IMPORTANCE OF WATER CIRCULATION SYSTEM IN RAZIM-GOLOVITA LAKES. STATUS AND QUALITY OF ECOSYSTEMS

Petre Bretcan*, Elena Tuchiu**, Simona Bretcan***

* Valahia University of Targoviste, Department of Geography
** Director National Administration “Apele Române”
*** Faculty of Geography, University of Bucharest

Abstract

The Razim-Golovita lakes are situated in northwestern Dobrogea, south of the Danube Delta and on the coast of the Black Sea and it appeared and evolved in a former branched marine gulf, Halmyris. The anthropic intervention, after 1970, led to significant modifications of the water volumes accumulated in the lakes from the Razim-Golovita compartment and implicitly of all the morphometric parameters (water volume, maximum and average depth, etc.). They are slightly variable from one year to the next, or from one season to the next, being for short periods of time directly dependent on the management of the water resource and on the type of water uses. The hydrological balance of the lakes from the Razim-Sinoie lake complex is directly influenced by the connections with Sfântu Gheorghe branch, by the hydrographic basin and the climatic conditions (low quantities of precipitations and intense evaporation), to which we can add the drainage in the sea up to Portiţa (before 1970) and the construction of the spillway from Periboina etc. After 1970, because of the anthropic modifications, the hydrological balance substantially changed, new components being introduced in the equation of this balance (losses by irrigations) and concerning the present values, the relations from the previous equations were modified. The tendency of salinity variation is opposed to that of flow variation, the salinity decreasing visibly during the periods with high Danube waters and the other way round. At present, nitrogen and phosphorus are the main elements controlling the biological processes in the lake complex and implicitly the quality of the water environment, their dynamics being significant. If at the beginning of the salinity reduction period, an increase of the species diversity was noted, now in the lagoon there is a major misbalance characterized by a drastic biodiversity reduction.

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