The Ebro depression is configured as a valley of soft materials and low slope surrounded by mountain ranges: the Cantabrian Mountain Range, the Pyrenees and the Iberian System. The precipitation received by these mountain systems converge in the Ebro River, whose course runs along the central axis of the valley. The low gradient of the terrain (in the 325 km that separate the towns of Logroño and La Zaida the slope is 235 m, with a gradient of 0.7 ‰) causes the river to draw large meanders that are abandoned and shaped in episodes of flooding. 

The fertile soils generated in this process have been intensively used for agriculture since historical times. The combination of particularly fertile soils and irrigation water in an arid environment has resulted in the concentration of population and human activity around the river. Technological advances since the second half of the 20th century, especially the hydraulic regulation works on the most important tributaries, have taken the human exploitation of the river, the valley and its resources to previously unknown limits.

However, the middle stretch of the Ebro River has frequent floods that inundate large areas of land due to the valley’s steep slope. These floods have always occurred and there are historical references, but the most notable ones in recent decades and which are still present in the collective memory have been those of 1961, 1966, 1977, 1978, 1978, 1980, 1981, 1993, 2003, 2007, 2015 and most recently that of 2018.

Confluence of the Ebro and Aragón rivers during the flood episode of April 2018.

The protection of properties located in flood zones has consisted, over the last sixty years,  in the construction of structural defense works and in the artificial maintenance of constant drainage sections, cleared of vegetation and sediments. This management model has proven to be unsustainable, as it requires large financial contributions for its recovery after each flood event.

Floods also cause undesirable social impacts, such as the displacement of populations, stress, farm failures, death or slaughter of animals, etc. These impacts on society have generated widespread unrest, leading to widespread calls for long-term solutions.

At the same time, in the last decades the Community regulations have promoted a change of focus in the management of fluvial ecosystems in order to improve and conserve their condition and mitigate risks, under the following European directives:

Following the major floods of 2015, the then Ministry of Agriculture and Fisheries, Food and Environment, the Ebro Hydrographic Confederation and the Autonomous Communities of La Rioja, Aragón and Navarra agreed to implement a plan of measures aimed at increasing the resilience of the system, applying the, at that date recently approved, Flood Risk Management Plan of the Ebro River Basin Demarcation. Thus Ebro Resilience was born.