Groundwater Systems
These shallow waters occur in porous materials like sand and gravel and are common near rivers and floodplains.
Phreatic groundwaters.
The two major drainage basins in Bulgaria’s river system flow into these seas.
The Black Sea and the Aegean Sea.
Most of Bulgaria’s lakes belong to these types.
Coastal lagoons/limans and glacial lakes.
This Bulgarian lowland region is known for its shallow phreatic groundwater.
The Upper Thracian Lowland.
Which part of Bulgaria is richer in rivers, and what hydrological factor explains this?
Southern Bulgaria, due to Mediterranean climate influence and winter rainfall.
The majority of Bulgaria’s glacial lakes are located in which two mountain ranges?
Rila and Pirin
Found in limestone and cave regions, these groundwaters have high discharge and excellent quality.
Karst groundwaters.
Explain the cause of Bulgaria’s alternating high-water and low-water periods throughout the year.
High water from snowmelt or winter rains; low water from summer heat and evaporation.
This city’s lake forms Bulgaria’s largest lake basin.
Varna
Name two Bulgarian sites famous for karst springs
Devnenski Springs and Kleptuza (in Velingrad).
Name two natural factors that determine river regime in Bulgaria.
Precipitation, temperature, and climate zone (Mediterranean vs. temperate continental).
This lake near the Black Sea is the largest in Bulgaria.
Lake Burgas
Why are karst groundwaters both highly valuable and environmentally vulnerable?
Because their high permeability gives large discharge but allows pollutants to spread quickly
When and what causes the high-water period that occurs in southern Bulgaria?
In winter, caused by Mediterranean and Temperate continental hydrological areas.
Why have many coastal lakes and lagoons dried up over time?
Due to drainage, sediment buildup, land changes