Landslides
are common on the eastern side of Büüyükçekmece Lake along the coast near the
Marmara Sea, because of the anthropogenic activities such as excessive
development, excavation, cutting, filling and geological features, but in this
study, the study area doesn’t involve area that along the coast.
Figure-2
shows the covered study area on aerial photo. As we see settlements
concentrated near the roads that are E-5 Highway and Büyükçekmece Roads at top
of the hill because of the aspect, view and availability.
Figure- 3-4
shows elevation values of Büyükçekmece. Elevations decrease from top to down of
hillside by every 5m that highest one is 200m and lowest one is 50m. Also,
settlement had seen between 200-110m elevations as had shown in Figure-9-10. At
lower parts have few buildings because of much clayeysoils and much water
content in area and view, aspect, too.
In addition, Figure-9 is a 3 Dimensional
view of study area that combined with contours in Figure-10.
General
geology map of European Side of Istanbul in Figure-5 involves Büyükçekmece
area. Main geology character of Büyükçekmece is Gürpınar Formation that the
most problematic land of the Istanbul in terms of landslides. It is composed
of150-400m thick clays and it is not good land for building development as we
understand from this paper and maps. Also, landslides are affected by seismic
motions. This processes are increasing landslides and hit houses. In Figure-6
around of Büyükçekmece is covered with clay soil characteristics, for this
reason, quakes are more affected as seen as in Figure-7, because seismic waves
are diffusing and moving easier in soft soils, by the way, it gives more damage
and it is more dangerous.
There is
explanation and an example of morphological mapping in Figure-8. It shows that
increasing angle and height of slope promote landslide processes mostly.
Figure-11-12
show slope and aspect map of study area by done 3 Dimensional elevation map. In
slope map, highest slope is between 78-88 values. Aspect map shows the
direction to the sun of area and houses that generally towardsto north and
east directions.
According to
field trip observations, landslides are concentrated between 84m and 154m
elevations as shown in Figure-13-14 by
letters and yellow field trip points. In contrast to this, at this points,
there is very few damaging in building and roads, especially landslides had
seen on unsettled land of study area and should be realized at growing shapes
of trees at present clearly as seen at Photo-1-2 according to field trip
research.
In addition,
there is good examples of three types of mass movements that are falls, slides
and flows at photos. Mostly at photos had seen mudflow and sliding types of
mass movements because because of clat soil formation and high water content,
also, the settlements have big risk of landslide in near future by the time.
Beside of this, there is a lot of cracks with clayey soil type at study area as
seen at Photo-3-4 and they are carrying very big risk on built settlement.
Moreover, in Figure-15-16 had shown danger area and
potential danger area. Figure-15-danger area
map is a reference for present landslides that studied in this
paper but Figure-16-potential danger
area is a reference for near future landslides approximately as in 10 years.
These maps are very useful data for engineers, constructers and municipality
documentators to mitigate future landslides and to built new settlements.