linguistic:voice_change, structural:summarization
Hydrology

The coastal water dynamics are determined by the asymmetric coasts and the inflow of the Mediterranean seawater through the Straits of Otranto and further on along the eastern coast. The smooth Italian coast (with very few protrusions and no major islands) allows the Western Adriatic Current to flow smoothly, which is composed of the relatively freshwater mass on the surface and the cold and dense water mass at the bottom. The coastal currents on the opposite shore are far more complex owing to the jagged shoreline, several large islands and the proximity of the Dinaric Alps to the shore. The last produces significant temperature variations between the sea and the hinterland, which leads to the creation of local jets. The tidal movement is normally slight, usually remaining below 30 centimetres (12 in). The amphidromic point is at the mid-width east of Ancona.

The normal tide levels are known to increase significantly in a conducive environment, leading to coastal flooding; this phenomenon is most famously known in Italy—especially Venice—as acqua alta. Such tides can exceed normal levels by more than 140 centimetres (55 in), with the highest tide level of 194 centimetres (76 in) observed on 4 November 1966. Such flooding is caused by a combination of factors, including the alignment of the Sun and Moon, meteorological factors such as sirocco related storm surges, and the basin's geometric shape (which amplifies or reduces the astronomical component). Moreover, the Adriatic's long and narrow rectangular shape is the source of an oscillating water motion (French: seiche) along the basin's minor axis. Finally, Venice is increasingly vulnerable to flooding due to coastal area soil subsidence. Such unusually high tides resulting in flooding have also been observed elsewhere in the Adriatic Sea, and have been recorded in recent years in the towns of Koper, Zadar and Šibenik as well.

It is estimated that the Adriatic's entire volume is exchanged through the Strait of Otranto in 3.4±0.4 years, a comparatively short period. (For instance, approximately 500 years are necessary to exchange all the Black Sea 's water.) This short period is particularly important as the rivers flowing into the Adriatic discharge up to 5,700 cubic metres per second (200,000 cu ft/s). This rate of discharge amounts to 0.5% of the total Adriatic Sea volume, or a 1.3-metre (4 ft 3 in) layer of water each year. The greatest portion of the discharge from any single river comes from the Po (28%), with an average discharge from it alone of 1,569 cubic metres per second (55,400 cu ft/s). In terms of the annual total discharge into the entire Mediterranean Sea, the Po is ranked second, followed by the Neretva and Drin, which rank as third and fourth. Another significant contributor of freshwater to the Adriatic is the submarine groundwater discharge through submarine springs (Croatian: vrulja); it is estimated to comprise 29% of the total water flux into the Adriatic. The submarine springs include thermal springs, discovered offshore near the town of Izola. The thermal spring water is rich with hydrogen sulfide, has a temperature of 22 to 29.6 °C (71.6 to 85.3 °F), and has enabled the development of specific ecosystems. The inflow of freshwater, representing a third of the freshwater volume flowing into the Mediterranean, makes the Adriatic a dilution basin for the Mediterranean Sea. The Middle and South Adriatic Gyres (SAG), are significant cyclonic circulation features, with the former being intermittent and the latter permanent. The SAG measures 150 kilometres (93 miles) in diameter. It contributes to the flow of bottom water from the Adriatic to the Levantine Basin through the Ionian Sea. Through that process, the Adriatic Sea produces most of the East Mediterranean deep water.