5. The River Tagus

 

Tagus takes the long way to the sea

Introduction.

This is not a 'personal experience' river. In fact I knew nothing about it until realising how interesting it is. At 600+ miles, the River Tagus (Tajo in Spain, Tejo in Portugal) is the longest river of the Iberian peninsula. It arises in the mountains 90 miles from the east coast and only 60 miles east of Madrid. Its source is marked by a monument Nacimiento de Rio Tajo (Birth of the River Tagus) in the Sierra de Albarracin mountains - a small range with a highest point of 1600 metres. This may be only half the height of the peak of the Pyrenees, but is almost double the height of Englands highest peak, and is part of some of the most untamed terrain in the peninsula. Such is the watershed that instead of pursuing a short course to the Mediterranean, it wends its way tortuously six times further to empty into the Atlantic Ocean at Lisbon, officially 636 miles away. Thus the river nearly bisects Iberia, and does indeed bisect Portugal.

The Tagus initially travels south west, and for many miles marks the border between the regions ('autonomous communities' in todayspeak) of Aragon and Castile la Mancha. At the ancient city of Aranjuez it has a confluence with the river Jarama, one of its largest tributaries. The Jarama itself flows north to south, passing Madrid and the site of a fierce battle during the Spanish Civil war. Toledo is another city on the Tagus in the centre of Spain, some 50 miles south west of Madrid. The old city nestles in a large U-shaped bend in the river. It was famed for its cosmopolitanism until the ejection of the Jews in 1492 and Muslims in 1502.

West of Toledo the river is subject to major water management programmes with creations of dams and reservoirs providing vital supplies for domestic and agricultural use. The largest of these is Embalise de Alcantara - the dam at Alcantara - to the east of the border with Portugal. The dam is an enormous structure, completed in the late 1960s, creating Europe's second largest reservoir. As it continues westwards the river forms part of the border with Portugal, and flows through Portugal until it reaches the Bay of Biscay as a broad estuary that has made Lisbon such an economic and cultural hub over many centuries. Throughout its course the Tagus flows through spectacular scenery, historic towns and multiple precious sites of nature reserves, wildlife parks and wetlands.

The Future. With climate change, and increasing fears regarding the 'desertification' of southern Spain, the existence of the Tagus will be even more under pressure, as other smaller rivers become impermanent. At the other extreme the river, particularly the lower Tagus, is vulnerable to flooding and the extremities of climate change pose a different threat - exemplified by the catastrophic 2024 floods that affected the Valencia and Castile la Mancha areas. In 1979 central Portugal was badly damaged by flooding from the lower Tagus. Challenges posed by climatic extremes will be difficult to manage.

Spain Portugal Border. I've often wondered about this border. Looking generally at the large rectangle that comprises the Iberian peninsula below the Pyrenees, it seems curious to have another rectangle neatly slotted into its western and southern limits. It is a natural border, rather than the strict demarcation lines that separate, say, north from south Korea; or in the Middle East, or many of the states and provinces of North America. It seems that Portugal emerged as a sovereign nation in the 12th century CE with the Treaty of Zamora in 1143. For 150 years disputes and conflicts led to many adjustments, but pretty much what continues today was settled by the Treaty of Alcañices in 1297. The 750 miles border (to which the Tagus contributes a mere 30 or so miles) remains almost unchanged since- interrupted only by Spanish occupation 1580-1640 - making it one of Europe's oldest boundaries.