scholarly journals Characterization of the Karst water regime in the Danube catchment area (Bulgaria)

2016 ◽  
Vol 96 (1) ◽  
pp. 11-25 ◽  
Author(s):  
Evelina Damyanova ◽  
Aleksey Benderev
Keyword(s):  
Black Sea ◽  
Catchment Area ◽  
Monitoring Network ◽  
Danube River ◽  
The Black Sea ◽  
Karst Water ◽  
Karst Springs ◽  
The Danube River ◽  
Danube Catchment

The purpose of study is to estimate the role of karst springs in the formation of the flow of the Bulgarian rivers that are right tributaries of the Danube River. The study area includes the region from the Danube River to the main ridge of the Balkan (Stara Planina), representing a major water divide that separates the Black Sea catchment area from the Aegean one. The eastern border represents the watershed between the Danube and the Black Sea hydrological zones. From a geological point of view, the northern part of the area is located on the Moesian platform and the southern part belongs to the Fore Balkan and Balkan areas where various types of rocks of different geologic age outcrop. In some of them, there are conditions for the formation of karst water. In the northern part of the area they form distinct aquifers that gradually sink to the north; this is so called "platform" type of karst. In the southern mountainous part there are numerous karst basins. The most significant of karst springs are included in the national groundwater monitoring network. The hydrographs of karst springs are analyzed in view of the specific features of karstification. To classify the studied springs with respect to their regime, several indicators are used. Furthermore, the role of karst waters in the river runoff of the Bulgarian tributaries of the Danube River is assessed.

The Pliocene deposits of the Black Sea Shelf east of the Danube River Delta

2020 ◽  
pp. SP505-2019-102
Author(s):  
Petro F. Gozhik ◽  
Valery E. Rokitsky
Keyword(s):  
Black Sea ◽  
River Delta ◽  
Danube River ◽  
Core Material ◽  
The Black Sea ◽  
Danube Delta ◽  
The Danube River ◽  
Continental Deposits ◽  
Circular Current ◽  
The One

AbstractThis paper provides analysis of the published materials on the occurrences of the Dacian and Cimmerian molluscs in the Danube River valley as well as the results of Pliocene sediments study based on core material of the boreholes drilled at the Black Sea Shelf east of the Danube River Delta.In the early Pontian time, the Dacian Basin was a large sub-basin of Paratethys which, due to an abrupt drop in sea level, separated into the Euxinian, Dacian and Caspian basins. At the end of the Bosphorus time, the discharge of the Dacian Basin waters into the Euxinian Basin formed a wide valley from the Galati-Reni region to the east through the Galati gateway. During the Cimmerian transgression, a vast bay existed on the site of the modern Danube Delta, from which mutual migrations of the Dacian and Cimmerian molluscs took place along the runoff valley. The cessation of runoff occurred during the regressive phase of the Late Cimmerian. The rhythmically bedded thick strata originated during the existence of the runoff valley. These strata were identified as the Pridanubian Formation (Suite). The cryptogenic form of Tulotoma Tulotoma (=Viviparus) ovidii nasonis (Bogachev) is characteristic of the lower and middle parts of the suite. The presence of the Dacian and Cimmerian molluscs in this suite became the basis for the correlation of sediments of the Dacian and Cimmerian regional stages. The Duabian molluscs were registered in the Cimmerian deposits of the Transcaucasus (the Duabian layers), Priazovye and the Kerch–Taman region. The migration of these molluscs took place during the regressive phases due to the circular current in the Euxinian Basin similar to the one existing in the Black Sea today.The Pliocene formation contains marine and continental deposits of the Lower and Upper Pliocene, which are represented by the Pridanubian Formation (Lower and Upper), Cimmerian deposits (non-subdivided Lower and Middle Cimmerian), Lower Kujalnician deposits, Upper Poration deposits, complex of red-coloured palaeosols (the Upper Miocene–Lower Pliocene non-subdivided).The formation of the Pliocene sediments on the Black Sea Shelf, east of the Danube Delta, was controlled by the inter-basin connectivity of the Eastern Paratethys.

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