River delta in the context of Ecology

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 Nile Delta (Arabic: دلتا النيل, Delta an-Nīl or simply الدلتا, ad-Delta) is the delta formed in Lower Egypt where the Nile River spreads out and drains into the Mediterranean Sea. It is one of the world's largest deltas. From Alexandria in the west to Port Said in the east; it covers 240 km (150 mi) of the Mediterranean coastline and is a rich agricultural region. From north to south the delta is approximately 160 km (100 mi) in length. The Delta begins from Cairo.

The Rhône (/roʊn/ ROHN, French: [ʁon] ; Occitan: Ròse; Arpitan: Rôno) is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and Southeastern France before discharging into the Mediterranean Sea (Gulf of Lion). At Arles, near its mouth, the river divides into the Great Rhône (French: le Grand Rhône; Occitan: Grand Ròse) and the Little Rhône (le Petit Rhône; Pichon Ròse). The resulting delta forms the Camargue region.

The river's source is the Rhône Glacier, at the eastern edge of the Swiss canton of Valais. The glacier is part of the Saint-Gotthard Massif, which gives rise to three other major rivers: the Reuss, Rhine and Ticino.

Veneto, officially the Region of Veneto, is one of the 20 regions of Italy, located in the north-east of the country. It is the 4th most populous region in Italy, with a population of 4,851,851 as of 2025. Venice is the region's capital while Verona is the largest city.

Veneto was part of the Roman Empire until the 5th century AD. Later, after a feudal period, it was part of the Republic of Venice until 1797. Venice ruled for centuries over one of the largest and richest maritime republics and trade empires in the world. After the Napoleonic Wars and the Congress of Vienna, the former Republic was combined with Lombardy and re-annexed to the Austrian Empire as the Kingdom of Lombardy–Venetia, until that was merged with the Kingdom of Italy in 1866, as a result of the Third Italian War of Independence and of a plebiscite.

The Persian Gulf, sometimes called the Arabian Gulf, is a mediterranean sea in West Asia. The body of water is an extension of the Arabian Sea and the larger Indian Ocean located between Iran and the Arabian Peninsula. It is connected to the Gulf of Oman in the east by the Strait of Hormuz. The river delta of the Shatt al-Arab forms the northwest shoreline.

The Persian Gulf has many fishing grounds, extensive reefs (mostly rocky, but also coral), and abundant pearl oysters; however, its ecology has been damaged by industrialization and oil spills.

The Maritsa, known in Greek as the Hebros and in Turkish as the Meriç, is a river that runs through the Balkans in Southeast Europe. With a length of 480 km (300 mi), it is the longest river that runs solely in the interior of the Balkan peninsula, and one of the largest in Europe by discharge. It flows through Bulgaria in its upper and middle reaches, while its lower course forms part of the border between Greece and Turkey. Its drainage area is about 53,000 km (20,000 sq mi), of which 66.2% is in Bulgaria, 27.5% in Turkey, and 6.3% in Greece. It is the main river of the historical region of Thrace, most of which lies in its drainage basin.

It has its origin in the Rila Mountains in Western Bulgaria, its source being the Marichini Lakes. The Maritsa flows east-southeast between the Balkan and Rhodope Mountains, past Plovdiv and Dimitrovgrad in Bulgaria to Edirne in Turkey. East of Svilengrad, Bulgaria, the river flows eastwards, forming the border between Bulgaria (on the north bank) and Greece (on the south bank), and then between Turkey and Greece. At Edirne, the river meets its two chief tributaries Tundzha and Arda, and flows through Turkish territory on both banks. It then turns towards the south and forms the border between Greece on the west bank and Turkey on the east bank all the way to the Aegean Sea, which it enters near Enez, forming a river delta. The upper Maritsa valley is a principal east–west route in Bulgaria. The unnavigable river is used for hydroelectric power generation and for irrigation.

The Nestos (Greek: Νέστος [ˈnes̠tos̠]) or the Mesta (Bulgarian: Ме́ста [ˈmɛstɐ]) is a river in Bulgaria and Greece. It rises in the Rila Mountains and flows into the Aegean Sea near the island of Thasos. It plunges down towering canyons toward the Aegean Sea through mostly metamorphic formations. At the end, the main stream spreads over the coastal plain of Chrysoupolis and expands as a deltaic system with freshwater lakes and ponds forming the Nestos delta. The length of the river is 230 km (140 mi), of which 126 km (78 mi) flow through Bulgaria and the rest in Greece. Its drainage area is 5,184 km (2,002 sq mi), of which 66% is in Bulgaria. It forms some gorges in Rila and Pirin. The longest gorge between Pirin to the west and the Rhodope Mountains to the east is the 25-km long Momina Klisura in Bulgaria.

The Mesta's longest tributary is the Dospat (or Despatis). The banks of the river are covered mainly by deciduous trees that extend into halfway between Bulgaria and Greece where it forms the modern boundary of Greek Macedonia and Thrace, as well as the boundary between the Kavala and the Xanthi regional units, having first crossed the Drama regional unit. The river later forms a delta to the north where swamplands, wetlands and a lagoon once existed except in the east.

The Danube Delta (Romanian: Delta Dunării, pronounced [ˈdelta ˈdunərij] ; Ukrainian: Дельта Дунаю, romanized: Del'ta Dunaju, pronounced [delʲˈtɑ dʊnɐˈju]) is the second largest river delta in Europe, after the Volga Delta, and is the best preserved on the continent. Occurring where the Danube River empties into the Black Sea, most of the Danube Delta lies in Romania (Tulcea County), with a small part located in Ukraine (Odesa Oblast). Its approximate surface area is 4,152 square kilometres (1,603 square miles), of which 3,446 km (1,331 sq mi) is in Romania. With the lagoons of Razim–Sinoe (1,015 km or 392 sq mi with 865 km or 334 sq mi water surface), located south of the main delta, the total area of the Danube Delta is 5,165 km (1,994 sq mi). The Razim–Sinoe lagoon complex is geologically and ecologically related to the delta proper; the combined territory is listed as a World Heritage Site.

