Water Qualitative Parameters of Fluviatile Limans Located in the South - West of Dobrogea (Romania)

The fluviatile limans in the south-west of Dobrogea are the most characteristic forms of this type, with an exclusive development on the territory of Romania. In time, they were interpreted as fluvio-maritime limans or even as fluvio-lacustrine limans. As a result of the fact that they are situated close to the Danube, bordering one of the driest regions of Romania, they have had diverse usage since ancient times. Because the fluviatile limans in Dobrogea are mostly used in pisciculture, the water qualitative parameters have to be monitored permanently. They also have a role in attenuating floods, acting as a tampon against flash floods. Consequently, they have a special local importance even today, feeding as much of the population as possible (directly or indirectly). From a geomorphological point of view the fluviatile limans in Dobogea were formed as a result of the withdrawal of the Romanian (Levantine). The decrease in depth may cause the flood waves to pass over the dams. In this case, the periodical drainage of lake cuvettes is required. The physical parameters of water (depth, transparency and temperature) as well as the chemical parameters (pH, dissolved oxygen, nitrates, nitrites, phosphates and the Ca/Mg ratio) have been analyzed. From an ecological viewpoint, the fluviatile limans in the south-west of Dobrogea are suitable for fish breeding and for developing an adequate lacustrine life

TYPOLOGY OF LARGE DAMS. A REVIEW

The dams represent hydrotechnical constructions meant to ensure a judicious use of water resources. The international literature is extremely rich in data regarding the large dams on Earth. In this context, a hierarchy of the main dams is attempted and the role they play in the economic development of the regions they were built in is underlined. The largest dams are built on the big rivers in Asia, North America, South America and Africa. The reservoirs have multiple roles: electricity production, drinking or industrial water supply, irrigations, recreation, etc. High costs and land fragility do not allow the construction of dams in the places most affected by drought or flood. This is why they are usually built in mountainous areas, at great distance from the populated centres. On the Romanian territory, there are 246 large dams, built in the hydrographical basins of Siret, Olt, Arges, Somes, etc. The largest rivers on Earth, by discharge, (Amazon and Zair) do not also include the largest dams because the landform and the type of flow have not allowed such constructions