The river Jalón is located in the northeast of Spain, and is one of the principal tributaries of the Ebro. It has a length of 224 kilometres (139 mi) and drains a basin of 9,338 square kilometres (3,605 sq mi). The flow rate in Calatayud is 20.8 cubic metres per second (730 cu ft/s), but is highly irregular due to the great range of Mediterranean rainfall patterns.

The Ebro is a river of the north and northeast of the Iberian Peninsula, in Spain. It rises in Cantabria and flows 930 kilometres (580 mi), almost entirely in an east-southeast direction. It flows into the Mediterranean Sea, forming a delta in the Province of Tarragona, in southern Catalonia. In the Iberian peninsula, it ranks second in length after the Tagus and second in discharge volume, and drainage basin, after the Douro. It is the longest river entirely within Spain; the other two mentioned flow into Portugal. It is also the second-longest river in the Mediterranean basin, after the Nile.