Geoscience Reference
In-Depth Information
Table 5.1
Area (%) of altitude belts
a
(by Mihailov, in: The natural and economic potential of the
mountains in Bulgaria,
1989
)
Mountain region
Rila and
Rodopy
Kraishte-Sredna
Gora
Stara
Planina
Tot a l for a l l
mountain regions
Altitude belts (m)
Lowlands (0-200)
1.3
4.8
8.5
5.3
Hilly lands (200-600)
27.7
39.4
57.0
43.3
Low-mountain
(600-1,000)
23.2
39.1
23.4
26.5
Mid-mountain
(1,000-1,600)
35.1
15.9
9.7
19.8
High-mountain
(1,600-2,200)
9.4
0.7
1.3
4.0
Alpine (> 2,200)
3.3
0.1
0.1
1.1
Total
100
100
100
100
a
Percentages express the ratio to the total area of the mountain regions
Osogovo-Rhodopes massif represent a barrier to the invasion of warm air masses
of marine origin from the South, their influence being more noticeable only along
the meridional valleys of the Struma, Mesta and Maritsa Rivers, as well as in the
adjacent mountain slopes, especially in the Pirin, Slavyanka, East Rhodopes, Sakar
and Strandzha mountains.
The evaluation of the direct role of relief in formation of the natural environ-
ment is related first of all to favorable or restricting conditions for construction
and agriculture from the viewpoint of terrain stability in the tectonic-seismic and
lithological-petrographic respect and the sustainability/susceptibility of the soil
cover to destruction-erosion processes in the case of bigger dismemberment and
slopes. The results from relief assessment in relation to these two aspects with the
use of rating estimates categorize the mountain territories as follows (Mihailov and
Vaptsarov,
1975
):
•
with unfavorable conditions for construction and agriculture - the main Stara
Planina Mt. chain in the middle and western part and the Osogovo-Rhodopes
massif without the Middle Struma valley, the Gorna Arda basin and the Haskovo
hilly district;
•
with medium favorable conditions - the Fore Balkan, Kraishte-Sredna Gora,
Sakar-Strandzha and Middle Struma valley and the Gorna Arda basin;
•
with favorable conditions - Haskovo hilly area.
The coincidence in the gradation of the single mountain units and whole areas with
respect to their suitability for construction and agriculture is due to the specificities
of the broadly developed height belts in them, with their inherent morphometric
characteristics, especially altitude, dismemberment and slopes. They are equally
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