Flood Risk in a Heritage City: Alzira as a Case Study

Floods are natural hazards which have damaged cities and their architectural heritage over the centuries. The heritage town of Alzira (Valencia, Spain) is a major case study for the assessment of flood risk in architectural heritage. Alzira was founded by the Al-Andalus Moors on a river island within a bend of the river Jucar, which has overflowed more than 80 times during its history. The main aim of this work is to analyse the vulnerability to floods of the town’s architectural heritage, especially that of earthen architecture, a constructive tradition of which several examples can be found in the town. The proposed methodology attempts to calculate the vulnerability of the earthen architecture through the evaluation and weighting of extrinsic and intrinsic parameters. This makes it possible to identify the constructive characteristics and material weathering which worsen the behaviour of structures during floods. Maximum vulnerability values have been obtained for poorly conserved constructions without cladding. Results highlight the importance of ascertaining suitable strategies for the prevention and mitigation of risk as future lines of research. The vulnerability assessment methodology presented in this study could be applied to other case studies in other sites with architectural heritage under threat from floods.