A. Rivers and Lakes

The principal river draining Bulgaria is the Danube, which has among its Bulgarian tributaries the Iskŭr (about 370 km/230 mi long) and the Yantra (about 290 km/180 mi long). Other important rivers are the Kamchiya (about 180 km/110 mi long), which empties into the Black Sea, and in the south-west, the Struma and Mesta, which flow south to the Aegean Sea.

B. Climate

Most of Bulgaria has a continental climate, with cold winters and hot summers. The climate in general is more severe than in other European areas of the same latitudes, and the average annual temperature range is greater than that of neighbouring countries. Severe droughts, frosts, wind, and hail frequently damage crops. A Mediterranean climate, with dry summers and mild, humid winters, prevails in the valley of the south-western Rhodope Mountains; the northern limit of the climatic zone is the Balkan Mountains.

The average annual temperature is about 12.8° C (55° F). The average rainfall is about 635 mm (25 in) per year, ranging from a low of around 200 mm (8 in) in the north-east, to a high of 1,905 mm (75 in) in the Rila Mountains. The wettest period is early summer in most of the country and autumn or winter in the southern valleys.

C. Natural Resources

The main resources of Bulgaria are agricultural. The country also has a wealth of metallic and non-metallic minerals, mainly iron ore and coal. Other mineral reserves are small, but some deposits, particularly those of manganese and oil, are valuable.

D. Plants and Animals

Approximately one third of Bulgaria is forested, and half this area supports tall trees suitable for timber. About 30 per cent of the timber trees are conifers. The Balkan Mountains and their foothills support forests of various trees. Conifers, beech, and oak are found in the timber zone of the Rhodope Mountains and their western extensions. Wild animals are confined to the mountainous south-western portion of the country, where bear, wolf, elk, fox, and wildcat are found.

E. Soils

Soil types vary considerably. Some tablelands have fertile black and grey soils, high in humus content and well suited for growing grain. The Thracian Plain contains brown, loamy soils that are fertile and adapted to diversified cultivation. Deforestation and inadequate soil-conservation practices have caused gradual deterioration of several fertile areas.

F. Environmental Concerns

Bulgaria’s industrial economy has had a negative impact on the environmental health of the country. Virtually all of the middle and lower reaches of the major rivers are polluted by industrial centres that discharge detergents, heavy metals, nitrates, oils, and raw sewage. Water treatment facilities for industrial and municipal wastes are inadequate or non-existent. Two of the largest industrial cities, Varna and Burgas, are located on the Black Sea coast, and the water pollution generated by these centres has threatened the area’s tourist industry. Uncontrolled mining operations and environmentally insensitive practices also contribute to soil contamination. Air pollution, from motor vehicles and industrial emissions, is severe, leading to acid rain and the defoliation of a large portion of Bulgaria’s forests. During the early 1990s the European Community (now the European Union (EU)) granted Bulgaria aid money for the improvement of environmental and nuclear safety.

The government has ratified international environmental agreements pertaining to air pollution, Antarctic environmental protocol, Antarctic treaty, biodiversity, climate change, endangered species, environmental modification, hazardous wastes, law of the sea, nuclear test ban, ozone layer protection, ship pollution, and wetlands.