ravine
A ravine is a landform that is narrower than a canyon and is often the product of streambank erosion.Portugal-Spain border, (Arroyo de Cuncos in Spanish).
Portugal
Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
does not recognise the border between Caia and Ribeira de Cuncos River deltas, since the beginning of the 1801 occupation of
Olivenza
Olivenza () or Olivença () is a town in southwestern Spain, near the Portuguese border, on a historically disputed section of the Portugal–Spain border. Its territory is administered by Spain as a municipality belonging to the province of Bad ...
by Spain. This territory, though under ''de facto'' Spanish occupation, remains a ''de jure'' part of Portugal, consequently no border is henceforth recognised in this area.Guadiana River /ref>
The Castle of Cuncos situated nearby dates from pre-Roman time (specifically, the Iron Age). Today is completely submerged under the man made Alqueva reservoir created by the
Alqueva dam
The Alqueva Dam is an arch dam and the centrepiece of the Alqueva Multipurpose Project. It impounds the River Guadiana, on the border of Beja and Évora Districts in south of Portugal. The dam takes its name from the town of Alqueva to its right ...
. In the area, ancient foundations and remains belonging to the era have been discovered.
It runs into the
Guadiana river
The Guadiana River (, also , , ), or Odiana, is an international river defining a long stretch of the Portugal-Spain border, separating Extremadura and Andalusia (Spain) from Alentejo and Algarve (Portugal). The river's basin extends from the e ...