Geoinformation for Disaster and Risk Management - ISPRS
Geoinformation for Disaster and Risk Management - ISPRS
Geoinformation for Disaster and Risk Management - ISPRS
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Tiered conceptual framework <strong>for</strong> population<br />
estimation<br />
A tiered conceptual framework is proposed <strong>for</strong> the<br />
Ahmedabad case study, which is an applicationdriven<br />
approach, aimed at developing population<br />
data <strong>for</strong> input to risk model parameters. The selected<br />
levels correspond to the operating unit of analysis,<br />
ranging from postcode/district/city boundaries <strong>for</strong><br />
risk-sensitive planning, to a single building <strong>for</strong><br />
response <strong>and</strong> recovery missions. This framework,<br />
which may ultimately be st<strong>and</strong>ardised <strong>for</strong> other<br />
cities, poses a number of technical challenges.<br />
Figure 1: Examples of buildings affected by the 2001 Gujarat earthquake:<br />
(Left) heavily damaged residential building,<br />
(Right) multi-storey building that has fallen on one side (Bhuj, India) (Image courtesy by M. Markus, 2001)<br />
For each level, the relevant data have to be identified,<br />
their availability verified, <strong>and</strong> their accuracy<br />
evaluated. For example, data from Indian Census are<br />
only updated on a decadal basis. In order to integrate<br />
census in<strong>for</strong>mation with other data such as remote<br />
sensing imagery, the relevant census data should be<br />
projected to match the image acquisition year.<br />
Moreover, the significance <strong>and</strong> accuracy of Census<br />
data as well as other statistical data have to be<br />
carefully evaluated.<br />
The assumption that data <strong>and</strong> in<strong>for</strong>mation reflect<br />
reality should be h<strong>and</strong>led with care, as despite<br />
ef<strong>for</strong>ts to identify uncertainty, residual uncertainties<br />
will always remain. Cautious evaluation of available<br />
data that includes cross calculation <strong>and</strong> statistical<br />
analysis should lead to a data product that can be<br />
called the most likely status.<br />
In addition to data-related uncertainties, modelbased<br />
uncertainties also need to be considered. The<br />
modelling of population is typically based on<br />
relationships that are assumed to be true <strong>for</strong> the test<br />
site (<strong>for</strong> example, number of people resident at<br />
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