II. Climate change and urban waters

Question 1

Some projections for mid-latitude cities
More intense rainstorms (3)

Answer 1

• Increased occurrence of urban flash floods
• More stormwater overflow events into urban rivers
• More infiltration towards groundwater

Question 2

Some projections for mid-latitude cities
Longer drought periods (2)

Answer 2

• Reduced water availability for drinking water supply and plants
• Warmer drinking water (in pipes) has higher risk of germination

Question 3

Some projections for mid-latitude cities
Higher temperature, longer heat periods (2)

Answer 3

• Amplification of urban heat island effect
• Detrimentalimpacton flora, fauna, people

Question 4

Def. Urban flash floods

Answer 4

• caused by heavy or excessive rainfall in a short period of time (less than 6 hours)
• accompanied by a complete failing of the urban drainage system
• can occur within minutes or a few hours

Question 5

Urban flash floods
Global trends -observations

Answer 5

general increase of short extreme storm events over the last 20-70 years
(observed sub-daily rainstorm data)

Question 6

Urban flash floods
Damages (4)

Answer 6

• Household damages (possibly insured), car damage
• Damageon infrastructur (streets, tunnels, underground railways, underground parking, cables) -> often very large damage
• Health risk, bad small, rats…
• Large inflow of contaminants into urban surface waters

Question 7

Urban flash floods
Research frontier (4)

Answer 7

• Past, current and future trends of rainstorm characteristics (data availability in Germany, Europe, World)
• Real-time warning for urban flash floods
• Diffuse pollution dynamics of urban flash floods
• Alternatives to conventional drainage: green infrastructure, semi-natural rainwater management