Maximum damage estimation

Maximum damage estimation#

A guide to estimate the maximum damage per square meter of different asset classes.

The calculations outlined in the following are implemented in the damage estimation spreadsheet template (LUISA_damage_info_curves*.xlsx) provided with CLIMAAX workflows that follow this methodology of estimating damages.

Note

The parameters in the formulas below correspond to columns C to AC in the spreadsheet template.

Asset classes#

Table 9 lists the asset classess distinguished in the damage estimation.

Table 9 Flood damage classes defined by Huizinga et al. (2017).#
Damage class	Description
Residential	Refers to residential buildings such as houses and apartments and their contents. Damage to assets in residential areas which are not residential buildings (i.e. in the public area and gardens) is not included
Commerce	Refers to commercial buildings and their contents such as offices, schools, hospitals, hotels, shops, etc. Damage to assets in commercial areas (i.e. in the public area and vehicles) is not included
Industry	Refers to industrial buildings and their contents such as warehouses, distribution centers, factories, laboratories, etc. Damage to assets in industrial areas (i.e. in the public area and vehicles) is not included
Transport	Transport facilities
Infrastructure	Roads and railroads
Agriculture	Based on damage resulting from flooded agricultural lands only (i.e. does not include farms, sheds, farming material, etc.)

Commercial, residential and industrial#

For building footprints#

The maximum damage that can occur to a building is a combination of construction costs and the value of the content inside a building. When a flood occurs, the building is damaged but also the furniture, machines, or store inventory is affected.

First, the construction cost is determined. When building costs are known in the region, this value can be filled in directly. Otherwise, the following relation found by Huizinga et al. (2017) can be used to calculate the construction cost for buildings per square meter:

(1)#\[\mathrm{construction\ cost / m^2} = a \cdot (\mathrm{GDP\ per\ capita})^b\]

Important

In the construction cost formula (1), values of the GDP and construction cost have specific units that cannot be changed. When using the $a$ and $b$ parameters of Huizinga et al. (2017; see below),

GDP must be specified in year 2010 US$ and
construction costs are computed in year 2010 €.

Suitable input values for GDP are provided by Huizinga et al. (2017) in the data spreadsheet attached to their report. The World Bank’s data portal can also be searched for GDP information.

Conversion of currency and adjustments for inflation should be applied to the output costs/damages, not the input GDP.

Based on the construction cost, the damage to existing structures is computed as

(2)#\[\begin{split}\begin{align} \mathrm{Max\ damage\ structure / m^2} = \; & \mathrm{construction\ cost / m^2} * \mathrm{depreciated\ value} \\ & * (1 - \mathrm{undamageable\ percentage}) * \mathrm{materials\ used\ factor} \\ \end{align}\end{split}\]

When the maximum damage for a structure is known, the damage to content can be estimated by multiplying the structure damage with a content importance factor $f$. It estimates how much the content is worth based on how valuable the building is.

(3)#\[\mathrm{Max\ damage\ content / m^2} = f \cdot \mathrm{Max\ damage\ structure / m^2}\]

The total damage per square meter can then be defined by adding the maximum content and structural damage together.

(4)#\[\mathrm{Total\ damage / m^2} = \mathrm{Max\ damage\ structure / m^2} + \mathrm{Max\ damage\ content / m^2}\]

Empirical values for building use classes

Huizinga et al. (2017) assume different building costs per type of building:

Asset class	a	b
Residential	24.078	0.3852
Commercial	33.642	0.3574
Industrial	30.824	0.3249

For a rasterized land use dataset#

To account for mixed use of land in a rasterized land use dataset like LUISA, we create land use class-specific parameters $a_\mathrm{landuse}$ and $b_\mathrm{landuse}$ by weighting the respective parameters of each asset class by the ratio of the class’ assets and all assets in the cell:

(5)#\[a_\mathrm{landuse} = R_\mathrm{res} \cdot a_\mathrm{res} + R_\mathrm{com} \cdot a_\mathrm{com} + R_\mathrm{ind} \cdot a_\mathrm{ind}\]

(6)#\[b_\mathrm{landuse} = R_\mathrm{res} \cdot b_\mathrm{res} + R_\mathrm{com} \cdot b_\mathrm{com} + R_\mathrm{ind} \cdot b_\mathrm{ind}\]

where

$R_\mathrm{res}$ is the ratio of residential assets in the specific land use cell,
$a_\mathrm{res}$ is the a variable for the residential-related assets,
$b_\mathrm{res}$ is the b variable for the residential-related assets,

and analogous definitions for $R_\mathrm{com}$, $a_\mathrm{com}$, $b_\mathrm{com}$ (commercial assets) and $R_\mathrm{ind}$, $a_\mathrm{ind}$, $b_\mathrm{ind}$ (industrial assets). A land use-specific importance of content factor $f_\mathrm{landuse}$ is defined in the same way:

(7)#\[f_\mathrm{landuse} = R_\mathrm{res} \cdot f_\mathrm{res} + R_\mathrm{com} \cdot f_\mathrm{com} + R_\mathrm{ind} \cdot f_\mathrm{ind}\]

When working with land use data that has a raster format, a single cell is not necessarily filled completely by building footprints. A density factor takes us from a fully build up land use cell to one which contains some ‘empty space’ between buildings:

(8)#\[(\mathrm{Total\ damage / m^2})_{landuse} = \mathrm{Total\ damage / m^2} * \frac{\mathrm{area\ covered\ by\ building\ footprint}}{\mathrm{total\ area}}\]

Agriculture#

Per land use type of agriculture, the value added can be changed to get some differentiation between the types of farming that is being done.

(9)#\[\mathrm{Value\ added / m^2} = \frac{\mathrm{Value\ added / hectare}}{10\,000}\]

Infrastructure and transport#

(10)#\[\mathrm{Damage / m^2} = \frac{\mathrm{Maximum\ damage}_\mathrm{average} * \mathrm{GDP}_\mathrm{country}}{\mathrm{GDP}_\mathrm{average}}\]

Note

Infrastructure and transport are not accounted for in the damage calculation spreadsheet template.

Material	Undamageable part
Concrete	0.4
Masonry	0.4
Wood	0
Mud	0.33
Informal/slum	0

Material	Materials used factor
Mud walls	0.2
Corrugate walls	0.6
Informal/slums	0.125
Rural	0.33

Maximum damage estimation

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