| The Yesa reservoir, the
largest Pyrenean reservoir, was constructed in 1959 to supply water to new
irrigated areas in the Ebro Depression, NE Spain. It is filled from October to
May-June and then releases large quantities of water in the summer via the
Bardenas Canal. The results confirm that the frequency of floods downstream of
the dam decreased. The reduction mainly depends on two factors: i) the water
storage level, and ii) the season of the year. Floods are very well controlled
when the reservoir level is lower than 50%. Between 50 and 70%, only the highest
floods are controlled. Finally, the reservoir retains mainly autumn and spring
floods; most winter floods are released downstream to ensure the safety of the
dam.
Keywords: reservoir, flood control, flood seasonality, flood frequency,
river regime, Pyrenees |