Dam removals reignite debate on flood control in Spain

Dam removals reignite debate on flood control

How much responsibility do removed weirs bear for the severity of a flood? This question arises across Spain whenever violent storms hit the Mediterranean coast, yet answers remain divided. At the center of this clash are hydraulic works inherited from the Franco era—such as the Plan Sur, which diverted the Turia river away from Valencia—against recent demolitions of small weirs driven by environmental standards. Proponents of dams argue they regulate flow and curb floods; opponents counter that most did not retain water, serving only to divert it for irrigation or mills.

What is an azud and why remove it?

An *azud* (small weir) is not a dam. It is a low barrier that diverts part of the flow into an irrigation channel or millrace, historically used for watering crops and powering mills. It does not significantly store water. This technical argument supports demolition: when rivers swell, channels close and water overflows without meaningful retention. Conversely, critics note that the surface area behind weirs increases infiltration, leaving drier land afterward.

This debate is longstanding. Some claim historical engineers prioritized human needs over nature, while modern ones reverse this priority. The underlying accusation—that demolitions stem from ideology rather than technical necessity—lacks documentary proof in available materials. However, official maps listing demolished weirs and dams with dates are publicly accessible.

The Turia Plan Sur as evidence

Valencia city suffered minimal damage during the latest major storm, not by chance. The Plan Sur, which rerouted the Turia south of the city, serves as proof that hydraulic engineering works when implemented. While the urban core remained protected, surrounding areas did not. This asymmetry—safe city center versus flooded periphery—fuels comparisons with neglected projects elsewhere.

No dike network exists at the headwaters of the Poyo ravine, nor is there canalization downstream—the zones hardest hit. The lingering question is whether such works would have made a difference or if no dike could contain a storm of that magnitude. Available data does not resolve this doubt, nor do proponents provide calculations.

The timeline battle: who warned and when?

Public alerts arrived hours after initial warnings. Mobile alerts sounded at 20:00, when people were already trapped. The regional emergency coordination center issued first alerts at 20:10. Earlier, the regional president stated on social media that the storm would ease after 18:00. Emergency management falls under regional authority, drawing sharp criticism: warnings came too late.

Criticism also targets the central government for removing hydraulic infrastructure. Claims that more dams and weirs were destroyed than in the entire EU lack verifiable sources. Comparisons with the 1957 flood and the 1879 southeast event remind us floods are not new but do not clarify if removed structures would have altered outcomes.

The abolished emergency unit

The Generalitat created an emergency unit in February 2023 and abolished it in November of the same year, four months later. Its dissolution is frequently cited to criticize regional management. Defenders called it a patronage scheme with two hand-picked appointees; critics argue dismantling coordination structures before a storm is hard to justify.

The result is a nation debating responsibilities while counting victims. A lack of official data on what was demolished, when, and based on which technical reports allows each side to choose its scapegoat. This cycle has persisted since 1957.

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The next flood will raise the same questions again. And we will likely answer them with hydraulic amateurism.