HOWAS 21 contains datasets about flood damage affecting private households, industrial buildings, other infrastructure and open areas. Attributes cover the local impact of the flood event, damage to the object (monetary and non-monetary), as well as damage mitigation measures in place. Each record is categorised to belong to one of the following damage sectors (object types being damaged):

• Private households,
• Commercial and industrial,
• Public thoroughfare, road and transport infrastructure,
• Watercourses and hydraulic structure,
• Agricultural and forested land,
• Urban open spaces.

The selection of attributes describing the data in HOWAS 21 is based on catalogues that were developed with the help of experts in flood analysis for each of the sectors (Elmer et al. 2010). These attributes contain crucial information that are required for the analysis of flood damage data and should therefore always be collected. More details can be found in chapter 4 of the book Hochwasserschäden - Erfassung, Abschätzung und Vermeidung (in German).

A subset of all available attributes have been defined as "minimum standard", which are made mandatory for HOWAS 21.

Minimum standard criteria

• Economic sector - classification of the sector where the damage occurred.
• Damage - monetary quantification of the damage.
• Water level - the highest water level during the flood event.
• Temporal context - relation to a flood event, ideally by providing the date when the flooding affected the object.
• Spatial reference - location of the damage occurred, ideally provided as a geographical coordinate pair (lat/lon).
• Data collection method - how the data was collected.

Attributes for private households

The following lists exemplify the main damage information tables for private households. You can find the full list of all attributes collected for a record here.

Flood characteristics at the location of the affected object

• Start, end, duration of inundation at the object
• Name of river causing the inundation
• Maximum water depth
• Maximum flow velocity
• Contamination, flotsam
• Local return period
• Hazard peculiarities, description of hazard at object

Objects characteristics and damage information

• Location of the building
• Building type and characteristics (number of stories, age, quality, net dwelling area, intrusion paths and intake sill, building material, use of the cellar, etc.)
• Value of the building, building damage, damage ratio
• Contents value, contents damage, damage ratio

Damage mitigation

• Knowledge about the flood hazard
• Precautionary measures
• Early warning, lead time
• Emergency measures
• Effectiveness of measures