Geography Reference
In-Depth Information
Box 9.2
Subsidence beneath Kuala Lumpur, Malaysia
Beneath the northeastern part of central Kuala Lumpur
is a highly cavernous buried limestone karst, with
many voids (Figure 9.3). The buried karst plain is
overlain by sands and clays deposited by rivers as the
sea level rose after the last ice age. The sands contain
alluvial tin deposits, the mining of which created pits,
which were later filled. The mining produced two types
of subsidence: that due to the general lowering of the
groundwater table, especially by the pumping of water
out of mine pits; and that due to the sudden collapse
of sediments over sinkholes. Some of the filled pits
have been reclaimed for low-cost housing. In a few
instances, fill has subsided into sinkholes with, in one
place, a row of low-cost houses collapsing into a
reopened hole.
The buried karst now poses serious problems for civil
engineering works (Bergado and Sebanayagan 1987) New
high-rise buildings require deeper foundations than the low-
rise buildings that sufficed until the 1970s. In Kuala Lumpur,
the low-rise structures had their foundations on the stiff clay
layer within the alluvium. Taller multistorey structures require
piling into the underlying limestone. However, the irregularity
of both the karst surface and the cavities within the buried
karst means that foundation investigations have to be
particularly circumspect. Drill holes may strike limestone,
unaware as to whether it is buried rockfall material or a
pinnacle, while a neighbouring hole might pass through
several more metres of alluvium before hitting limestone.
Special precautions had to be taken when constructing the
Petronas Twin Towers, the world's tallest building at the time.
On the other, the different databases on gas and water
pipes, telephone and electricity cables, postcodes,
housing stock, census data, health status, locations of
services and recreational facilities for individual cities
are becoming more integrated, so that everything
from air quality to ground conditions and waste
disposal patterns can be accessed through a single
database or GIS. Such 'smart' cities can also become
