Author(s): Dr. Manzul Kumar Hazarika

Elements-at-risk are the objects such as buildings, infrastructures, population etc. that are exposed to one or more hazards and they are likely to be get adversely affected by the hazards. The way in which the amount of elements-at-risk are characterized (e.g. as number of buildings, number of people, economic value or the area of qualitative classes of importance) also defines the way in which the risk is presented to the end users. There are many different types of elements at risk, and also many different ways to classify them. Table below gives an example of such a classification.

Classification of elements at risk

Physical elements

Buildings: Urban land use, construction types, building height, building age, total floor space, replacement costs.

Monuments and cultural heritage

Population

Density of population, distribution in space, distribution in time, age distribution, gender distribution, handicapped, income distribution

Essential facilities

Emergency shelters, Schools, Hospitals, Fire Brigades, Police,

Socio-economic aspects

Organization of population, governance, community organization, government support, socio-economic levels. Cultural heritage and traditions.

Transportation facilities

Roads, railway, metro, public transportation systems, harbor facilities, airport facilities.

Economic activities

Spatial distribution of economic activities, input-output table, dependency, redundancy, unemployment, economic production in various sectors.

Life lines

Water supply, electricity supply, gas supply, telecommunications, mobile telephone network, sewage system.

Environmental elements

Ecosystems, protected areas, natural parks, environmentally sensitive areas, forests, wetlands, aquifers, flora, fauna, biodiversity.

Source: Guidebook on Multi-hazard Risk Assessment, ITC.

Elements at risk inventories can be carried out at various scale levels, depending on the requirements of the risk study. The table below provides and an overview of scales in which the elements-at-risk can be mapped and the risk assessment can be done at these scales based on certain basic spatial units such as municipalities, wards or even individual buildings. However, risk assessments at individual building level are often avoided due to large volume of information required, high cost, uncertainty in data and models, and more importantly legal consequences.

Elements at risk mapping versus mapping scale

Elements at risk type

Scale of analysis

Small

< 1:100,000

Medium

25,000-50,000

Large

10,000

Detailed

>1:10,000

Buildings

By Municipality

  • Nr. buildings

Mapping units

  • Predominant type ( e.g residential, commercial, industrial)
  • Nr. buildings

Building footprints

  • Generalized use
  • Height
  • Building types

 

Building footprints

  • Detailed use
  • Height
  • Building types
  • Construction type
  • Quality / Age
  • Foundation

Transportation networks

General location of transportation networks

Road & railway networks, with general traffic density information

All transportation networks with detailed classification, including viaducts etc. & traffic data

All transportation networks with detailed engineering works & detailed dynamic traffic data

Lifelines

Main power lines

 

Only main networks

  • Water supply
  • Electricity

 

Detailed networks:

  • Water supply
  • Waste water
  • Electricity
  • Communication
  • Gas

Detailed networks and related facilities:

  • Water supply
  • Waste water
  • Electricity
  • Communication
  • Gas

Essential facilities

By Municipality

  • Number of essential facilities

As points

  • General characterization
  • Buildings as groups

Individual building footprints

  • Normal characterization
  • Buildings as groups

Individual building footprints

  • Detailed characterization
  • Each building separately

Population data

By Municipality

  • Population density
  • Gender
  • Age

 

By ward

  • Population density
  • Gender
  • Age

 

By Mapping unit

  • Population density
  • Daytime/Nighttime
  • Gender
  • Age

People per building

  • Daytime/Nighttime
  • Gender
  • Age
  • Education

Agriculture data

By Municipality

  • Crop types
  • Yield information

By  homogeneous unit,

  • Crop types
  • Yield information

By cadastral parcel

  • Crop types
  • Crop rotation
  • Yield information
  • Agricultural buildings

By cadastral parcel, for a given period of the year

  • Crop types
  • Crop rotation & time
  • Yield information

Economic data

By region

  • Economic production
  • Import / export
  • Type of economic activities

By Municipality

  • Economic production
  • Import / export
  • Type of economic activities

By Mapping unit

  • Employment rate
  • Socio-economic level
  • Main income types
  • + larger scale data

By building

  • Employment
  • Income
  • Type of business

 

Ecological data

Natural protected areas with international approval

Natural protected area with national relevance

General flora and fauna data per cadastral parcel.

Detailed flora and fauna data per cadastral parcel

Source: Guidebook on Multi-hazard Risk Assessment, ITC.

One of the most important spatial attributes for elements-at-risk inventory is the land use. The land use determines to a large extend the type of buildings that can be expected in the unit, the economic activities that are carried out, the density of the population in different periods of the day, etc.

(v. 27/3/2016. 13/6/2016)