Drainage basin in the context of "Black Sea"

The Tiber (/ˈtaɪbər/ TY-bər; Italian: Tevere [ˈteːvere]; Latin: Tiberis) is the third-longest river in Italy and the longest in Central Italy, rising in the Apennine Mountains in Emilia-Romagna and flowing 406 km (252 mi) through Tuscany, Umbria, and Lazio, where it is joined by the River Aniene, to the Tyrrhenian Sea, between Ostia and Fiumicino. It drains a basin estimated at 17,375 km (6,709 sq mi). The river has achieved lasting fame as the main watercourse of the city of Rome, which was founded on its eastern banks.

The river rises at Mount Fumaiolo in Central Italy and flows in a generally southerly direction past Perugia and Rome to meet the sea at Ostia. The Tiber has advanced significantly at its mouth, by about 3 km (2 mi), since Roman times, leaving the ancient port of Ostia Antica 6 kilometres (4 miles) inland. However, it does not form a proportional delta, owing to a strong north-flowing sea current close to the shore, due to the steep shelving of the coast, and to slow tectonic subsidence.

The East European Plain (also called the Russian Plain, or historically the Sarmatic Plain) is a vast interior plain extending east of the North European Plain, and comprising several plateaus stretching roughly from 25 degrees longitude eastward. It includes Volhynian-Podolian Upland on its westernmost fringe, the Central Russian Upland, and, on the eastern border, encompasses the Volga Upland. The plain includes also a series of major river basins such as the Dnieper Lowland, the Oka–Don Lowland, and the Volga Basin. At the southeastern point of the East European Plain are the Caucasus and Crimean mountain ranges. Together with the North European Plain (covering much of Belgium, the Netherlands, Denmark, Germany and Poland), and covering the Baltic states (Estonia, Latvia and Lithuania), European Russia, Belarus, Ukraine, Moldova, southeastern Romania, and, at its southernmost point, the Danubian Plain in Northern Bulgaria (including Ludogorie and Southern Dobruja), it constitutes the majority of the Great European Plain (European Plain), the greatest mountain-free part of the European landscape. The plain spans approximately 4,000,000 km (2,000,000 sq mi) and averages about 170 m (560 ft) in elevation. The highest point of the plain (480 metres (1,574.8 ft)) is in the Bugulma-Belebey Upland, in the Eastern part of the plain, in the elevated area by the Ural Mountains (priyralie).

The Dnieper or Dnepr (/(də)ˈniːpər/ (də-)NEE-pər), also called the Dnipro. is one of the major transboundary rivers of Europe, rising in the Valdai Hills near Smolensk, Russia, before flowing through Belarus and Ukraine to the Black Sea. Approximately 2,200 km (1,400 mi) long, with a drainage basin of 504,000 square kilometres (195,000 sq mi), it is the longest river of Ukraine and Belarus and the fourth-longest river in Europe, after the Volga, Danube, and Ural rivers.

In antiquity, the river was part of the Amber Road trade routes. During the Ruin in the later 17th century, the area was contested between the Polish–Lithuanian Commonwealth and the Russian Empire, dividing what is now Ukraine into areas described by its right and left banks. During the Soviet period, the river became noted for its major hydroelectric dams and large reservoirs. The 1986 Chernobyl disaster occurred on the Pripyat River, a tributary of the Dnieper, just upstream from its confluence with the Dnieper. The Dnieper is an important navigable waterway for the economy of Ukraine and is connected by the Dnieper–Bug Canal to other waterways in Europe. During the 2022 Russian invasion of Ukraine, certain segments of the river were made part of the defensive lines between territory controlled by the Russians and the Ukrainians.

A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge. The soils usually consist of clays, silts, sands, and gravels deposited during floods.

Because of regular flooding, floodplains frequently have high soil fertility since nutrients are deposited with the flood waters. This can encourage farming; some important agricultural regions, such as the Nile and Mississippi river basins, heavily exploit floodplains. Agricultural and urban regions have developed near or on floodplains to take advantage of the rich soil and freshwater. However, the risk of inundation has led to increasing efforts to control flooding.

A drainage divide, water divide, ridgeline, watershed, water parting or height of land is elevated terrain that separates neighboring drainage basins. On rugged land, the divide lies along topographical ridges, and may be in the form of a single range of hills or mountains, known as a dividing range. On flat terrain, especially where the ground is marshy, the divide may be difficult to discern.

A triple divide is a point, often a summit, where three drainage basins meet. A valley floor divide is a low drainage divide that runs across a valley, sometimes created by deposition or stream capture. Major divides separating rivers that drain to different seas or oceans are continental divides.

The Evrotas (Modern Greek: Ευρώτας) or Eurotas (Ancient Greek: Εὐρώτας) is the main river of Laconia and one of the major rivers of the Peloponnese, in Greece. The river's springs are located just northwest of the border between Laconia and Arcadia, at Skortsinos. The river is also fed by underwater springs at Pellana and by tributaries coursing down from Mt. Taygetos and Mt. Parnon, which flank the Evrotas Valley to the west and east, respectively. The river is 82 kilometres (51 mi) long, flowing in a north-south direction and emptying into the Laconian Gulf. Its drainage basin is 2,239 km (864 sq mi).