In: Wagner W., Szekely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B 
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imagery in combination with morphometrical features (Tapas et 
al., 2010) were developed and tested within different areas with 
encouraging results 
These latest studies focuses on the integration of data with 
different spatial resolutions together with data derived from 
elevation models, as well as other segmentation rules within 
landslide algorithms. These are relevant contributions but they 
are limited in terms of the data variety. Our study considers that 
besides the favorable factors for landslides landslide, the 
triggering factors like the amount of precipitation that reaches 
the terrain surface can complete the segmentation rules for 
landslide bodies. Testing the proposed algorithm on a 
representative case study from the Prahova Valley in the 
Subcarpathians can help the improvement of the existing 
methods for landslide mapping and classification 
The area is characterized by high slopes gradients with values 
between 15-30°, specific to most of the hillslopes within the 
area, medium drainage density, with values between 0.3-1 
km/km 2 
The natural vegetation of the area was replaced during the last 
two centuries by the secondary vegetation, with a high 
deforestation degree (50-60%) The human activity has relevant 
impact for this area, with a population density of about 50-75 
inhabitants/km 2 (higher values in the Breaza town built-up 
area). There are 10 built-up areas, mostly rural areas attached 
since 1968 to the Breaza town (mainly scattered farms).The 
local economy is dominated by agricultural activities, based 
mainly on grazing and orchards. These are favorable conditions 
for landslides 
1.3 Study area 
2. MATERIALS AND METHODS 
The study area we focuses our analysis is the Breaza town 
administrative area, which is situated along the Prahova River 
Valley within the Prahova Subcarpathians (SE Romania, 
Curvature Subcarpathians). This area has an interesting 
situation because of the great density of landslide bodies (156 
bodies were mapped by Sandric, 2008, on a surface of about 
70km 2 ). They are covering almost all the slopes in a complex 
lithological and structural-tectonical background. Breaza town 
is located along the main transcarpathian railroad and European 
road between Bucharest and Brasov. 
From the geological point of view, the study area superposes on 
a nappe system, thrusting each other from the North to the 
South. These nappes belong to the Cretaceous and the 
Palaeogene flysch areas, as well as to the Upper Cretaceous and 
Lower Miocene posttectonic sedimentary covers. The folds 
configuration, as an effect of the tectonical transformations, 
shows a system of parallel synclines and anticlines, oriented 
from the East to the West. 
The most affected lithostratigraphic units are: Gura Beliei marls 
(Upper Cretaceous posttectonic sedimentary covers) which 
produce rotational and translational slides, earthflow; molasse 
deposits of Doftana (marls, clays, sandstones of Lower 
Miocene posttectonic sedimentary cover ) affected by rotational 
and translational slides, Pucioasa Strata (marls, clays of 
Paleogene Flysch) affected by earthflow, rotational and 
translational slides. 
Figure 1. Location of the study area 
2.1 Materials 
The analysis is based on image segmentation techniques for an 
object-oriented classification. These datasets were integrated in 
digital format in order to define the landslide body’s 
configuration according to their spectral and morphometric 
features (McDermid, Franklin, 1994, Tapas et al., 2010). Our 
main interest was to extend the analysis with other relevant 
datasets like lithology and the amount of precipitation that 
reaches the terrain surface 
The high resolution imagery consists in digital orthophotos 
acquired from the National Agency for Cadastre and Real Estate 
Advertisement (ANCPI Bucuresti). The acquisition date of the 
air-photos is July 2005. Images are in natural colors and have a 
spatial resolution 0.5 m. They are co-registered with 1:5000 
scale topographic maps. These images were integrated within a 
digital mosaic covering the whole administrative area of Breaza 
town. Some problems are featuring these images: the 
orthorectification errors (limited) and their temporal resolution. 
They are summertime imagery limiting the identification of a lot 
of the slope morphodynamics features (including landslide 
bodies). Forests and meadow vegetation occurs in green 
signatures while eroded areas are in shades of light brown. 
Visual interpretation opportunities of this imagery were limited 
by the uncertainty of the limits of the superficial and shallow 
landslide bodies. Field mapping and observation was usually 
applied for the validation of the landslide inventory based on 
aerial imagery. 
Since the year 2008, new imagery was obtained for the 
Subcarpathian sector of the Prahova Valley by Ionut Sandric, in 
order to validate and to improve the landslide inventory for the 
Breaza town administrative area. The high resolution digital 
imagery obtained with a Canon 400D camera from a Cessna 
aircraft is frequently oblique which are usually better for 
landslide bodies’ interpretation. Some of the nearly vertical 
images were geometrically corrected and used for landslide 
body extraction in digital format The DEM was obtained using 
the ANUDEM interpolation method implemented in ArcGIS 
Desktop 9.3.1 - ArcINFO version. The layers used in the 
ANUDEM method are: contours with intervals from 5 to 5 
meters, point elevation and rivers, all collected from the 
topographical maps at a scale of 1:5000. The spatial resolution 
of the DEM was 2.5 meters and it was calculate by dividing the 
contour intervals by 2. The accuracy of the DEM was tested by 
comparing random selected point elevation with the values of 
the generated surface. The standard deviation was 3.6 meters 
(Sandric, 2008). From the DEM we derived the slope gradient, 
plan curvature and profile curvature, which we assumed that