• GIS in Emergency Management and Related Area
• Key words in emergency management
• Case study
Emergency management defines as the discipline and
profession of applying science, technology, planning, and
management to deal with extreme events that can injure or
kill large numbers of people, do extensive damage to
property, and disrupt community life.
The role of GIS in managing sudden impact disasters like flood
and fires, rather than on slow onset hazards like radon gas,
water pollution, land erosion, or other natural of technological
hazards that occur gradually over time.
actions that are taken to
eliminate or reduce the
degree of long-term risk to
human life and property
Preparedness is concerned
with actions that are taken
in advance of an emergency
to develop operational
capabilities and facilitate an
effective response to an
Response phase involves actions
that are taken immediately before,
during, or directly after an
emergency occurs, to save lives,
minimize damage to property, and
enhance the effectiveness of
Recovery phase is characterized
by activity to return life to normal
or improved levels
GIS based Resource Management for Natural Hazards
To illustrate, a prototype implementation has been developed
for Chennai city using Arc/Info
This involves location of emergency management facilities
such as temporary shelters, medical relief centers,
telecommunication facilities, food storage and distribution
centers, etc. The resources required for managing disasters,
such as food, medical supplies, vehicles
Vital time is lost in identifying the nearest facility and the
best route to approach it which very often means the
difference between success and failure of a rescue and
The network data model can be used for this
A network is a system of interconnected
linear features through which communication
or transportation of resources is achieved.
The model consists of network links, network
nodes, stops, centers and turns
Characteristics of a network model are
Supply and Demand , Impedance
The network data model elements are Links,
Turns, Stops, Centers, Barrier
Supply and Demand:
For example: A hospital has a specific
number of beds available this is the termed
Streets are assigned to the hospital until the
total demand for those beds matches the
Impedance is the cost associated with the
utilization of the supplied resource
through a network. Distance and time are
commonly used impedance to the utility of
For example no person living on a street
farther than 20 minutes (through
ambulance) may be assigned to that
Elements of Network data model
Links: Links are represented as arc
features and connect to each other
at nodes. Connections between
links are represented using arcnode topological data structure. Arc
represents transportation links, and
their attributes affect the movement
of resources through a network
Turns: - The possible direction changes for resource flow every
node where links connect. Flow can occur from one link through
the node, and onto another link Particular tums often restrict flow
in the network
Stops: Node locations where resources are to be
picked up or dropped off along paths through the
network, Resource demand is the amount of resource
associated with a stop.
Centers: Facilities at node locations which have a
capacity to receive resources from links in the
network, or distribute resources to the network.
Example: hospital, school, etc.
Barrier: Node locations through which resources
cannot flow. Barriers are the only elements Which do
not have any attributes. Barriers are used to prevent
movement between arcs
THE PROTOTYPE MODEL
• The bay area of Chennai between
Royapettah and Parrys has been
selected for the purpose of
• This implementation is for
cyclone disaster management,
but it can be easily extended for
other disasters as well. The bay
area was chosen as it is the
closest representation of a coastal
zone within Chennai city.
PX1(X7/X1+X2+X3)P1 (X7/XI+X5+X6)Pr = df * P x7
Pxi = (Xi/ EXI)P1 +(Xi/∑Xr)Pr
Nxi = df *Pxi
- Length of the arc segment i.
EX' - Sum of lengths of all the segments of the polygon to the left of the segment Xi.
EX- Sum of lengths of all the segments of the polygon to the right of the segment Xi.
Pi- Population of the area to the left of X;
Pr- Population of the area to the right of Xi
Nxi- Population along arc segment Xi who will be in need of the facility - Disaster Factor
For the example network given below, the demand is calculated as follows:
RESULT :The areas to be served by each hospital have been
clearly identified (Figure 1).
It can also be noticed that some intermediate areas have not been
allocated to either of the hospitals.
This is because the capacities of these hospitals have been
exhausted before that demand could be met.
Based on multiple runs of the allocation program an optimal
location has been identified for the location of an emergency
medical facility such that the impedance is minimized .
Also the shortest route, taking barriers into consideration, has
been identified for a sample location.(figure2)
(i) GIS is an appropriate environment
for developing a decision support
system for resource management for
natural hazard mitigation.
(ii) The network module in Arc/info is
ideally suited to address this issue.
(iii) The primary challenge in
developing an effective decision support
system lies in assessing the needs of the
decision makers and accurately
acquiring, representing and updating the
relevant data in the GIS.