Interceptor Channel

By project ClimateGO

Published on 10 April 2025

Spain

Comunitat Valenciana

Alzira

About this good practice

Alzira, due to its Mediterranean rainfall pattern and proximity to several ravines, frequently experiences flooding, particularly in the Les Basses area. The existing drainage system is insufficient, causing water accumulation in streets and urban areas, affecting mobility and public safety.
As a proactive adaptation measure, the Alzira City Council built a 920-meter interceptor channel to capture and redirect rainwater flows to the Barranco de la Casella, preventing urban flooding.
Main measures include:
• Proactive rainwater management, collecting and diverting runoff from roads and ravines to a secure discharge point.
• Resilient hydraulic infrastructure, with regulation gates and flow control systems.
• Collaborative decision-making, led by the City Council with hydraulic engineers, urban planners, and local authorities to ensure effective, sustainable solutions.
• Urban integration, minimizing impact on infrastructure and services.
The main beneficiaries are Alzira residents, with fewer floods, and local businesses, facing less rainfall damage.
Local decision-makers also benefit from a proactive strategy that enhances public trust and acceptance of climate resilience measures. Preemptive action strengthens climate risk management, reduces emergency costs, and avoids higher post-disaster recovery expenses.

Expert opinion

The climate crisis is increasing the frequency of flood events, and one in eight Europeans lives in areas prone to river floods. Yet many European regions are not yet adequately prepared for these intensifying extreme weather events. The Alzira interceptor channel is an example of pro-active flood protection and prevention in urban areas. By addressing the causes of flooding through smart water management and infrastructure, Alzira has improved public safety and minimised economic disruption. Other regions, especially flood-prone cities with a similar topography, can learn from its approach. The practice aligns with the EU Floods Directive, which requires member states to take adequate and coordinated action to reduce flood risks.

James Ling

Works at Interreg Europe Policy Learning Platform

Resources needed

• Total budget: Approximately 3 million euros, funded by the General Directorate of Water, ¡ by the City Council for land expropriation and by Aigües de València.
• Human resources: Civil engineers, urban drainage specialists, public works technicians, construction workers, and project managers.

Evidence of success

Since its inauguration in June 2024, the interceptor channel has proven its effectiveness. In October 2024, during an intense storm that brought over 210 liters of rainfall in 24 hours, the usual flooding in areas was minimal, demonstrating the channel’s functionality.
Other key achievements include:
• A critical infrastructure that has prevented significant flooding for the first time in decades.
• Increased drainage capacity and reduced flood risk.

Potential for learning or transfer

This project is replicable in cities facing urban drainage and flood risks, especially those with ravines channeling runoff into urban areas. Its climate-smart approach ensures long-term resilience by integrating risk prevention into urban planning.
• Data-driven planning: Geotechnical studies and hydraulic modeling for effective solutions.
• Proactive decisions: Anticipating risks and taking preventive measures to reduce economic and social impacts.
• Adaptable infrastructure: Applicable in various urban areas with minimal changes.
• Urban integration: Minimizing infrastructure impact and optimizing resources.
• Flow regulation: Gates and safety structures for controlled discharge.
• Mixed funding: Public-private funds ensure viability.
This practice helps flood-prone municipalities improve rainwater management and climate resilience.