Part 5 (1/2)
The western portion is lower and more dissected; in the east it becomes regular but somewhat higher, better resembling a plateau. Bulgarians name local areas within it, but they do not name the region as a whole.
It is a fertile area with undulating hills and is the granary of the country.
The southern edge of the Danubian plateau blends into the foothills of the Stara Planina, the Bulgarian extension of the Carpathian Mountains.
The Carpathians resemble a reversed S as they run eastward from Czechoslovakia across the northern portion of Romania, swinging southward to the middle of that country, where they run westward and cross Romania as the Transylvanian Alps. At a famous gorge of the Danube River known as the Iron Gate, which forms part of the Romania-Yugoslavia border, the Carpathians again sweep eastward, becoming Bulgaria's Stara Planina range.
Considered in its local context, the Stara Planina originates at the Timok Valley in Yugoslavia, continues southeastward as it becomes the northern boundary of the Sofia Basin, and then turns more directly eastward to terminate at Cape Emine on the Black Sea. It is some 370 miles in length, and some twelve to thirty miles in width. It retains its height well into the central part of the country, where Botev Peak, its highest point, rises to about 7,800 feet. The range is still apparent until its rocky cliffs fall into the Black Sea. Over most of its length, its ridge is the divide between drainage to the Danube River and to the Aegean Sea. In the east small areas drain directly to the Black Sea.
Sometimes considered a part of the foothills of the Stara Planina, but separated from the main range by a long geological trench that contains the Valley of Roses, is the Sredna Gora (Middle Forest). The Sredna Gora is a ridge running almost precisely east to west, about 100 miles long.
Its elevations run to only a little more than 5,000 feet, but it is narrow and achieves an impression of greater height.
The southern slopes of the Stara Planina and the Sredna Gora give way to the Thracian Plain. The plain is roughly triangular in shape, originating at a point east of the mountains that ring the Sofia Basin and broadening as it proceeds eastward to the Black Sea. It encompa.s.ses the Maritsa River basin and the lowlands that extend from it to the Black Sea. As is the case with the Danubian plateau, a great deal of this area is not a plain in strict terms. Most of its terrain is moderate enough to allow cultivation, but there are variations greater than those of a typical plain.
[Ill.u.s.tration: _Figure 2. Topography of Bulgaria_]
The Rodopi occupies the area between the Thracian Plain and the Greek border. This range is commonly described as including the Rila mountain range south of Sophia and the Pirin range in the southwestern corner of the country. As such, the Rodopi is the most outstanding topographic feature, not only of the country, but also of the entire Balkan Peninsula. The Rila contains Mount Musala--called Mount Stalin for a few years--whose 9,500-foot peak is the highest in the Balkans. About a dozen other peaks in the Rila are over 9,000 feet. They feature a few bare rocks and remote lakes above the tree line, but the lower peaks are covered with Alpine meadows, and the general aspect of the range is one of green beauty.
The Vitosha range is an outlier of the Rila. A symmetrical, 7,500-foot high, isolated peak in the range is a landmark on the outskirts of Sofia. Snow covers its conical summit most of the year, and its steep sides are forested.
The Pirin is characterized by rocky peaks and stony slopes. An impression of the landscape is provided by a local legend, which says that when the earth was being created G.o.d was flying over the peninsula with a bag of huge boulders. The rocks were too heavy for the bag, and it broke over southwestern Bulgaria.
Some Bulgarian geographers refer to the western Rodopi and the Pirin as the Thracian-Macedonian ma.s.sif. In this context, the Rodopi includes only the mountains south of the Maritsa River basin. There is some basis for such a division. The Rila is largely volcanic in origin. The Pirin was formed at a different time by fracturing of the earth's crust. The uplands east of the Maritsa River are not of the same stature as the major ranges.
Sizable areas in the western and central Stara Planina and smaller areas in the Pirin and in Dobrudzha have extensive layers of limestone. There are some 2,000 caves in these deposits. The public has become more interested in the caves during the past three or four decades, but only about 400 of them have been completely explored and charted.
To the east of the higher Rodopi and east of the Maritsa River are the Sakar and Strandzha mountains. They extend the length of the Rodopi along the Turkish border to the Black Sea but are themselves comparatively insignificant. At one point they have a spot elevation of about 2,800 feet, but they rarely exceed 1,500 feet elsewhere.
Formation of the Balkan landma.s.ses involved a number of earth crust foldings and volcanic actions that either dammed rivers or forced them into new courses. The flat basins that occur throughout the country were created when river waters receded from the temporary lakes that existed while the rivers were cutting their new channels. The largest of these is the Sofia Basin, which includes the city and the area about fifteen miles wide and sixty miles long to its northwest and southeast.
