Lecture 8: Flooding

• River Floods (fluvial): occur when natural or artificial river banks are overtopped.
• What exacerbates floods?


  increasing urban areas, removing forests, land use change, changing rainfall pattern/intensity.
• Coastal Floods: occur when sea height surface is raised above normal level of wave and tide. regional land subsidence and and global sea level rise also contribute.
• Surface Water Floods (flash floods/pluvial): occur when heavy rainfall overwhelms the drainage capacity of the local area.
• Immediate Hazards: drowning, hit by objects, electrocution, hypothermia, mudflows and debris flows.
• Longer-term hazards: epidemic of waterborne diseases, chemical contamination of drinking water, damage to agricultural land and products.
• Land Use Planning: mapping of flood hazards. implement land use policies.
• Flood Risk Reduction Measures: reforestation/vegetation change. water retaining ecosystems (ponds/wetlands). managed retreat/realignment.
• Flood Diversion/Defence Measures: construct flood defences, enlarge channels or create overspill channels. construct storage reservoirs.
• Flood Resistant/Resilient Buildings: elevate living spaces, sealable doors.
• Forecasting and Warning: model flood behaviour and catchment characteristics. monitor storms and predict precipitation and floods. ISSUE FLOOD ALERTS AND WARNINGS.
• Education: how to respond, assemble emergency kit.