ASSUMPTIONS

ABOUT CLIMATE CHANGE

The study made predictions about sea-level rises and rainfall events in 2100 based on Government policy to plan for a possible sea level rise of 0.8 metres and on advice provided by Melbourne Water Water and State Government planning policy.

The assumptions used were that:

The sea-levels would rise 0.8 metres by 2100; and

Rainfall intensity would increase by 32 per cent by 2100.

ABOUT FLOOD EXTENT

Inundation levels for current and future average recurrence interval (ARI) events came from data supplied by Melbourne Water.

The study areas looked at were typically characterised by low-level flooding. This meant the height of floors within buildings was particularly pertinent when assessing the cost of damage. But, because the study only had floor-height information concerning the existing affected areas, assumptions had to be made about the floor-heights in future-affected areas. These assumptions were based on maximum and minimum Light Detection and Ranging (LIDAR) ground heights for each land parcel in the affected area.

Mapping of future inundation at four of the five case study areas did not include joint probability analysis for co-events such as a high-tide occurring with catchment flooding.

Predications of flooding in the case studies was averaged across the whole study area which may result in under or over-represented flooding in some areas.

ABOUT ECONOMIC COSTS

Damage was estimated only in relation to residential, commercial and public assets, clean-up costs and indirect costs for each case study. Indirect costs include disruption to business, transport and communications.

Losses due to flooded foreshore camping areas were estimated using average-spend-per-tourist advice supplied by Tourism Victoria.

ABOUT SOCIO-ECONOMIC CHANGES

Changes in land-use and population were factored into the analysis based on council plans and structure plans.