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The recent DANA (Isolated Depression at High Altitude) that affected Valencia is a clear example of how the conservation or destruction of riverbanks can influence the impact of these extreme weather events. The intense rains associated with a DANA can cause severe flooding, and in these situations, natural riverbanks with vegetation act as a natural buffer. When these areas are degraded or built over, the risk of flooding and damage increases significantly. When riverbanks are destroyed or built on, the natural spaces that retain and absorb water are reduced, preventing water from infiltrating naturally and causing it to flow into urban areas. In Valencia’s case, the presence of urbanized areas next to rivers and wetlands likely contributed to the flooding, as impermeable surfaces (like asphalt and concrete) prevent water from filtering into the ground, increasing pressure on the drainage system and urban infrastructure.

How Vegetated Riverbanks Could Have Helped

• Rainwater Absorption: Natural riverbanks with vegetation could have helped absorb some of the water, reducing the amount flowing directly into urban areas and thus minimizing flooding.
• Sediment Retention and Erosion Control: With vegetation, riverbank soils would have been more stable, helping retain water and preventing sediment from destabilizing riverbeds. This is especially important in DANA events, where torrential rains can increase erosion of unprotected riverbanks and cause large amounts of sediment to be washed into rivers.
• Natural Water Flow Diversion: Vegetated riverbanks often have natural depressions and other features that help redirect water toward areas with lower flood risk. When these areas are urbanized, however, natural courses are modified, and rainwater is redirected into residential or commercial areas, causing material damage.
• Climate Change Adaptation and Impact Mitigation: In the context of climate change, DANA events are expected to become more frequent and intense. Natural riverbanks with vegetation help mitigate climate change effects by retaining water in wet periods and releasing it in drier periods, maintaining a more regular river flow. Without these spaces, the water cycle becomes unbalanced, worsening the impact of heavy rains.