Settings

The Settings tab enables you to configure your analyses. It provides options to:

• Include various additional damages in your damage totals, e.g. vehicle damages or impacts on mental health.

• Set thresholds to be considered by the analysis, e.g. offset from DEM to floor levels.

• Configure economic assessments, e.g. specify discount rates and write-off.

Settings can be used just in the current Damage Calculator session or saved as defaults to then be automatically applied in future sessions.

In addition to the Settings tab, other tabs in Damage Calculator enable you to define input data and associated metadata to be utilised in the current analysis:

• Calculation Information tab - specify flood depth data, property data and required economic analyses.

• Depth/Damage Curves tab - review depth/damage relationships for different property types as defined in the depth/damage curve dataset (specified on the Settings tab)

• Property Level Protection - review impacts of different property level protection options as defined in the depth/damage curve dataset (specified on the Settings tab)

This section details the settings and input data required to define your Damage Calculator analysis.

Property Data Input in .csv or .shp format

Property Data may be in .csv or .shp format. 

Flood Data Source

Damage calculator provides two options for input of flood depth / level data.  This can be input either via hydraulic model results (as water depth or water level grids), or via columns in the property dataset.  The technical requirements of both methods are described in Flood Data.

Categorising results by geographical area / other criteria

It is often useful to break down damage calculator results into categories, either as geographical areas, or using other criteria.  

A ‘studyArea’ column in field mapping allows this.  If a ‘studyArea’ column is populated within the property dataset, damage calculator will sort damage results into the specified areas and output the totals in the ‘(projectName)_summary.csv’ output.  An illustration of this is provided in the figure below:

Appraisal Period

The Appraisal Period box on the ‘Calculation Information’ tab should be set to the required appraisal period.  This does not have to be equal to the number of years between the first and last specified scenarios.  

•    If the appraisal period is set to a shorter period than the time between the first and last scenarios, damage calculator will ignore later scenarios.  

•    If the appraisal period is set to a longer period than the time between the first and last scenarios, damage calculator will extrapolate beyond the final scenario.  It should be noted that the type of extrapolation undertaken will depend on the interpolation method selected – this is detailed in Theory of Annual Average Damages (ADD).

Capping and Writeoff

PVD calculations can be undertaken applying capping to market value, writeoff or both.  The calculation methods applied and the additional data requirements for these are described in this section. 

Additional Data Requirements

Market values for properties must be set up in the property dataset for capping and writeoff calculations to be undertaken.  This is done by adding an extra field to the property dataset (csv text file or shapefile) entitled “MarkVal” and populated with numerical market values.  If working in England, market values may be obtained from the FHRC MCM.  

Capping

If the ‘apply capping’ box is ticked, damage calculator will determine the year in which direct property PVD damage equals or exceeds the specified market value.  After this point, the property is considered ‘capped’, and no further direct damages are calculated.  Furthermore, no additional damages related to property flooding are calculated. 

Writeoff

If the ‘apply write off’ box is ticked, damage calculator will compare the onset of flooding for that property with the specified writeoff %AEP for each scenario / epoch.  If a property floods more frequently than this, it is considered ‘written off’ in the year where this occurs.  After this point, no further direct damages are calculated.  The market value of the property is discounted in the year of writeoff, and the discounted market value added to the total damages.  Furthermore, no additional damages related to property flooding are calculated.  It should be noted that writeoff is calculated for upper floor properties, to represent the fact that if the ground floor of a property is written off, the upper floor is also likely to be uninhabitable.  If this is not required, the property should be deleted from the property dataset.

Both Capping and Writeoff

If a property is subject to both capping and writeoff, damage calculator will check for which occurs earliest, and apply that.  If a property is both capped and written are applied, total direct property damages (consisting of the sum of direct flood damages plus the discounted market value in the year of writeoff) may still not exceed the market value, and will therefore be capped to the market value. 

Depth Damage Curves

Depth Damage curves can be selected from the ‘Depth/Damage Curves’ tab of the interface.  Curves can be selected from the two dropdown menus (for residential and non-residential properties) at the top of the tab.  Options are available for various attributes of flooding, including:

•    Flood duration – curves are available for a range of flood durations 

•    Flood warning - curves are available for ‘no flood warning’ and a range of flood warning lead times

•    Flood water type – curves are available for a range of water types including storm water, saline (salt) water, sewage and contaminated water. 

