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GIS and Natural Hazard Management

Philip J Burden
Philip J Burden
GIS Business Manager
Khatib & Alami CEC

The last twelve months has seen numerous well-publicized catastrophic natural disasters occur throughout the world, including the tsunami of Asia, several hurricanes of the USA, and the earthquakes of Pakistan/India. What each of these events has in common aside from the extent of loss of life, livelihood and materials, was the lack of preparedness of authorities to react to each event. Now that the events have passed and communities are back on the road to recovery, many observers are commenting on what could have been done better. There is an old saying of being “wiser after the event” which seems particularly true when such extreme events occur. This paper describes an approach to being better prepared to handle devastating events, and where GIS technology has a role to play.

What is Disaster Planning
The term disaster is used to describe an event with results in much human and/or property damage. Disaster planning is all about having in place a comprehensive disaster plan that ensures a rapid response when an extreme event occurs. Disaster plans describe how organizations should deal with a disaster. With such plans in place and a coordinated approach to handling an extreme event, these plans can help to reduce the amount of human and property loss.

Types of Disasters
Disasters can be categorized in two forms, either natural or man-made. Natural disasters are natural processes or phenomena occurring in the biosphere that may constitute a damaging event. They can be classified as earthquakes, volcanic activity, mass movement (landslides, rock falls, avalanches), floods and mudflows, storms (hailstorms, blizzard, rain, wind, tropical cyclones, storm surges), drought, desertification, heat waves, sand or dust storms, fire. Man-made disasters are man-induced phenomena that may constitute a damaging event. They can be classified terrorism, war, and engineering faults.

The Economic and Human Cost of Disasters
The world is becoming increasing more inhabited which is impacting our environment. This leaves our populations more vulnerable to disasters. In the past 20 years, natural disasters have killed over 3 million people, and inflicted injury, disease, homelessness and misery on over 1 billion people in addition to causing billions of dollars of material damage. In 2004, it was estimated that the annual global economic costs related to disaster events average US$629 billion per year, five times that of 20 years ago. In 2003 there were about 700 natural disasters.

Below are a few statistics on the human and economic losses experienced from recent disaster events.

EventDeathsHomelessnessEconomic cost
Kobe Japan 1995 earthquake 5,100 300,000 $126 billion to repair basic infrastructure
Izmit Turkey 1999 earthquake 18,000 300,000 $13 billion repair bill
Bam Iran 2003 earthquake 41,000 75,000  
Ash Wednesday Fire, Victoria Australia Feb 1983 76 2,400 AUD $400 million property loss
October Fire Siege 2004, California USA 24 3,700 cost of fire $12 billion
Hurricane Andrew, Florida USA, Aug 1992 26   $26.5 billion in damages
Heat wave, France, Aug 2003 15,000      
Ice Storm, Canada, Jan 1998 28 600,000 $5.4 billion in damages
Exxon Valdez oil spill 1989    $2.5 billion cleanup costs alone
World Trade Centre – building collapse on September 11, 2001 2,700      

Figure: Economic losses resulting from natural disasters 1950-2001

In years gone by, emergency managers were tasked with focusing on preparing for and responding to emergencies. Today, the emphasis is increasingly on minimizing the effect of disasters before they happen through coordination and cooperation between many agencies, although in light of the recently publicized disasters, much more still needs to be done.

Preparation is the key to mitigating disaster events. The World Bank and the USGS in a recent study estimated that economic losses worldwide for natural disasters in the 1990s could have been reduced by $280 billion if $40 billion had been invested in prevention measures. Those organizations taking steps to minimize disaster effects are preparing disaster plans and ultimately working by these plans when an extreme event occurs.

Technology is increasingly being used to assist in the preparation of disaster plans, assisting in operational activities following a disaster event, and assisting in the long-term recovery planning and monitoring processes. GIS, with its capability for displaying, managing and modeling spatial data is one of the technology tools increasingly being used.

The Disaster Cycle
The Office of US Foreign Disaster Assistance describes a disaster in terms of a cycle of emergency management tasks, each preceding task leading to the next. And with each new disaster, further knowledge is attained from the lessons learnt. These can be incorporated back into a disaster plan to improve the preparedness and response measures. The main facets of the disaster cycle are:

  • Identification & Planning;
  • Mitigation;
  • Preparedness;
  • Response; and
  • Recovery

Each of these facets is described in greater detail below, and how GIS can be utilized.

