Natural water retention Toledo

On September 3, 2023, heavy rainfall in central Spain caused flooding in the Toledo and Madrid areas. It is expected that due to climate change, these kinds of rain events will occur more frequently. In collaboration with Wetlands International and Centro Ibérico de Restauración Fluvial, Stroming analyzed what happened on September 3.

Analysis

Four watersheds draining into the Tajo River near Toledo were examined in a quick scan. Using data from local weather stations, precipitation was analyzed, as it largely determines the risk of flooding. Precipitation ranged from 75 mm in the south to 100 mm in the north. The intensity was approximately 40 mm/hour, with locally extreme rainfall (74-134 mm/hour) between 8 and 9 p.m.

Historical maps were also consulted. It was clear that new construction is located in many places in low-lying areas of the landscape. These areas are particularly vulnerable to flooding.

Solutions

A GIS analysis identified where natural solutions are possible. There are ample opportunities in all four watersheds, including greening villages, capturing runoff from asphalt, and developing natural sponge areas in low-lying natural depressions. It is also important not to build further in locations with the highest flooding risks.

The results have been summarized on a digitale website and explained in a report.