CIP session 6: Flood Risk Analysis and Management

Question 1

Adaptation options that would be suitable to reduce flood risk. This could either be an adaptation option that reduces the direct damages, or an adaptation option that could reduce the indirect effects

Answer 1

• Dry-proofing: the practice of making a building watertight or substantially impermeable to floodwaters up to the expected flood water height.
• Wet-proofing reduces damage from flooding in three ways: allowing flood water to easily enter and exit a structure in order to minimize structural damage; Use of flood damage resistant materials; and elevating important utilities.
• Land-use zoning, such as avoiding future construction in potentially flooded areas and planning of urban development in low hazard areas.
• Inventory management (i.e. make sure that business can continue as usual in the direct post-disaster aftermath due to availability of stock)

Question 2

3 main flood types

Answer 2

• Pluvial: Cloudburst with large amounts of rain in a short period of time. Drains cannot handle this. Most often in summer (in Europe). In the tropics: during or after the monsoon.
• Fluvial: To much water upstream. Can last very long (> multiple weeks). Can happen throughout the year (but mainly spring and winter)
• Coastal: Rising sea, tides, short, together with intense storm.

Question 3

direct and tangible impacts flood damages

Answer 3

Residences, Business interruption, vehicles, Roads, Agricultural land and cattle

Question 4

direct and intangible impacts flood damages

Answer 4

fatalities, injuries, utilities and communication, historical environmental and cultural losses

Question 5

indirect tangible impacts flood damages

Answer 5

Damage for companies outside flooded area, adjustments in production and consumption patterns outside flooded area. Temporary housing of avecuees.

Question 6

indirect intangible impacts flood damages

Answer 6

societal disruption, psychological trauma, undermined trust in authorities

Question 7

4 Flood maps for Flood Hazard & what determines them? (in hindsight not really sure how I meant this question)

Answer 7

• Historical Flood map, Flood Extent map. Flood Depth map, Flood Danger map.
• Determined by discharge, probability, water depth, inundation depth

Question 8

Difference resilience and vulnerability

Answer 8

Resililance is more about the ability to bounce back

Question 9

Synthetic vs. Empirical Flood Models

Answer 9

• Emprical has greater accuracy, but often details not present.
• Synthetic has a higher level of comparability but what-if scenarios are subjective.

Question 10

Relative vs. Absolute damage function.

Answer 10

Relative is more simple but estimation of values of the objects assets might bring in uncertainty.
Absolute does not need asset value , but need regular de-calibration.
Have to specifiy if you use replacement (=2 times higher) or depreciation values.

Question 11

Object vs. Raster based approach

Answer 11

Object can differentiate between buildings, raster for larger areas.

Question 12

why is EAD (= expected annual damages) useful?

Answer 12

▪ Objective measure of risk
▪ Quantified
▪ Monetized
▪ Difference in risk is benefit or cost

Question 13

Reducing risks methods

Answer 13

• Prevention: lowering frequency/magnitude of flood (dikes, room for river, compartementalization)
• Mitigation: reduce losses (wet and dry proofing)
• Preperation (forecasting, rules and regulations, public awareness)

Question 14

Cost Benefit Analysis defenition

Answer 14

A framework which supports transparent, coherent, and systematic decision-making based upon a common, monetized yardstick that can be used to evaluate various risk reduction strategies. Discount benefits need to outweigh discount costs.

Question 15

3 different types of uncertainty

Answer 15

• Aleotoric: intrinsic randomness (e.g. flipping a coin). Cannot be reduced with more data, needs to be quantified.
• Ontological = you don’t know what you don’t know
• Epistemic = not yet fully understood, lack of knowledge. Reduced with more data / knowledge

Question 16

key uncertainties in within direct damage modelling assesment.

Answer 16

The uncertainty is in:
Object data
▪ Quantity & location (epistemic, we don’t know exactly where everything is)
Maximum damage
▪ Object value (aleatoric, variability in the housing market)
▪ Susceptibility to hazard (epistemic, we don’t have very good depth-damage curves due to a lack of knowledge/data) (also aleatoric, there is some randomness in the unique way in which a house is hit by a hazard)
Damage function
▪ Parameter representation (epistemic / aleatoric)
▪ Knowledge/data about damage (epistemic)