Identification & Planning
Once an emergency management team/organization has decided to prepare a disaster plan, one of the first steps required is to identify possible hazards, assets at risk and the location of various support facilities. First the extent of the geographic area to be covered by the disaster plan needs to be delineated. This could be an entire country or state, a city, or a local community. Consideration also needs to be given to administrative jurisdictions covered/crossed. Once the extent of the geographic area has been determined, the different types of hazards that can threaten a specific area need to be identified. These can be based on past experiences or the scientific body of knowledge for predicting treats to a specific area.

As each geographic area is different, so too are the threats. For example, around the equator there is greater likelihood of severe storms (hurricanes, cyclones, typhoons) and flooding, whilst a location that is surrounded by heavily timbered forests and commonly encounters electrical storms, is more likely to be threatened by fires. Local geography also comes into consideration, e.g. Low lying areas are more subjected to floods than high lying areas. Steep sided slopes in areas of high precipitation are more likely to be subjected to land slides or slippage. The time of year also needs to be considered, e.g. fires are more prevalent late in the summer when grasslands and forests are tinder dry.

Figure: Layers of information utilized in a disaster management system
Other types of information that are important for consideration includes infrastructure and facilities data such as the locations and specifics of law agencies, medical facilities, evacuation areas, communications centers, transport networks, emergency power and water supply, shelter areas and burial centers that can be used when an extreme event occurs. In addition, information such as property details, geology, hydrology, soils, vegetation, transport networks, contours, are also useful.

Once this information has been collected it can be stored in a GIS where the data can undergo further modeling, analysis and display to help identify if patterns exist as to where and when disasters repeat themselves and which areas are more at risk than others.

Once the types of hazards likely to impact a given area have been accessed and understood, the areas of most vulnerability can be easily identified from maps. Master plans can be formulated to address these areas of vulnerability. For instance, in flood prone areas, a review of municipal zoning could be undertaken and recommendations made to restrict new buildings in the areas subject to most flood inundation, instead leaving these places as open public areas; river bank levees could be designed and constructed, etc.

Mitigation measures are usually left to the local, state or federal authorities. Whilst many authorities in developed nations are now being proactive in taking measures to reduce the impact of disasters, many developing nations are waiting until after an extreme event has occurred before addressing the issue.

In either case, GIS analysis is being used to assist authorities identify areas where mitigation effort should be concentrated. The first example shown below depicts areas at risk to flood [red being high risk, yellow being medium risk and green being low risk], whilst the second example shows areas at risk to landslide [areas depicted in orange to red being most at risk]. Using such maps generated by GIS, the authorities can then review policies such as building codes for these specific areas, rezoning effected areas, and/or develop a program of civil works to minimize potential risks.

Example 1- Flood risk map

Example 2 – Landslide risk map

Changing building codes so that building structures are raised above flood peaks, building water levees, building basement structures to withstand earthquakes, clearing zones around houses in fire risk areas, are just some of the ways that authorities and individuals are working towards minimizing the impact of extreme events when they occur.

It is important to subdivide an area up into zones of management and to disseminate this information to the various authorities so that everyone is clear as to who has jurisdiction over an area during an extreme event. Without these management zones, chaos and duplication of effort can result. Within each zone, the number and type of each support facility able to assist in responding to a disaster needs to be delineated on maps and communicated to all concerned authorities.

For each management zone, it is important to identify how many and the location of:

  • structures such as sports stadiums, schools or shopping centers available that can be used for emergency shelter, outside of the reach of the identified treat;
  • medical centers, the type of facilities they have and how many casualties they can handle;
  • evacuation points close to the identified emergency shelters suitable for landing helicopters;
  • emergency response organizations (voluntary, fire, law, search & rescue etc) having facilities with appropriate machinery (response vehicles, generators, emergency supplies of tarps, tents, blankets etc);
  • cemeteries or areas that can be used for burial at a distance from the identified emergency shelters;
  • the shortest path and alternate routes between various locations and facilities
  • backup communication systems, power generation, water purification plants.

If insufficient facilities exist within a zone, either the zone boundary needs to be re-adjusted or facilities need to be established. GIS analysis can be used to help identify the zone boundaries having mapped what was available. It can also be used to quickly identify where deficiencies exist.

Figure: Results of GIS analysis depicted areas of limited facilities
In addition to management zone maps, maps need to be communicated to the general public identifying the location of support facilities / evacuation routes as well as guidelines as what to do when an extreme event occurs. The guidelines will identify who should receive warnings about potential hazards, its severity, when, how often, and by which means – newspapers, TV, radio, or emergency personnel door knocking.

