Flood Risk Assessment of Traditional Adobe Buildings: Analysis of Case Studies in the River Ebro Basin, Spain

Earthen masonry is a historic construction technique widespread in the river Ebro basin (Spain). These masonry walls are made of small earthen blocks, such as adobes [1]. Throughout history frequent floods of the river Ebro have threatened the integrity of earthen masonry construction. Due to climate change, this region is undergoing an increase in the severity and frequency of flood events, causing considerable losses to architectural heritage [2]. According to various studies, earth as a building material has hygroscopic characteristics which influence its resistance to water [3]. The devastating effects of flood events on historic structures due to changes in the interaction between subsoil and foundations include damage to the superstructure [4]. This research proposes a flood risk assessment methodology following a component-based modelling framework. The susceptibility to floods of the building components is evaluated, considering the material, structural and morphological characteristics [5]. The conservation state of the assets is also considered, analysing material weathering, damage, and crack patterns. The individual parameters involved in the assessment have been weighted in order to ensure significant results. The methodology has been applied to a group of municipalities located in the floodplain of the middle course of the river Ebro, and this research aims to carry out a flood risk assessment of adobe buildings on a local scale. Different risk levels have been found depending on the specific characteristics and conservation state of individual assets. The correlation between structural damage and flood effects is examined to identify the origin of damage and recurring crack patterns. Finally, mitigation strategies are discussed in relation to the importance of the conservation of architectural heritage and vernacular construction traditions.