The Gediz Delta is the river delta at the confluence of the Gediz River with the Gulf of İzmir, in İzmir Province in western Turkey. It is a 14,900 ha area of land that occupies coastal parts of Foça, Menemen, and Çiğli districts. It is one of the largest areas of coastal wetlands in Turkeyand has a biodiversity of plants and birds. It is a Ramsar site since 1998 and an Important Bird Area since 2000. It is 26 km from İzmir city center.

A river island is any exposed landmass surrounded by river water. Properly defined, it excludes shoals between seasonally varying flows and may exclude semi-coastal islands in river deltas such as Marajó.

These islands result from changes in the course of a river. Such changes may be caused by interactions with a tributary, or by the opposing fluvial actions of deposition and/or erosion that form a natural cut and meander. Nascent vegetation-free shoals and mudflats may dissipate and shift or build up into such islands through deposition; the process may be assisted through artificial reinforcement or natural factors, such as reeds, palms, evergreen trees or willows, that act as obstacles or erosion barriers, so that water flows around them. Islands may be small or large, covering many square kilometers, examples of which are given below.

In physical geography and hydrology, a channel is a landform on which a relatively narrow body of water is situated, such as a river, river delta or strait. While channel typically refers to a natural formation, the cognate term canal denotes a similar artificial structure.

Channels are important for the functionality of ports and other bodies of water used for navigability for shipping. Naturally, channels will change their depth and capacity due to erosion and deposition processes. Humans maintain navigable channels by dredging and other engineering processes.

River bifurcation (from Latin: furca, fork) occurs when a river (a bifurcating river) flowing in a single channel separates into two or more separate streams (called distributaries) which then continue downstream. Some rivers form complex networks of distributaries, typically in their deltas. If the streams eventually merge again or empty into the same body of water, then the bifurcation forms a river island.

River bifurcation may be temporary or semi-permanent, depending on the strength of the material that is dividing the two distributaries. For example, a mid-stream island of soil or silt in a delta is most likely temporary, due to low material strength. A location where a river divides around a rock fin, e.g. a volcanically formed dike, or a mountain, may be more lasting as a result of higher material strength and resistance to weathering and erosion. A bifurcation may also be man-made, for example when two streams are separated by a long bridge pier.

The Karakalpaks, or Qaraqalpaqs (/ˈkærəkɑːlpɑːks, -pæks/ ; Karakalpak: Qaraqalpaqlar, Қарақалпақлар, قاراقلپقلر), are a Turkic ethnic group native to Karakalpakstan in Northwestern Uzbekistan. During the 18th century, they settled in the lower reaches of the Amu Darya and in the (former) delta of Amu Darya on the southern shore of the Aral Sea. The name Karakalpak comes from two words: qara meaning 'black' and qalpaq meaning 'hat'. The Karakalpaks number nearly 871,970 worldwide, out of which about 726,000 live in the Karakalpakstan region of Uzbekistan.

Khwarazm or Chorasmia is a large oasis region on the Amu Darya river delta in western Central Asia, bordered on the north by the (former) Aral Sea, on the east by the Kyzylkum Desert, on the south by the Karakum Desert, and on the west by the Ustyurt Plateau. It was the center of the Iranian Khwarezmian civilization until the 9th century, when Turkic tribes moved into and ruled the lands. A series of kingdoms such as the Afrighid dynasty and the Anushtegin dynasty, whose capitals were (among others) Kath, Gurganj (now Konye-Urgench) and—from the 16th century on—Khiva. Today Khwarazm belongs partly to Uzbekistan and partly to Turkmenistan.

The Vistula (/ˈvɪstjʊlə/; Polish: Wisła [ˈviswa] ) is the longest river in Poland and the ninth-longest in Europe, at 1,047 kilometres (651 miles) in length. Its drainage basin, extending into three other countries apart from Poland, covers 193,960 km (74,890 sq mi), of which 168,868 km (65,200 sq mi) is in Poland.

The Vistula rises at Barania Góra in the south of Poland, 1,220 meters (4,000 ft) above sea level in the Silesian Beskids (western part of Carpathian Mountains), where it begins with the White Little Vistula (Biała Wisełka) and the Black Little Vistula (Czarna Wisełka). It flows through Poland's largest cities, including Kraków, Sandomierz, Warsaw, Płock, Włocławek, Toruń, Bydgoszcz, Świecie, Grudziądz, Tczew and Gdańsk. It empties into the Vistula Lagoon (Zalew Wiślany) or directly into the Gdańsk Bay of the Baltic Sea with a delta of six main branches (Leniwka, Przekop, Śmiała Wisła, Martwa Wisła, Nogat and Szkarpawa).

The Camargue (/kæˈmɑːrɡ/, also UK: /kəˈ-/, US: /kɑːˈ-/, French: [kamaʁɡ]; Provençal: Camarga) is a coastal region in southern France located south of the city of Arles, between the Mediterranean Sea and the two arms of the Rhône river delta. The eastern arm is called the Grand Rhône; the western is the Petit Rhône.

Administratively, it lies within the department of Bouches-du-Rhône (‘Mouths of the Rhône’); it spans portions of the communes of Arles, Saintes-Maries-de-la-Mer and Port-Saint-Louis-du-Rhône. A further expanse of marshy plain, known as the "Petite Camargue" (Little Camargue; Occitan: Pichon Camarga), just to the west of the "Petit Rhône", lies within the department of Gard.