The map below shows evacuation routes, points and hospital locations in downtown Charleston to be utilized in Carolina USA in the event of a hurricane.

Figure: Evacuation routes, downtown Charleston




Elements of a Disaster Preparedness Plan
A Disaster Preparedness Plan is a document that is prepared after the preceding steps have been undertaken and forms the means by which all pertinent information can be collected collectively for ease of dissemination. The components of a typical plan include:

  • Hazard identification & Vulnerability Assessment – describes the potential hazards for an area including the probability of frequency, an assessment of the vulnerability, and the preparedness of authorities to react
  • Evaluation of existing authorities – describes the weaknesses and strengths of authorities responsible for handling disasters in an area, and makes recommendations for correcting the weaknesses. Evaluation of the early warning and communication systems is also undertaken
  • Intergovernmental agreements that support hazard mitigation – details agreements between governmental authorities as to the responsibilities and roles of each authority in handling a disaster
  • Mitigation programs – describes various mitigation programs identified to limit the impact of a disaster event, those who are responsible for conducting the programs, and any budgetary considerations identified
  • Evaluation criteria and policies for regular review – details procedures for the regular review for preparedness of an area to handle a disaster. This may include staging mock events and evaluating the responses of participants in order to identify any shortcomings that require correcting
  • Potential losses due to hazard impact – identifies various disaster scenarios and the potential losses given current conditions versus those once the mitigation programs have been implemented. This assists the decision makers to channel funding to the high priority impact areas.

No matter how much preparation may be done, some disasters are unavoidable. When a disaster is identified as being imminent such as a flood or a storm front moving in, or during an event such as a fire, earthquake, or volcanic eruption, emergency managers must decide as to how they will respond to the event. The Disaster Preparedness Plan will provide some procedures and a sequence of tasks that must be taken. The skill of the emergency manager is to rapidly assess the disaster effects and immediately mobilize resources for recovery.

Doing a rapid reconnaissance of the disaster and mapping the location of the effected area can aid emergency managers in deciding how many resources, what type of resources and where best to place the resources to effect maximum response in the least amount of time. As an example in fighting fires, helicopters equipped with GPS units and video cameras fly along the front of a fire at regular intervals. GPS data, together with other up-to-date information such as weather forecast, are transmitted to the command center where it is fed into a GIS system, analyzed and decisions made as to how to tackle the changing fire front.

Figure: Helicopter with GPS and video system feeds data back to a command center where it is
analyzed and decisions made as to locating resources.
The same information fed to the control center can also be made available on the web for transmission to remote locations. With the use of such technology, emergency managers can rapidly redirect resources as needed, allowing fire teams to react in minutes or hours where previously it would take days for information to be received and decisions to be made.

With the emergency response teams deployed into the ‘hot zones’ of a disaster, the recovery phase looks at returning the scene back to normal as soon as is possible. This usually involves two phases of recovery. A short-term phase that restores all vital life-support systems so that a population’s immediate needs are addressed. This may include the provision of temporary shelter, bedding, fuel to cook, and basic food and water needs. As soon as possible, power and water supplies are restored, and debris cleared.

The second longer-term phase sets about rebuilding the community. This may take 10s of years to accomplish. It usually involves incorporating lessons-learnt from the extreme event and may involve changing legislation such as land zoning, building codes, policies, law, etc. Securing support from various relief funding agencies and government authorities will need to be obtained if the recovery efforts are to progress.

Recovery plans will be prepared to guide the vision of the recovery, to return the community back to a better state than that before the extreme event occurred. There will also be a requirement to monitor the progress of the recovery program to ensure that funds are being spent as they were originally intended, and that the rebuilding priorities are being undertaken as originally scheduled.

GIS can be used in the preparation of recovery plans, developing various scenarios and providing visualization of results. Master Plans can be prepared and display using GIS encompassing environmental, community and economic considerations.

Figure: Example of precinct Master Plan
Once the recovery plans have been approved and contracts award, the projects can be tracked using GIS.

Figure: Example of tracking stages of projects using GIS
Disasters cost our society billions of dollars each year. Spending just a fraction on prevention measures and preparations can dramatically reduce the cost of disasters. GIS is a tool that can be utilized throughout the various phases of the disaster cycle radically improving the analysis and presentation of data, from recording details of what has happened in the past, to assisting in analyzing various mitigation scenarios; to mapping the progress of an extreme event as it occurs enabling decision makers to visually see the impact and thus redirect resources as required; to utilizing GIS as a planning tool for future recovery efforts.