The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vo I. XXXVII. Part B4. Beijing 2008
the area of Btiyukcekmece covers residential areas on low-
levelled terrain that finally can affect 30,000 people by a Tsu
nami since they live in the red coloured zone as shown in Fig
ure 6. Such risk maps easily can indicate city planners where
risk-factors must be taken into account or at least to define clear
rules for constructing objects in these risky regions. Maps as
shown above also support the Crisis Management Team to de
tect sensitive parts of the city and assist them in defining ways
to access these areas for helping the people.
Figure 6. Areas of a certain run-up risk for Tsunamis overlaid with land-use data and population density of residential areas.
[Kemper 2006]
Many scientists in our discipline use GIS in combination with
remotely sensed data and/or aerial photos to extract the land-use
and analyze them, commonly in combination with spatial or
non-spatial ancillary data. Terrain-models are used for the
orthorectification process but as shown above, they can do more.
There are various possibilities to contribute to risk mapping out
of such data-sources. Risk-maps also help the decision makers
to understand the needs for a sustainable planning and support
an integrated Crisis management. Crisis Management and the
needed reorganisation of a city can find acceptance in the popu
lation more easily by presenting these risk-maps than any other
arguments can do. Like that, these maps have a big importance
to transport political decisions which are needed for a success
ful crisis management and so finally for a better help for the
people. 6
6. ENGINEERING AND ARCHITECTURE
Concerning the quality of architecture, Istanbul has to deal with
difficult “heritage”. This heritage is, the so-called Gececondu
areas. These Gececondus are illegally built-up areas with small
but also bigger residential buildings. Usually after some years,
they were legalized by the city administration. Owners and their
relatives, means that they were not built by engineering rules,
built-up these houses. Depending on the political situation, es
pecially during election terms, they were legalized later and
then often enlarged with additional stories, a extremely critical
activity. In most cases, these buildings are weak and not stabile
against earthquake shocks. Some building even collapsed with
out any earth shocks. Often also the foundation of buildings is
weak especially if the building where increased. The scientific
knowledge in constructing shock-proven buildings is well
known in Turkey but has only rarely applied to the real work.
To validate all buildings in Istanbul on their stability causes an
enormous work. Nevertheless already, the over-planning of the
former Gececondu areas takes place, which can be seen as a
good chance for planning new residential areas that consider the
risk and make live more safety. Actually, there is a big need to
get data of the buildings about their static-stability, their use and
their internal infrastructure e.g. if there are heavy machines,
lifts, gas-pipelines... It is also worth to know how many people
in which daytime stay inside the building. Are Emergency ex
ists available and do they really guide to a safer place? To col
lect these data, field mapping is very limited since it accesses
only the outside part of the building. Oblique imaging tech
nologies e.g. pictometry, can assist in same way as they do for
home security analysis in other parts of the world. Such images
can help engineers and other specialists to validate the static of
a building since they enable the view to typical constructive
elements of the building.