Flood Resilience Lab
Make it rain. Try not to flood the town. Change the storm, the catchment and the ground conditions, then compare what happens to runoff, river flow and flood risk.
Simplified teaching model. Rainfall, antecedent wetness, land cover and storage alter runoff, river response and flood risk. Designed for investigation, not real-world flood forecasting.
Set the storm.
Keep one variable changing at a time if you want a clean experiment. The model is simplified, but the relationships are real.
More intense rain can exceed infiltration capacity more quickly.
Longer storms add more water and give the catchment time to wet up.
A wet catchment has less spare storage before runoff begins.
Impermeable surfaces reduce infiltration and speed water toward the river.
Watch where the water goes.
Rainfall and river discharge through time.
The orange line is the bank-full threshold. When discharge rises above it, flooding begins in this simplified town reach.
Where did the rain go?
These three pathways add to 100% of the storm rainfall in this simplified model.
Run a storm to reveal the simplified rainfall split. Detention basins and reconnected floodplains act later by storing and delaying runoff that has already formed.
Read the catchment.
Run a storm to see how rainfall becomes runoff and river flow.
The model tracks a simplified balance between rainfall intensity, infiltration, surface runoff, catchment response time and channel capacity.
Can you reduce flood risk?
Run a baseline storm first. Then choose up to two measures and repeat exactly the same storm.
Did the catchment become more resilient?
Baseline storm
With resilience measures
A flood is a catchment response.
Rainfall does not automatically become river flow. Some water is intercepted, some infiltrates into the ground and some becomes surface runoff. The balance changes through a storm as the catchment gets wetter.
Urban surfaces usually reduce infiltration and connect rainfall to drains and channels more quickly. Vegetation, permeable ground and temporary storage can slow part of that transfer.
This is a simplified teaching model, not a flood forecast. Real floods also depend on catchment size and shape, geology, drainage networks, river geometry, tides, snowmelt, groundwater, storm movement and many other factors.
Can you make the catchment behave?
- 1. Same rain, different groundKeep the storm identical and compare dry soil with saturated soil.
- 2. Urban flashChange only land cover. Can you make the hydrograph peak earlier?
- 3. Build a floodFind the mildest storm that still exceeds channel capacity.
- 4. Protect the townChoose two resilience measures and reduce flood risk without changing the weather.