The effects of climate change in the Mediterranean region have become increasingly evident in recent decades, with extreme episodes of torrential rains, maritime storms, and phenomena like the DANA (High-Level Isolated Depression), which can cause significant material and human loss as well as severe damage to infrastructure. ALSO READ: Over 130,000 march in Valencia to protest handling of deadly floods.
This has, unfortunately, been demonstrated by the rainfall that recently caused catastrophic floods in parts of the Valencia region. Sitges and Sant Pere de Ribes are exposed to these risks, making it essential to develop prevention and response protocols for such phenomena.
A response plan known as the ‘Single Municipal Civil Protection Document’ (DUPROCIM) is a key tool for planning responses to these types of disasters. The main purpose of the document is to provide a detailed guide for actions to be carried out by both local authorities and the general population to reduce the risks associated with extreme weather episodes. However, neither Sitges nor Sant Pere de Ribes currently have their documents it approved, despite being high and very high-risk municipalities, respectively.
In Sitges, the document is awaiting approval because Civil Protection made corrections that require some final adjustments. At the same time, the local council has carried out changes in personnel, and in the last council meeting, the position of Civil Protection coordinator was approved. This is a key role in the event of an emergency, though the method of filling the position (internal promotion or competition) is still being determined.
In Sant Pere de Ribes, the document has been submitted to the Generalitat (Catalan government) and is also awaiting final approval. The Catalan president, Salvador Illa, announced last Tuesday that civil protection plans will be drawn up for all municipalities in Catalonia. Until now, this was not mandatory for all, and there will also be a thorough review of all activities in flood-prone areas.
A DANA is a meteorological phenomenon that occurs when a mass of cold air becomes isolated at high altitudes, surrounded by warmer air. This creates atmospheric instability, which can lead to torrential rains, especially when combined with moisture from the sea. In coastal Mediterranean regions, like Sitges, DANAs can turn into very violent storms, with rainfall exceeding 100mm in just a few hours, causing flash floods. Sitges, due to its location between the sea and the mountains, has a geography that can worsen the consequences of a DANA.
Moreover, the geographical features of the region, with steep slopes that facilitate the rapid movement of water, mean that torrential rains can have a multiplying effect in urbanised areas. The streams that cross the municipalities and flow into the sea can quickly become overwhelmed during heavy rains, resulting in sudden and dangerous surges.
To calculate flood maps, ‘return periods’ are studied. This refers to the probabilities of certain amounts of rainfall occurring in specific areas. A 10-year return period is the most common, representing the usual flow of rivers. A 500-year return period indicates a very high amount of rain, with a very low probability of occurrence. The 100-year return period represents events with a 1% chance of happening; building around such areas is not advisable, though there are often constructions already in place, as is the case in both Sitges and Ribes.
In Sitges, flood zones are concentrated around streams and torrents, as well as in some areas near the coast and other low-lying parts of the town. The area most vulnerable to flooding is the Ribes and Terramar stream. The stream is a critical point for possible overflows during episodes of heavy rainfall, especially in urbanised areas that are nearby, such as the case of Rocamar, which has a specific emergency plan.
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