Tagus

The Tagus is the longest river in the Iberian Peninsula. It is a massive waterway that shapes the landscape of Spain and Portugal. The river's name comes from the Latin Tagus. Experts believe its name might come from an Indo-European word meaning 'to drip.' This river is vital for the millions of people living in its basin. It connects major cities and serves many human needs.

The river begins high in the mountains of mid-eastern Spain. Its source is at Fuente García in the municipality of Frías de Albarracín. This spot is in the Montes Universales at an elevation of 1,593 meters. The source sits between two peaks: Muela de San Juan and Cerro de San Felipe. From here, the water flows generally toward the west. It travels through many different lands before reaching the sea.

In Spain, the Tagus flows through four autonomous communities. These are Aragón, Castilla-La Mancha, Madrid, and Extremadura. It also passes through six different provinces. These provinces include Teruel, Guadalajara, Cuenca, Madrid, Toledo, and Cáceres. For a distance of 47 km, the river forms a border between Spain and Portugal. This specific stretch is called the "International Tagus." After this border, the river enters Portugal and moves through several traditional regions.

The Tagus basin is a very large area. It covers 803,000 square kilometers of land. This is the most populated basin in the entire Iberian Peninsula. More than ten million people live within this basin. This includes the huge Madrid metropolitan area and the Lisbon region. The basin also holds a massive amount of water. Its total reservoir capacity is about 14,000 cubic hectometers. Engineers use these reservoirs for five main tasks. They provide drinking water and irrigation for farms. They also produce electricity and provide cooling for nuclear power plants. They even divert water to the Segura River basin.

The river's water levels change based on the weather. This is called a hydrological regime. The amount of water depends on rain and snow in the mountains. Large floods usually happen between January and April. The highest flow often occurs in March when snow melts. The river is at its lowest between July and October. In September, the flow reaches its minimum. This makes the river's course very irregular. At Alcántara, the flow can drop from 500 cubic meters per second to only 25 cubic meters per second.

The Tagus has a very unusual end where it meets the ocean. Most rivers have a delta that spreads out widely. The Tagus has an inverted delta. This means it is wider at the start and narrows as it hits the sea. This happens because the river flows into the sea through a small opening in a valley. Because of sediment, the valley is now mostly filled in. The delta is about 40 km wide and 30 km long. However, its exit into the sea is only 10 km wide. This creates a large lagoon with shallow sand banks. These banks are uncovered during low tides.

Nature thrives along the banks of the Tagus. Many areas are protected by law to keep them safe. These include Alto Tajo Nature Park, Monfragüe National Park, and the Tagus Estuary Natural Reserve. Because some areas have few people, the wildlife is well preserved. Four endangered animal species live here. These are the Iberian lynx, the Spanish imperial eagle, the black stork, and the black vulture. The river also offers fun activities for people. You can practice whitewater canoeing in the Alto Tajo canyon. Other people enjoy flat water canoeing in various reservoirs.

History is deeply tied to this river. The city of Toledo is a major historical site. It was built on a hill about 100 m high. The city sits near a river bend called Torno del Tajo. This height helped protect the city from attacks in the past. The mouth of the river was also very important for trade. During the Late Middle Ages, it linked Northern Europe to the Mediterranean. Later, during the Renaissance, it was a main hub for the Portuguese Empire. This empire reached across America, Africa, and Asia.