply having the probability forecast is not enough Additional effort may be required: visualisation communication decision-making verification “downstream” DSSs adaptation of business processes / procedures

February 10, 2012 Some conclusions Visualisation and communication Communiceren in termen van “gevolgen” (!) Iedere gebruiker heeft eigen wensen mbt visualisatie Reflection of physical processes Niet alleen belangrijk voor interpretatie van verwachtingen Maar ook voor acceptatie Decision making Training and education Use of and rationale for probability forecasting

February 10, 2012 Some conclusions : decision-making Decisions are made based on a consequence, not on a hazard Must transform probabilities to make a binary decision >Often times: intuition only Decision criteria can now include explicit expression of risk Risk = Probability x Consequence NWS concentrates on forecasting a possible hazard; decision support is needed to translate this into meaningful consequences

February 10, 2012 Some conclusions: training and education Information overload is a real issue Trying to understand the forecast is not conducive to good decision making This should then be done prior to a “crisis situation” Links between “hydrological variables” and real issues not always clear for non-experts Everyone found the NWS webinars extremely useful Need to explain how to access the information in the forecasts by fixing a dimension.

February 10, 2012 Some conclusions: why probabilities Rationale for moving towards probability forecasting: “More realistic forecasts” widely accepted >Deterministic forecasts are “over confident” “Risk based” decision making easier said than done >Support systems not generally in place Benefits may not reside with both forecaster and end user >Forecasters provide more complete information >Users must do more interpretation and post-processing

February 10, 2012

2,5% kans op overschrijding

February 10, 2012 Casus Maas? Discussie… 1.Wat zijn de huidige procedures? 2.Hoe ga je nu om met onzekerheden? 3.Waar zie je eventuele meerwaarde van marges of kansverwachtingen? 4.Ga je andere beslissingen nemen indien je de beschikking hebt over marges of kansverwachtingen?