In addition to the hazard analysis, a comprehensive risk assessment requires an analysis of the damage potential, which categorises buildings according to their type of use. The assessment of the damage potential considers the possible impact of heavy rainfall events on various sectors (e.g. life and limb, environment, industry). The aim of assessing the damage potential is to determine, localise and illustrate protection requirements and damage susceptibility and to assign damage potential classes. The damage potential is evaluated independently from the hazard, the potential inundation areas are not taken into account yet. Togehter with the hazard they are the basis for further risk and vulnerability analysis.
Method and required data
The damage potential analysis can be performed in different depths (level of detail). A distinction is made between area-related (simple) and detailed damage potential analysis; a combination is also possible. The damage potential of an area/object/building is largely determined by the type of use (e.g. residential, commercial, critical infrastructure etc.). Depending on the utilisation, flood damage can include material damage (e.g. property damage, damage to buildings) and immaterial damage (e.g. personal injury, environmental damage, damage to cultural heritage). The classification of the damage potential was based on the German DWA-M 119 standard and adopted to the local situation using expert opinion of Jordanian stakeholders (n=4). All buildings within the study areas are classified based on their predominant use following the categorisation in table 1.Like the hazard analysis, the damage potential is classified into flour classes (1: low, 2: moderate, 3: high, 4: very high (critical)).
Tab.1: Damage potential classification within CapTain Rain
| Object use name | Object use description | Damage potential class |
|---|---|---|
| Energy infrastructure | Major energy production/providing facilities. Class terminology is adopted from Scheid 2018 based on BMI 2011 (e.g., transformers, gas stations, energy production plants). | 4 |
| Transportation network | Major road networks, that if damaged, cause a severe hindrance to societal functions. Class terminology is adopted from Scheid 2018 based on BMI 2011 (e.g., tunnels/underpass, major transportation roads). | 4 |
| Water infrastructure | Sensitive water structures that if damaged, cause a severe hindrance to societal functions. Class terminology is adopted from Scheid 2018 based on BMI 2011 (water towers, manholes, water supply network). | 4 |
| Health or care facilities | Critical health or social care establishments that if damaged, cause a severe hindrance to societal functions (e.g., hospital, clinic, pharmacy, nursing home, Children's home). Class terminology is adopted from Scheid 2018 based on BMI 2011. | 4 |
| Monument area | Cultural heritage sites. Class terminology is adopted from Scheid 2018 based on BMI 2011 (e.g. archeological monuments, cultural heritage sites). | 4 |
| Worship place | Religious buildings such as mosques and churches with a high importance as emergency shelter. | 4 |
| Kindergarten or primary school | Kindergarten or primary schools, where young children are at daytime. | 4 |
| Police or fire station | Police or fire stations, which may be on duty during a flash flood event. | 4 |
| Public building | Major government structures that, if the building is out of service, some societal functions might be affected. | 3 |
| Bank and finance | Major banks buildings that, if the building is out of service, some societal functions might be affected. Class terminology is adopted from Scheid 2018 based on BMI 2011 (e.g., banks). | 3 |
| Large Commercial | Buildings that have a predominant commercial use. Class terminology was derived from Jordan Building Law (2022). | 3 |
| Local Commercial with basement | The same as "Local Commercial" but with basement. | 3 |
| Multifunctional building | Buildings with a mix of usages within the same building (e.g. residential, commercial and offices). | 3 |
| Social housing | Buildings that provide social housing for the economically disadvantaged with large built-up to parcel ratio (only 2 meter front and back setbacks). | 3 |
| Residential building with basement | Building for residential use with basement. | 3 |
| Storage (undifferentiated) with basement | Building used for storage with basement, not differentiated by GAM. | 3 |
| Industrial storage | Building used for storing industrial products. | 3 |
| Educational facility | Educational facility such as secondary school, college, university and other private school. | 3 |
| Underground car park | Underground Parking. | 3 |
| Unclassified building with basement | Buildings not included in GAM GIS database, lacking information on use category. | 3 |
| Local Commercial | A local commercial building is used for commercial intensions and located inside a residential building within neighborhoods while the building is mainly for residential use. Class terminology derived from Jordan Building Law (2022). | 2 |
| Light industry | Industrial building with a minimum parcel area of 1000 m². Class terminology derived from Jordan Building Law (2022). | 2 |
| Medium industry | Industrial building with a minimum parcel area of 2000 m². Class terminology derived from Jordan Building Law (2022). | 2 |
| Hotel | Hotel where tourists are at nighttime. | 2 |
| Residential building | Buildings for residential use. | 2 |
| Storage (undifferentiated) | Sites used for storage, not differentiated by GAM. | 2 |
| Graveyard | Sites for human burials. | 2 |
| Parking space | Open parking sites without roof structures. | 2 |
| Unclassified building | Combines all buildings, which were added by us and were not included in GAM dataset. | 2 |
| Park, green area | Parks/green spaces for leisure activities, sports and children's playgrounds. | 1 |
| Woodland | Large wooded areas in urban space as important habitats that could suffer damage in the event of flooding (less flood-tolerant tree species). | 1 |
The quality and level of detail of a damage potential analysis depends on the data availability and accuracy. Input data includes land use land cover maps, infrastructure data and digital city maps (like OpenStreetMap). The analysis can be expanded by taking other parameters into account, e.g. basements, businesses using water-polluting substances, etc. Within the CapTain Rain project we used for Amman the shapefiles from GAM and freely avaliable OSM datasets and for Wadi Musa/Petra the OSM datasets, additionally digitized buildings based on an aerial photograph (PDTRA) and building usages information from Google Maps and Google Earth.
Challenges
While the flood hazard can be determined quite reliably, the analysis of potential damage caused by heavy rainfall-related flooding is subject to considerable uncertainty, particularly in the case of monetary damage. In addition, the determined damage potential is a snapshot in time and should be reviewed at regular intervals to take account of future developments and possible changes. The availability and accuracy of the required data can also be a problem.
Flash flood damage potential map
The results of the damage potential analysis can be evaluated and visualized in a map, with areas and objects highlighted in different colours to clearly indicate the potential damage levels (e.g. red: very high damage potential). Depending on the size of the study area, it may be advisable to produce detailed maps in addition to overview maps for the entire area. This will ensure that both the overall study area and small-scale results are clearly visible in the finalised maps.
Fig.1: Flash flood damage potential map for Downtown Amman
Flash flood damage potential maps Amman
Damage Potential map Amman (complete)
Damage Potential map Amman (Downtown)
Flash flood damage potential map Wadi Musa
Damage Potential map Wadi Musa
References
- DWA, 2016: German Guideline, DWA-Merkblatt 119. Risikomanagement in der kommunalen Überflutungsvorsorge für Entwässerungssysteme bei Starkregen (Risk management in municipal flood prevention for drainage systems during heavy rain), DWA German Association for Water, Wastewater and Waste, e.V., Hennef, ISBN: 978-3-88721-393-0.