Which rivers flow through Athens, and why are they often dry or small?

The two primary rivers that traverse Athens are the Kifisós River, which flows through the western half of the city, and the Ilisós River, which crosses the eastern half.1

These rivers are often dry or reduced to a mere trickle, particularly during the summer months. This condition is largely due to the city's geographic setting within a mountain-girt, arid basin. The surrounding mountains—including Párnis, Pentelicus, Hymettos, and Aigáleon—contribute to the region's overall aridity. Additionally, heavy rains that pour off these denuded mountains can cause sudden, intense flooding, which has necessitated the implementation of modern sewer systems and flood control measures.12