Thesis presentation for the development of a Real Time Flood Risk Forecasting Model

1. REAL TIME FLOOD
RISK
FORECASTING
N 8 5 9 4 6 9 4 B R E N D A N C O U LT E R
Development of a simplistic flood forecasting
model from freely available information

2. FLOODING
DESIGN RUNOFF LEVELS ARE
EXCEEDED
• Riverine: river overtopping their banks
• Flash flooding: exceeds stormwater drainage capacity
• Coastal: caused by storm surge
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3. PURPOSE OF RESEARCH
• Consequences – Economic, Environmental, and Loss of Life
• Provide early warning to reduce impacts
• Easily accessible to areas in need
• Extensive knowledge of hydrology not required
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4. OUTLINE
• Data acquisition
• Modelling programs and creation
• Risk analysis
• Future considerations
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5. DATA ACQUISITION
• Rainfall data
• Water flow
• Forecasted rainfall
• Catchment features
• Data analysis
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6. WATER DATA
• Historical and current rainfall data
• Source: Bureau of Meteorology
• Waterway depth and flow
• Source: Department of Natural
Resources and Mines
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7. FORECASTED RAINFALL
• Pivotal in flood risk forecasting
• Provided by Bureau of Meteorology as a graphic:
• Rainfall
• Chances of rainfall – minimum of certain
quantities
• Data needs to be processed before used in model
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8. TEMPORAL RAINFALL
DISTRIBUTION
• Forecast rainfall
• Total daily quantities
• Required to be analysed and processed
• Creation of temporal distribution
• Statistical analysis of past storm events
• Application for a time series
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9. TEMPORAL RAINFALL
DISTRIBUTION
• Forecast rainfall
• Total daily quantities
• Required to be analysed and processed
• Creation of temporal distribution
• Statistical analysis of past storm events
• Application for a time series
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10. RAINFALL PROBABILITY
• Bureau of Meteorology forecast rain:
• Rainfall quantities
• Minimum of 50% probability
• Anther simulation based on the same model parameters
required:
• Highly likely: 75 – 90% chance, smaller discharge and flood peaks
• Worst case scenario: 25% chance, significantly higher values
produced
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11. CATCHMENT FEATURES
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CURRENT WATERCOURSES
• Path water will take
VEGETATION AND IMPERVIOUS SURFACES
• Affects total runoff and runoff velocity
OBSTRUCTIONS
• Alteration to watercourses
STORAGES
• Features that retain water, such as depressions and dams

12. FLOOD MODELLING
RAINFALL RUNOFF:
• Converts rainfall into discharge after
losses
• Image displays the process
FLOOD ROUTING:
• Creates Hydrograph from upstream
conditions
• Popular methods include Muskingum
CONCEPTUAL:
• Artificial Neural Networks – Based off
neurons in the brain
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13. MODEL CREATION
MIKE URBAN:
• Chosen as flash flooding has higher consequences and more
difficult to predict
• Combines rainfall runoff and flood routing
THREE INPUT CATEGORIES:
• Drainage System Network
• Catchment and Sub-Catchment Data
• Boundary Conditions
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14. MODEL INPUTS
NETWORK
• Nodes (Manholes, basins, and outlets)
• Links (Pipes and channels)
CATCHMENTS
• Catchment area and drainage
• Also requires parameters such as ToC and Imperviousness
BOUNDARY CONDITIONS
• Rainfall time series input
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15. MODEL CALIBRATION
• Use “Trial and Error” method to calibrate parameters:
• Initial Loss (Less sensitive to small rainfall, reduces peaks)
• Reduction Factor (Reduces flood peaks)
• Time of Concentration (Changes shape of hydrograph)
• Time-Area Curve (Changes shape of hydrograph)
• Confirm with statistical parameters:
• Root Mean Square Error (RMSE)
• Coefficient of Determination (CD)
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16. TRUE DATA UPDATE
• Errors increase over time
• Initial Conditions and Catchment Parameters update:
• INITIAL CONDITIONS:
Apply most recent observed data and re-run model
• CATCHMENT PARAMETERS UPDATE:
Re-do calibration with newly recorded observational data
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17. MODEL OUTPUT
• Catchment Runoff Volume
• Water level in network
• Discharge throughout network
• Flow Velocities
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18. RISK ASSESSMENT
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LIKELIHOODSEVERITY
• Floodwater Depth (0-4)
• Water velocity (0-4)
• Location Importance (0-4)
• Models combined at beginning or after final assessment

19. RISK ASSESSMENT 2
• Examples of actions for different risk levels;
• Low risk: monitor situation
• Moderate: broadcast warnings
• High risk: Alert
• Extreme risk: broadcasting of top priority flood warnings
through all means necessary, mitigation of impacts of forecast
flood
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20. FLOOD WARNING BROADCAST
• Governed by “Australia’s Emergency Warnings
Arrangements”
• Responsibility on state and territory governments
• Delivery through
• Social Media
• News Sources
• Online
• Radio
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21. RECOMMENDATIONS
• Proof-of-Concept Model
• Adaption to worldwide scale (Picture of globe on right)
• Further analysis on temporal rainfall distribution
• Further research into downstream considerations
• Complete automation of the process
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22. CONCLUSIONS
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