•    With / without cellars – damages can vary if cellars are considered for certain property types

The selected curve sets are listed in the left-hand panel in a tree view.  The underlying depth/damage data associated with the selected (highlighted) row is plotted on the adjacent chart and listed in the adjacent table.

Run flood depth sensitivity tests

Building thresholds are often a source of uncertainty within damage calculations.  Damage calculator provides two options to help quantify this uncertainty.  These are:

•    A ‘Preset Standard Value’ option, which applies the same threshold uncertainty values to all buildings. 

•    A ‘Values from Property File’ option.  This allows different threshold uncertainty values to be applied to all buildings. 

Preset Standard Value

This option applies a global standard uncertainty value to all building thresholds.  For example, if a value of 0.1 is input, then three damage analyses will be run.  Firstly a standard analysis will be run in which thresholds as input either in a threshold column or as an offset from DEM to floor are used.  Secondly, a sensitivity analysis will be run in which all thresholds are lowered by 0.1m, effectively making flooding 0.1m deeper at all properties.  Thirdly, a sensitivity analysis will be run in which all thresholds are raised by 0.1m, effectively making flooding 0.1m shallower at all properties. 

Values from Property File

This option applies different uncertainty values to each building threshold.  For this analysis to be run, two additional thresholds are required in damage calculator field mapping – a ‘th_lower’ column, and a ‘th_upper’ column, representing lower and higher threshold estimates than the central estimates.  The values input to these columns may be estimated by the user, or quantified using GIS analysis of the DEM used to run the hydraulic model. If this option is selected, three damage analyses will be run. Firstly a standard analysis will be run in which thresholds as input either in a threshold column or as an offset from DEM to floor are used.  Secondly, an analysis will be run using thresholds from the ‘th_lower’ column.  Thirdly, an analysis will be run using thresholds from the ‘th_upper’ column.

Include cellar values in calculation

Non-residential property types within the MCM datasets (provided by FHRC) are each supplied with two sets of damage curves; one with cellar damages and one without.  Ticking the box instructs damage calculator to use ‘with cellar’ curves.  

Calculate damages for upper floor levels

• This setting (on the Settings tab) is a checkbox, which is unticked by default.

• For Damage Calculator to be able to interpret floor level, the ‘floorlevel’ column in the property dataset must be populated as described in XXXXX. 

• Assuming that the floorlevel column has been populated:

  • If the checkbox is ticked then Damage Calculator will use the property code in the specified property dataset to calculate direct property damages.  

  • If the checkbox is NOT ticked then no direct damages will be calculated for the property. 

• If a floorlevel column is not populated, then direct property damages will be calculated for all properties.   

Interpret residential property sub-type codes

The following section applies largely to work undertaken in England using the Environment Agency’s National Receptor Dataset (nrd) and the FHRC MCM. 

The FHRC MCM defines several types of residential property via the mcmcode attribute.  For example, ‘11’ represents a detached house, ‘12’ represents a semi-detached house, etc.  The MCM provides depth damage curves for each of these residential property types. 

However, the NRD only contains a single mcmcode ‘1’, which represents all residential properties.  Use of this average code in damage analysis results in less detailed, less accurate results than would be obtained using the ‘11’, ‘12’, etc codes described above.  However, the NRD does contain information in other columns which can be used to define a more detailed property code. 

The ‘interpret residential property sub-type codes’ checkbox can be ticked to instruct Damage Calculator to look for this information in the property dataset attributes table, allowing damage calculator to use a  more precise MCMcode (and hence depth damage curve) for each property analysed.

Damage calculator is capable of interpreting data from both nrd2014 and nrd2021.  What it does is each case is detailed in the following section:

nrd2014

nrd2021

Damage Calculator – Always On Top    

This setting (on the Settings tab) is a checkbox, which is unticked by default. If ticked, the Damage Calculator user interface will always remain on screen in front of other applications (primarily the Flood Modeller main interface).

Treating zero floor areas as valid   

• The ‘Treat Zero Floor Areas as valid’ tickbox is on the Settings tab

• If it is ticked, it will be assumed that any zero floor area assigned to a property is correct (i.e. valid), and that no direct damages will be calculated for this property. 

