Interactive flood risk assessment tool for rivers

How to Use This Tool

This interactive flood risk assessment tool uses the Global Flood Awareness System (GloFAS v4) to analyze river discharge and flood risk at any location worldwide.

Getting Started:

1. Click any point on the map to analyze that location
2. Wait for the data to load (indicated by the loading spinner)
3. View the discharge data in the chart and risk assessment in the panel
4. Adjust the forecast period or historical comparison as needed

Understanding the Results:

The tool provides several key measurements:

• River Discharge: Measured in cubic meters per second (m³/s), showing water flow volume
• Risk Levels:
• Low Risk (< 100 m³/s): Normal river conditions
• Medium Risk (100-500 m³/s): Elevated water levels, monitor situation
• High Risk (> 500 m³/s): Potential flooding conditions

Data Visualization:

• The line chart shows river discharge over time
• Blue shading indicates forecast uncertainty
• Historical data helps compare current conditions with past patterns
• Statistics panel shows key metrics including average, maximum, and minimum discharge rates

Technical Information

Model Specifications:

• Uses GloFAS (Global Flood Awareness System) Version 4
• Spatial resolution: 0.05° (approximately 5 km)
• Temporal coverage: 1984 to present
• Forecast range: Up to 7 months ahead
• Daily data updates

Limitations and Considerations

Important Limitations:

1. Spatial Resolution:

• The model uses a 5km grid, meaning small streams or local flooding may not be captured
• Results represent the largest river within the selected grid cell
• Urban flooding and flash floods are not included in this model

1. Temporal Limitations:

• Forecasts become less certain further into the future
• Historical data may not capture recent changes in river systems
• Daily averages may not capture rapid flood events

1. Model Constraints:

• Does not account for local flood defenses or infrastructure
• May not accurately represent modified river systems (dams, diversions)
• Urban drainage systems are not included in the model

1. Local Factors Not Considered:

• Local rainfall intensity
• Ground saturation levels
• Snow melt conditions
• Coastal flooding or tidal effects
• Urban development changes

Best Practices for Use

Recommended Usage:

1. Use as a screening tool for general flood risk assessment
2. Compare multiple time periods to understand patterns
3. Consider local knowledge and conditions
4. Verify results against other data sources

Not Recommended For:

• Emergency response decisions without local verification
• Insurance or legal purposes without additional analysis
• Detailed urban flood analysis
• Small stream or flash flood prediction

Data Sources and Updates

• Data provided by the Global Flood Awareness System (GloFAS)
• Part of the Copernicus Emergency Management Service
• Daily updates for forecasts
• Historical data from 1984 onwards

Additional Resources

For more detailed flood risk assessment, consider:

• Local flood management authorities
• National weather services
• Regional water management agencies
• Local historical flood records

Disclaimer

This tool provides general guidance and should not be used as the sole basis for critical decisions. Always consult local authorities and professional flood risk assessors for specific situations.

I’ll expand on the technical details of the model and provide concrete example scenarios.

Technical Model Details

GloFAS v4 (Global Flood Awareness System) Technical Specifications

Model Architecture:

• Coupling of HTESSEL land surface model
• LISFLOOD hydrological and channel routing model
• ERA5 meteorological reanalysis data integration
• 0.05° x 0.05° (~5km) spatial resolution grid

Computation Components:

• Surface runoff generation
• Soil moisture dynamics
• Groundwater processes
• River channel routing
• Lake and reservoir simulation
• Floodplain inundation

Input Data Sources:

• Precipitation data from ERA5
• Temperature and evaporation data
• Land use and soil type information
• River network morphology
• Digital elevation models

Output Parameters:

• River discharge (m³/s)
• Return period levels
• Anomaly detection
• Probabilistic forecasts
• Historical comparisons

Example Interpretation Scenarios

Scenario 1: Urban River System

Location: Major city river
Readings:
- Current discharge: 450 m³/s
- Historical average: 200 m³/s
- Forecast trend: Increasing

Interpretation:

• Risk Level: Medium-High
• The discharge is 225% of normal
• Potential for riverside flooding
• Monitor upstream conditions
• Check local flood defenses

Recommended Actions:

• Monitor weather forecasts
• Check flood defense status
• Review emergency plans
• Monitor upstream gauges

Scenario 2: Agricultural Region

Location: Agricultural floodplain
Readings:
- Current discharge: 80 m³/s
- Historical average: 75 m³/s
- Forecast trend: Stable

Interpretation:

• Risk Level: Low
• Normal seasonal conditions
• Suitable for regular operations
• No immediate concerns

Recommended Actions:

• Continue normal monitoring
• Plan regular activities
• Document baseline conditions

Scenario 3: Mountain Valley

Location: Mountain river system
Readings:
- Current discharge: 600 m³/s
- Historical average: 150 m³/s
- Forecast trend: Rapidly increasing

Interpretation:

• Risk Level: High
• 400% above normal flow
• Potential flash flood conditions
• Rapid response needed
• High erosion risk

Recommended Actions:

• Immediate alert to authorities
• Monitor upstream conditions
• Prepare for evacuation
• Check infrastructure integrity

Scenario 4: Seasonal River

Location: Seasonal river basin
Readings:
- Current discharge: 25 m³/s
- Historical average: 200 m³/s
- Forecast trend: Below normal

Interpretation:

• Risk Level: Low (but drought concern)
• 87.5% below normal flow
• Potential water shortage
• Ecosystem stress likely

Recommended Actions:

• Water conservation planning
• Monitor groundwater levels
• Assess ecological impacts
• Review water allocation

Understanding Return Periods

The tool uses return periods to contextualize flood risk:

2-year return period

• Common high water events
• Usually contained within banks
• Regular seasonal high flows

5-year return period

• Minor flood conditions
• Some floodplain inundation
• Agricultural impacts possible

20-year return period

• Major flood conditions
• Significant inundation likely
• Infrastructure at risk

100-year return period

• Extreme flood conditions
• Extensive flooding likely
• Critical situation

Interpreting Forecast Uncertainty

The tool’s forecasts include uncertainty ranges:

Short-term (1-7 days)

• Highest confidence
• Narrow uncertainty range
• Direct operational use

Medium-term (8-30 days)

• Moderate confidence
• Wider uncertainty range
• Strategic planning use

Long-term (1-7 months)

• Lower confidence
• Broad uncertainty range
• Seasonal planning only