*3.3. Selection of Metrics for Hazards Characterization and Mapping*

Depending on the available information and model used, different criteria are applicable, resulting in a more comprehensive understanding of the hazards. The urban functions selected to illustrate the application of this methodology are those related to urban mobility and wastes collection.

In Table 3, a summary of metrics selected for flood related hazards for different approaches and scenarios is given.


**Table 3.** Definition of flood related hazards for different approaches and scenarios.

For the current situation, the historical data on flood events allowed obtaining hazard maps with areas as a function of flooding frequency, used to cross-validate the results from the simulations. A systematic recording of water levels was not undertaken and information on the water levels reached in each flood event is not available. For surface flows, the water level metric allowed for evaluation of consequences in properties.

#### *3.4. Selection of Representative Scenarios*

The selection of representative scenarios took two aspects into account: the infrastructure and climate. For the former, two situations were analysed: existing infrastructure and adaptation strategies (CAS, or climate adaptation strategy). For the latter, two situations were studied: the current situation and a future situation where climate change is accounted for. From the results of available studies on climate change to Lisbon, to characterize current situation and climate change [34,35], representative scenarios were selected, for both the current situation and future situation, for rainfall and for Tagus river estuary levels. These scenarios are aligned with those used by the Municipality for climate adaptation planning purposes.

For both climate situations, three return periods were selected (10 years, 20 years and 100 years) to take into account the variations in precipitation intensity. The actual values for existing infrastructure with climate change were defined as relative changes to current situation values. To limit the number of hydraulic simulations, an average estuary water level was adopted for each climate situation. The reference period for the future situation taking climate change into account is 2071-2100 (worst-case scenario).

Three scenarios were analysed and compared: CS, used as the baseline, with the current system and climate characteristics; BAU, business as usual (for the system) assuming a future situation with climate change; and CAS, a future situation including the implementation of selected strategies for climate adaptation and assuming climate change scenarios.