• If it is not ticked, it will be assumed that a zero floor area assigned to a property is not correct.  A standard property area for the property type (selected by property code) will then be assigned based on the contents of the DefaultFloorArea.csv file. 

• In some cases, a property might appear more than once in a property dataset, e.g. if the property has multiple uses. To accommodate this, the initial entry for the property might have a non-zero area specified and then for all repeat entries the floor area is set to zero (to prevent double-counting of damages for property). Thus, in these situations, it will be correct to accept the zero area and hence calculate associated damage as zero also.
  

Setting alternative property codes 

This option allows fixed mappings to be defined for selected property codes, thus allowing customization of which depth damage curve a property type (in the property dataset) will use in a damage calculation. For example, a more precise property type could be assigned to 999 codes which are typically encounted in the National Receptor Dataset if undertaking calculations in England. 

This option is active by default for all damage calculations, although it can be unticked to turn it off.   Damage Calculator automatically sets up two property code mappings:

• Property code 1 is mapped to the damage curve for code 0 (residential sector average).

• Property code 999 is mapped to the damage curve for code 6 (a low-average damages non-residential property type).

To edit the property code mappings table, the following functions are provided:

• Click on an existing cell and type to edit the entry. Click off the cell to apply the edit.

• Click the Add button, below the table, to add a single, blank row to the table (then type in new values).

• Click on an existing row and then click the Remove button to remove the selected row.

• Click the Save button to write the content of the table to a csv file 

• Click the Load button to load property mappings from a previously saved csv file. The loaded data will be appended to the current table (i.e. current entries will not be lost or replaced).

• Right-click on the table to display menu. Select Add Row to add a single, blank row to the table. Select Restore Defaults to reset the table to only contain the two default mappings (described above). All other entries will be deleted.
  

Discount Rates    

• Discount rates can be found on the ‘settings’ tab of Damage Calculator. 

• Discount rates are applied to annual average damages to calculate present value damages. 

• Two sets of discount rates are present on the setting tab – ‘Standard’ and ‘Other’.  These are applied to damage categories as follows:

• Discount rates can be added and removed using add and remove buttons.

• The discount rates are populated as a default using values from the UK treasury Green Book: https://www.gov.uk/government/publications/the-green-book-appraisal-and-evaluation-in-central-government (paragraphs 2.22 and 2.23).  These can be changed to other values if, for example, calculations are required for a different country. 

Additional damages capping method - Capping and Writeoff of Additional Damages Related to Property Flooding

If a PVD calculation is undertaken applying capping or writeoff settings then damage calculator also applies capping and writeoff to the additional damages related to property flooding. The calculation methods applied and the additional data requirements for these are described in this section.

Additional Data Requirements

Market values for properties must be set up in the property dataset for capping and writeoff calculations to be undertaken.  This is done by adding an extra field to the property dataset (csv text file or shapefile) entitled “MarkVal” and populated with numerical market values.  If working in England, market values may be obtained from the FHRC MCM.  

• Capping to market value – for each property, if the ‘apply capping’ box is ticked, damage calculator will determine the year in which direct property PVD damage equals or exceeds the specified market value.  After this point, the property is considered ‘capped’, and no further direct damages are calculated.  Furthermore, no additional damages related to property flooding are calculated. 

• Write-off at specified AEP - If the ‘apply write off’ box is ticked, damage calculator will compare the onset of flooding for that property with the specified writeoff %AEP for each scenario / epoch.  If a property floods more frequently than this, it is considered ‘written off’ in the year where this occurs.  After this point, no further direct damages are calculated.  The market value of the property is discounted in the year of writeoff, and the discounted market value added to the total damages.  Furthermore, no additional damages related to property flooding are calculated.  It should be noted that writeoff is calculated for upper floor properties, to represent the fact that if the ground floor of a property is written off, the upper floor is also likely to be uninhabitable.  If this is not required, the property should be deleted from the property dataset.

• If a property is subject to both capping and writeoff, damage calculator will check for which occurs earliest, and apply that. If a property is both capped and written are applied, total direct property damages (consisting of the sum of direct flood damages plus the discounted market value in the year of writeoff) may still not exceed the market value, and will therefore be capped to the market value.