Other valleys between the Stara Planina and the Sredna Gora ranges contain a series of smaller basins, and similar ones occur at intervals in the valleys of a number of the larger rivers.
Drainage
From a drainage standpoint, the country is divided into two nearly equal parts. The slightly larger one drains to the Black Sea, the other to the Aegean. The northern watershed of the Stara Planina, all of the Danubian plateau, and the thirty to fifty miles inland from the coastline drain to the Black Sea. The Thracian Plain and most of the higher lands of the south and southwest drain to the Aegean Sea. Although only the Danube is navigable, many of the other rivers and streams have a high potential for the production of hydroelectric power and are sources of irrigation water. Many are already being exploited.
Insignificant when compared with the watersheds that drain to the seas, about 125 square miles of the country drain into a few small salt lakes that have no outflowing water. The largest such lake has a surface area of 2.5 square miles.
By far the greater part of the country that drains to the Black Sea does so through the Danube. Most of its major tributaries in the country (from west to east, the Ogosta, Iskur, Vit, Osum, Yantra, and Lom) carry more water than do the combination of the Provadiyska, Kamchiya, Fakiyska, and Veleka rivers, all of which flow directly into the Black Sea. Of the Danube's Bulgarian tributaries, all but the Iskur rise in the Stara Planina. The Iskur rises in the Rila and flows northward through a narrow basin. Territory not far from the river on both sides of it drains in the opposite direction, to the south. The Iskur pa.s.ses through Sofia's eastern suburbs and cuts a valley through the Stara Planina on its way to join the Danube.
The Iskur and the other of the Danube's north-flowing tributaries have cut deep valleys through the Danubian plateau. The eastern banks tend to rise sharply from the rivers; the western parts of the valleys may have broad fields with alluvial soils. The peculiar, though consistent, pattern is caused by forces resulting from the earth's rotation; these forces give the water a motion that tends to undercut the right banks of the streams. Some of these rivers are sizable streams, but the Danube gets only a little more than 4 percent of its total volume from its Bulgarian tributaries. As it flows along the northern border, the Danube averages one to 1.5 miles in width. Its highest water levels are usually reached during June floods, and in normal seasons it is frozen over for about forty days.
Several major rivers flow directly to the Aegean Sea, although the Maritsa with its tributaries is by far the largest. The Maritsa drains all of the western Thracian Plain, all of the Sredna Gora, the southern slopes of the Stara Planina, and the northern slopes of the eastern Rodopi. Other than the Maritsa, the Struma in the west and the Mesta (which separates the Pirin from the main Rodopi ranges) are the two largest of the rivers that rise in Bulgaria and flow to the Aegean. Most of these streams fall swiftly from the mountains and have cut deep, scenic gorges. The Struma and Mesta reach the sea through Greece. The Maritsa forms most of the Greek-Turkish border after it leaves Bulgaria.
About 3,750 square miles of agricultural land have access to irrigation waters. Dams provide the water for about one-half of the acreage; diversions from rivers and streams serve about one-third; and water pumped from the ground and from streams accounts for the remainder.
Of the dams, ninety-two are termed large state dams. Their combined capacity is three times that of some 2,000 smaller dams. The sources of four large rivers--the Maritsa, Iskur, Mesta, and Rilska (a major tributary of the Struma)--are within a few miles of each other in the high Rila. Water from the upper courses of these and several other streams supplies the Sofia area with both water and electricity, and they have a potential for further development. There are major dams on the Tundzha, Iskur, Rositsa, and Struma rivers. The Danube is too ma.s.sive a stream to harness, and damming the Maritsa along most of its course would flood too much valuable land. The rivers flowing north across the Danubian plateau also tend to be overly difficult to use in the areas where they are most needed.
The Vucha River, flowing from the Rodopi into the Maritsa River, is often used to ill.u.s.trate how rivers have been effectively harnessed to provide a variety of benefits. Its cascade system of hydroelectric development employs six dams having the capacity to generate over 600,000 kilowatts of electricity. The water they back up serves the munic.i.p.al water systems in Plovdiv and a number of other towns in its vicinity, and the dams provide irrigation water for nearly 250,000 acres of cropland. The reservoirs themselves are being developed as recreational areas and mountain resorts.
Where a stream is difficult to dam or to divert, water is pumped from it. This has been feasible only since about 1950, when low-cost diesel engines and sufficient hydroelectric power became available from newly constructed dams on other streams. About eighty-five huge pumping stations have been set up along the Danube River, which furnishes about three-quarters of the water acquired by this method; and in 1970 there were about 1,200 lesser stations operating on smaller streams, most of them on the Thracian Plain.